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Psychometric properties of four anxiety measures in older adults
~
Pergamon
Behav. Res. Ther. Vol. 34, No. 10, pp. 827-838, 1996 Copyright ~c~ 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved S0005-7967(96)00064-2 0005-7967/96 $15.00 + 0.00
PSYCHOMETRIC PROPERTIES OF FOUR ANXIETY MEASURES IN OLDER ADULTS MELINDA A. STANLEY *~, J. GAYLE BECK2 and BARBARA J. ZEBB2 ~University of Texas Health Science Center, 1300 Moursund Avenue, Houston, TX 77030-3497, U.S.A. and :State University of New York, Buffalo, NY 14260, U.S.A. (Received 7 May 1996)
Summary--Despite relatively high prevalence rates of anxiety disorders in older adults, little attention has been paid to the establishment of psychometrically sound measures for this population. The current study addresses this issue by examining the psychometric properties of four self-report anxiety measures: the Spielberger State-Trait Anxiety Inventory (STAI), Worry Scale (WS), Fear Questionnaire (FQ), and Padua Inventory (PI). Two older adult community subsamples were assessed, one with Generalized Anxiety Disorder (GAD; n = 50) and the other with no anxiety complaints (Normal Controls: NC; n = 94). Descriptive data revealed that mean scores in the GAD sample were similar to those reported in studies of younger GAD patients. Mean scores in the NC sample, however, were lower than those reported in studies of younger control samples. Internal consistency for all measures generally was adequate in both the GAD and NC subsamples, although alpha coefficients for two of the FQ subscales were marginal. Test-retest reliability over a 2~, week interval (assessed in a subgroup of NC subjects) was mixed, with some measures apparently assessing stable, trait-like dimensions of fear and anxiety, and others estimating more state-like clinical features. Intercorrelations among subscales for all four measures in both the GAD and NC groups generally were high and consistent with findings from prior research. Finally, some support for the convergent validity of the four anxiety measures was obtained, particularly in the NC sample. Results are discussed in terms of the utility of these instruments for future investigations of the psychopathology and treatment of anxiety disorders in the elderly. Copyright © 1996 Elsevier Science Ltd
INTRODUCTION Anxiety disorders pose a significant public health problem for older adults, with 1- and 6-month prevalence rates of 4.6% and 6.8%, respectively (Regier et al., 1988; Weissman et al., 1985). Despite these relatively high figures, empirical data addressing the nature and treatment of anxiety in the elderly have only begun to emerge. Of central importance to future investigations in this domain is the establishment of psychometrically sound anxiety measures for older adults. Unfortunately, little attention has been paid to this issue, and the few existing studies are limited by diagnostically heterogeneous samples and the omission of semistructured interview procedures to classify Ss (Hersen & Van Hasselt, 1992). In younger adults, a wide range of instruments has been established to measure anxiety symptoms in samples with and without anxiety disorders [e.g. Fear Survey Schedule (FSS: Geer, 1965); State-Trait Anxiety Inventory (STAI: Spielberger, Gorsuch & Lushene, 1970)]. As such, initial steps toward the development of comparable assessment strategies for older adults might involve examination of the psychometric properties of these same instruments. Early investigations in this domain evaluated the utility of the STAI in samples of community-dwelling older adults and elderly psychiatric inpatients and outpatients (Himmelfarb & Murreil, 1983; Patterson, Sullivan & Whitbourne, 1980). Although these studies demonstrated some support for the reliability and validity of the STAI, conclusions were limited by the use of diagnostically heterogeneous clinical samples and the omission of structured interview assessments (Hersen & Van Hasselt, 1992). In addition, available data have not yet addressed the psychometric properties of other commonly-used anxiety measures in samples of older adults. An alternative psychometric assessment strategy involves the development of new instruments specifically targeting anxiety symptoms in the elderly. For example, Wisocki and colleagues *Author for correspondence. 827
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Melinda A. Stanleyet al.
developed the Worry Scale (WS: Wisocki, Handen & Morse, 1986), a 35-item self-report measure that assesses financial, health, and social worries commonly associated with aging. Preliminary reports provided mean scores and some support for the concurrent validity of the WS in community-dwelling and homebound older adults based on given significant correlations with other self-report measures of anxiety (Wisocki et al., 1986; Wisocki, 1988). An additional study compared WS scores in older and younger samples (Powers, Wisocki & Whitbourne, 1992). However, internal consistency and test-retest reliability have not been examined, and the samples used in these reports were community residents. Thus, the applicability of the WS for well-diagnosed clinical and nonclinical samples is unknown. To set the stage for future investigations of psychopathology and treatment in anxious older adults, it is necessary to examine the psychometric properties of a variety of available instruments in well-diagnosed clinical and community samples of older adults (Hersen & Van Hasselt, 1992; Sheikh, 1991). In an initial investigation in this regard, the reliability and validity of the Penn State Worry Questionnaire (PSWQ: Meyer, Miller, Metzger & Borkovec, 1990) were examined in 47 older adults with Generalized Anxiety Disorder (GAD) and 94 normal control (NC) Ss, ages 55-82 (Beck, Stanley & Zebb, 1995). All Ss were classified using the Anxiety Disorders Interview Schedule--Revised (ADIS-R: DiNardo & Barlow, 1988), a semistructured interview designed to assist in the diagnosis of anxiety and affective disorders. Results revealed adequate internal consistency (coefficient ~ > 0.80) and convergent validity, as documented by significant correlations with related self-report measures of anxiety, for the PSWQ in both GAD and NC groups. Similar investigations are needed to examine other commonly-used self-report anxiety measures in older patient and control samples. In this regard, further examination of measures that target clinical features of individuals with GAD would be particularly useful. Recent epidemiological data have suggested that GAD is one of the most prevalent of the anxiety disorders in older adults, with 6-month and lifetime rates of 1.9% and 4.6% (Blazer, George & Hughes, 1991). Given these figures, along with the pervasiveness and chronicity of GAD (Rapee & Barlow, 1991), further investigation of the nature and treatment of generalized anxiety and associated symptoms in the elderly is warranted. Prior to such investigations, well-validated measures of relevant clinical features will need to be established. These measures should address the severity of worry, a core feature of GAD (American Psychiatric Association, 1987, 1994), as well as general feelings of anxiety. As noted above, prior data have addressed the psychometric properties of the PSWQ, an established self-report measure of worry, in well-diagnosed samples of older adults. However, further examination of the WS, a measure targeting worries commonly associated with aging, and the STAI, a well-established measure of general anxiety, are still needed. Specifically, examination of reliability and validity of these instruments is needed in well-diagnosed GAD and normal samples of older adults. In addition, given the proposed overlap between worry and obsessionality (Freeston, Ladouceur, Rheaume, Letarte, Gagnon & Thibodeau, 1994; Turner, Beidel & Stanley, 1992), as well as the high prevalence of coexistent social and simple phobias in GAD (Sanderson & Wetzler, 1991), measures to assess severity of obsessions and related fears also need to be established. In this regard, psychometric evaluation of the Padua Inventory (PI: Sanavio, 1988), a questionnaire evaluating the severity of obsessions and compulsions, and the Fear Questionnaire (FQ: Marks & Mathews, 1979), a measure of avoidance related to social, agoraphobic, and blood injury fears, would be useful. As such, the present study evaluated the psychometric properties of four self-report instruments: WS, STAI, PI and FQ. Participants included two groups of community-dwelling older adults, one without anxiety complaints and one with GAD, both classified according to the ADIS-R.
METHOD Participants Generalized anxiety disorder (GAD) subsample. Demographic information on the samples is shown in Table 1. The GAD subsample included 50 older adults, ages 55-81, who met DSM-III-R criteria for GAD (American Psychiatric Association, 1987). Age distribution of the sample was as follows: 55-59 (16%); 60-64 (12%); 65 and older (72%). Prospective participants were recruited
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Table 1. Demographic data for older adults with generalized anxiety disorder (GAD) and a subsample of normal controls (NC)
Age: Mean (SD) Education: Mean (SD) Gender Female Ethnicity Caucasian African-American Hispanic Native American Marital Status Married Divorced Widowed Single
G A D subsample (n = 50)
NC subsample (n = 94)
67.92 yr (6.81) 14.46 yr (2.79)
67.53 yr (6.77) 15.20 yr (2.24)
72.0% (n = 36)
69.1% (n = 65)
82.0% 14.0% 2.0% 2.0%
(n (n (n (n
= = = =
41) 7) 1) 1)
95.7% (n = 90) 2.1% (n = 2) 2.1% (n = 2) 0
66.0% 16.0% 14.0% 4.0%
(n (n (n (n
= = = =
33) 8) 7) 2)
62.8% 17.0% 17.0% 3.2%
(n (n (n (n
= = = =
59) 16) 16) 3)
with media announcements, as well as visits to community agencies and church groups for older adults, and were screened initially by telephone. Those individuals whose symptoms appeared to fit GAD criteria were then interviewed using the ADIS-R by advanced-level graduate students who received extensive training in the administration of this instrument (DiNardo, Moras, Barlow, Rapee & Brown, 1993). Participants who reported current use of psychotropic medication, with the exception of occasional hypnotics for sleep difficulties (i.e. less than four times per week), were asked to withdraw from these regimes under supervision of the prescribing physician, with at least a 2-week clearance prior to administration of the ADIS-R. Exclusion criteria included: primary diagnosis of an alternate Axis I disorder, current involvement in psychotherapy, serious medical conditions (e.g. recent stroke, acute cardiac disease, or Parkinson's disease), alcohol or substance abuse within the previous 6 months, psychotic symptoms, or evidence of cognitive impairment according to a score of 24 or lower on the Mini-Mental State examination (Folstein, Folstein & McHugh, 1975)*. All ADIS-R interviews were videotaped, with a random 28% (n = 14) selected for evaluation by a second clinician to estimate interrater agreement. One-hundred per cent diagnostic agreement was noted for GAD, most likely due to extensive prescreening of potential participants and the use of videotaped interviews rather than administration of two separate ADIS-Rs (Borkovec & Costello, 1993). Secondary diagnoses were as follows: Social Phobia 16% (n = 8), Simple Phobia 12% (n = 6), Major Depression 12% (n = 6), Panic Disorder 10% (n = 5), Dysthymia 4% (n = 2), and Post Traumatic Stress Disorder 2% (n = 1). Kappa coefficients for secondary diagnoses indicated excellent reliability (1.00) for Social Phobia, Simple Phobia, and Panic Disorder, and moderate reliability (0.58) for Major Depression. Other diagnoses did not occur with sufficient frequency in the reliability sample to allow calculation of kappa coefficients. Normal control (NC) subsample. The NC subsample included 94 adults, ages 55-82, without any DSM-III-R Axis I diagnosis. Age distribution mirrored that of the GAD group, with frequencies as follows: 55-59 (16%); 60-64 (12%); 65 and older (72%). These individuals were recruited in the same fashion as the GAD subsample, and initial telephone screenings were followed by administration of the ADIS-R to confirm the absence of any Axis I disorder. Other exclusion criteria for this group were similar to those noted for the GAD group. Measures
All GAD and NC participants completed the Spielberger State-Trait Anxiety Inventory (STAI; Spielberger et al., 1970), the Worry Scale (WS; Wisocki et al., 1986), the Padua Inventory (PI; Sanavio, 1988), and the Fear Questionnaire (FQ; Marks & Mathews, 1979). The STAI is a well-known 40-item instrument which includes both state and trait scales, measuring respectively transient and enduring levels of anxiety. Strong psychometric support is available for the STAI with younger adults (Spielberger et al., 1970), and preliminary data from *A c u t - o f f s c o r e o f 17 w a s used f o r i n d i v i d u a l s w i t h a n e i g h t h g r a d e o r less e d u c a t i o n ( M u r d e n , M c R a e , K a n e r & B u c k n a m , 1991).
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heterogeneous community and psychiatric samples of older adults suggest adequate internal consistency and convergent validity (Himmelfarb & Murrell, 1983; Patterson et al., 1980). The WS is a 35-item questionnaire developed to assess severity of financial, health, and social worries in older adults (Wisocki et al., 1986). As noted above, although mean scores from community dwelling and homebound elderly are available (Powers et al., 1992; Wisocki et al., 1986; Wisocki, 1988), few psychometric data have been reported. The FQ is a 15-item inventory assessing severity of avoidance related to agoraphobic, social, and blood-injury fears. Psychometric data for this instrument in younger adults with and without anxiety are adequate (Marks & Mathews, 1979; Trull & Hillerbrand, 1990; Oei, Moylan & Evans, 1991), but the FQ has not been used with older adults. The PI is a 60-item questionnaire designed to evaluate obsessive-compulsive symptoms. Four subscales assess severity of contamination and checking rituals, as well as fears of losing control over mental activities and motor behaviors. Psychometric support for this instrument in younger patient and control samples is good (Sternberger & Burns, 1990; Van Oppen, 1992). The PI has not been used previously with older adults.
Procedure Following evaluation of inclusion/exclusion criteria, participants in the G A D subsample completed the measures described above as part of a broader pretreatment evaluation.* NC participants completed these same instruments in the context of a briefer evaluation and were paid $50 for their participation. All participants provided informed consent, and demographic data for both groups are presented in Table 1. For a subset of NC participants (n = 46), questionnaires were readministered 2~4 weeks later ( X = 19.0 days, SD = 7.1) to allow evaluation of test-retest reliability. Although this test retest interval was somewhat variable due to scheduling difficulties, the majority of participants (76%) were re-evaluated within 3 weeks of the initial testing. RESULTS
Data analytic strategies All psychometric analyses for the STAI, WS, PI and FQ were conducted separately for the G A D and NC samples.? Within each group, gender differences for each anxiety measure were examined, and mean scores were compared to those from similar samples of younger adults using z-score comparisons of means. Internal consistency for each measure was then estimated with coefficient alpha, calculated separately for subscale and total scores of each instrument. Also within each sample, the interrelationships of subscale scores for each measure were examined with Pearson r correlation coefficients and statistical comparisons of dependent rs (Cohen & Cohen, 1983). Convergent validity was examined with Pearson r correlation coefficients assessing the interrelationships of scores on the four measures. In an attempt to control for experimentwise error rate, the nominal alpha for these correlations was set to 0.01. For the subset of NC Ss to whom the questionnaires were administered a second time, test-retest reliability was estimated with Pearson r correlation coefficients. Again, correlations were calculated separately for subscale and total scores of each measure.
G A D subsample Descriptive data. Means and standard deviations for the STAI, WS, FQ and PI in the G A D subsample are included in Table 2. No significant gender differences were noted on any measure, *It should be noted that questionnaire data were unavailable for 2 of the 50 Ss in the GAD group. tStatistical comparisons of scores between the GAD and NC subsamples will not be addressed here given some overlap with a separate report intended to document the psychopathologicalfeatures of GAD in older adults relative to a matched sample of NC participants (Beck, Stanley & Zebb, 1996). In that study, matched subgroups of the samples included here were compared with regard to various clinical features (e.g. anxiety, depression, associated fears) to provide a description of the nature of GAD and coexistent symptomatologyin older adults. It should be noted that the primary foci of these two studies are different. Additionally, the NC subsample described here is twice as large as the matched group, and the psychopathologywork utilized a broader range of measures than those described here. However, to avoid the presentation of any potentially redundant data in the two reports, direct comparison of scores in the GAD and NC subsamples were omitted here.
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Table 2. Mean scores, standard deviations, and coefficient alphas for four measures of anxiety in older adults with generalized anxiety disorder (GAD subsample; n = 50) Measure STAI A-State (20 items) A-Trait (20 items) WS Social (13 items) Finances (5 items) Health (17 items) Total (35 items) FQ Blood-Injury (5 items) Agoraphobia (5 items) Social Phobia (5 items) Total (15 items) PI Mental Control (17 items) Contamination (11 items) Checking (8 items) Behavior Control (7 items) Total (60 items)
Mean (SD)
Possible range
:t
45.0 (13.1) 48.0 (I 1.9)
20-80 20-80
0.94 0.88
13.2 4.1 18.3 35.4
(9.5) (3.6) (10.5) (20.9)
0-52 0-20 0-68 0-140
0.91 0.76 0.86 0.93
9.7 6.8 9.9 26.1
(6.3) (5.5) (6.2t (14,5)
0-40 0-40 0~.0 0--120
0.73 0.61 0.67 0.82
12.8 8.0 5.7 0.9 31.0
(11.4) (6.71 (5.5) (1.8) (21.8)
0-68 0-44 0-32 0-28 0-240
0.90 087 0.85 0.74 0.95
STAI = State-Trait Anxiety Inventory; WS = Worry Scale; FQ = Fear Questionnaire; PI = Padua Inventory.
Note:
so means were collapsed across this variable. Scores on the STAI-Trait subscale and FQ-Total scale in the older adult GAD group were similar to those reported in studies of younger adults with GAD [ Barlow, Rapee & Brown, 1992 (mean age = 40.6 yr); STAI-Trait: z = 1.32, NS; FQ: z = 0.68, NS]. Scores on the WS in the GAD subsample, however, were significantly higher than those reported in community samples of elders [ Powers et al., 1992 (mean age = 77.6 yr); Wisocki, 1988 (mean age = 72.0 yr); z = 2.42-3.31, P < 0.05]. Internal consistency. Alpha coefficients (see also Table 2) indicated adequate to strong internal consistency for all subscale and total scores of the STAI, WS, and PI (Nunnally & Bernstein, 1994; Robinson, Shaver & Wrightman, 1991). Internal consistency for the FQ Blood-Injury and Total scores also were adequate, although coefficients for the Agoraphobia and Social Phobia subscales were marginal. Examination of item-remainder correlations revealed a range of 0.31-0.48 for the Agoraphobia subscale and 0.29-0.60 for the Social Phobia subscale. In neither case did the deletion of any one item improve internal consistency. Interrelationships ofsubscales. Intercorrelations of subscale scores for the anxiety measures in the GAD subsample are presented in Table 3. As noted in prior reports with both older and younger samples (e.g. Endler, Cox, Parker & Bagby, 1992; Patterson et al., 1980; Tanaka-Matsumi & Kameoka, 1986), the STAI State and Trait subscales correlated significantly. In addition, all WS subscale scores correlated significantly with each other and with the Total score. However, the Finances subscale was less strongly related to Total WS scores than were the Social or Health subscales (correlation of dependent rs; P < 0.025), a finding that is consistent with prior research (Powers et al., 1992). The weaker relationship between financial worries and total WS scores may result from the relatively small number of items that comprise the Finances subscale (see Table 2). Intercorrelations for the FQ revealed that the Agoraphobia subscale correlated significantly with both the Blood-Injury and Social Phobia subscales, although the latter two measures were unrelated (see Table 3). However, each of the FQ subscales correlated similarly with Total FQ scores (comparisons of dependent rs; all Ps > 0.10). Finally, significant relationships were noted between the PI-Mental Control, Contamination, and Checking subscales (see Table 3). The Behavior Control subscale also correlated significantly, but less strongly, with the Mental Control and Checking subscales, but was unrelated to the Contamination subscale. This pattern is congruent with prior research in younger samples (Van Oppen, 1992). Finally, all PI subscale scores correlated similarly with the Total score (comparisons of dependent rs; all Ps > 0.10). Convergent validity. Intercorrelations of the anxiety measures in the GAD subsample are presented in Table 4. Significant positive correlations were obtained between the STAI-Trait, WS, and PI, demonstrating adequate convergent validity among measures of trait anxiety, worries, and
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Table 3. lntercorrelations of subscale scores for the STAI, WS, FQ, and PI in the G A D subsample (n = 50) STAl-State STAI-Trait WS Social Finances Health FQ Blood-Injury Agoraphobia Social Phobia PI Mental Control Contamination Checking Behavior Control
0.74** Finances 0.58**
Health 0.75** 0.46**
Agoraphobia 0.59**
Social Phobia 0.27 0,49**
Contamination 0.55*
Checking 0.80** 0.60**
Total 0.93** 0.67** 0.92** Total 0.77** 0,84** 0.74** Behavior Control 0.42* -0.03 0.40*
Total 0.70** 0.56** 0.58** 0.57**
*P < 0.01; **P < 0,001. Table 4. Intercorrelations of anxiety measures in the G A D subsample (n = 50) WS-Total STAI State Trait WS-Total PI-Total
0.22 0.40*
PI-Total
FQ°Total
0.21 0.44* 0.46**
0.16 0.34 0.24 0.12
*P < 0.01; **P < 0,001
obsessive-compulsive symptoms in older adults with GAD (Seibel, 1968). The STAI-State and FQ scales, however, failed to correlate significantly with other measures of anxiety.
NC subsample Descriptive data. Means and standard deviations for the STAI, WS, FQ, and PI in the NC subsample are reported in Table 5. Again, no significant gender differences emerged on any of these measures. Table 5 also includes representative mean scores from other literature with younger adult control samples. Comparison of means in the two groups revealed significant differences on all measures, with older adults scoring consistently lower than younger samples (see z-scores, Table 5). Internal consistency. Coefficient alphas (Table 6) indicated adequate to strong internal consistency for subscale and total scores in the NC subsample (Nunnally & Bernstein, 1994; Robinson et al., 1991), with the exception of the FQ-Social Phobia and PI-Behavior Control subscales. For the FQ-Social Phobia subscale, item-remainder correlations ranged from 0.25 to Table 5. Mean scores on four measures of anxiety in older adults without psychiatric diagnoses (NC subsample; n = 94) and younger adult normal controls Measure STAI State Trait WS Social Finances Health Total FQ Blood-Injury Agoraphobia Social Phobia Total PI Mental Control Contamination Checking Behavior Control Total
Older adults
Younger adults'
z-score comparison of means b
26.5 (6.8) 26.8 (5.7)
35,8 (9.5) 37.9 (9.4)
11.34 15.42
4.0 1.1 6.0 11.0
(4.3) (1.7) (5,8) (10.4)
13.3 5.4 14.0 32.6
(8.0) (3.6) (8.2) (17.7)
9.03 9.55 7.08 9.31
5.2 3.6 4.9 13.6
(5.2) (4.3) (3.7) (10.9)
8.1 4.9 8.8 24,9
(6.2) (5.6) (5.8) (16.0)
4.03 2.10 6.61 6.81
3.0 4.0 2.2 0.2 12.4
(3.7) (4.6) (3.0) (0.6) (12.3)
----41.3 (25.8)
18.06
'Younger adult scores taken as follows: (1) STAI (Spielberger et al., 1970; 484 college undergraduates); (2) WS (Powers et al., 1992, 74 college undergraduates, mean age = 20.4 yr); (3) FQ (Mizes & Crawford, 1986; 172 adults, mean age ffi 41.5 yr); (4) PI (Sternberger & Burns, 1990; 701 college undergraduates, mean age = 18.9 yr). bAll :-scores significant at P < 0.05.
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Table 6. Coefficient alphas and test-retest (2-4 weeks) correlation coefficients for four measures of anxiety in the NC subsample Measure
Coefficient x (n = 94)
Test-retest coefficient (n = 46)
0.85 0.79
0.62 0.84
0,88 0.80 0.91 0.94
0.76 0.80 0.58 0.69
0.79 0.74 0.60 0.85
0,57 0.41 0.64 0.52
0.79 0.86 0.85 0.19 0.91
0.61 0.79 0.64 0.75 0.80
STAI State (20 items) Trait (20 items) WS Social (13 items) Finances (5 items) Health (17 items) Total (35 items)
FQ
Blood-lnjury (5 items) Agoraphobia (5 items) Social Phobia (5 items) Total 115 items) PI Mental Control (17 items) Contamination (11 items) Checking (8 items) Behavior Control (7 items) Total (60 items)
0.54, and no significant improvement in internal consistency occurred following deletion of any single item. Item-remainder correlations for the PI-Behavior Control subscale ranged from - 0.05 to 0.27. Deletion of item 57 ("I feel I have to make special gestures or walk in a certain way") increased coefficient alpha (from 0.19 to 0.36), although inadequate internal consistency was still noted. Examination of frequency distributions for items on the PI-Behavior Control subscale also revealed that over 90% of NC participants scored zero on each, suggesting that restricted range may have contributed to poor internal consistency of this subscale.
Test-retest reliability. Correlation coefficients (Table 6) indicated strong test-retest reliability for the STAI-Trait and a weaker relationship over time for scores on the STAI-State, as might be expected, although statistical comparison of these correlations revealed no significant difference (z = 1.00, NS). Test-retest reliability for the WS generally was adequate, with the exception of the Health subscale. On this subscale, however, post hoc paired comparisons revealed no significant differences in scores at times 1 and 2, suggesting no consistent pattern of change in health-related worries over time. In general, subscale and total scores on the FQ were not stable over time. Post hoc comparisons of means on this measure revealed significantly lower scores at time 2 than time 1 for Agoraphobia, Social, and Total scores, suggesting a consistent pattern of change over time. Test-retest reliability for the PI was somewhat inconsistent, with adequate coefficients demonstrated for Contamination, Behavior Control, and Total scores, but only marginal stability for subscales measuring Mental Control and Checking. Post hoc paired comparisons of these measures revealed no consistent pattern of change from time 1 to time 2. Interrelationships of subscales. Intercorrelations of subscale scores for the STAI, WS, FQ, and PI in the NC subsample are presented in Table 7. As in the GAD subsample, STAI-State and Trait subscales were significantly correlated. All WS subscale scores also correlated significantly with Table 7. Intercorrelations of subscale scores for the STAI, WS, FQ and PI in the NC subsample (n = 94) STAI-Trait WS Social Finances Health FQ Blood-Injury Agoraphobia Social Phobia PI Mental Control Contamination Checking Behavior Control *P < 0.01; **P < 0.001.
STAI-State 0.74** Finances 0.44**
Health 0.80** 0.42**
Agoraphobia 0.50**
Social Phobia 0.47** 0.65**
Contamination 0.45**
Checking 0.57** 0.64**
Total 0.92** 0.58** 0.95** Total 0.83** 0.85** 0.82** Behavior Control 0.49** 0.19 0.26
Total 0.84** 0.77** 0.83** 0.48**
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Table 8. Intercorrelations of anxiety measures in the NC subsample (n = 94)
STAI State Trait WS-Total PI-Total
WS-Total
P1-Total
FQ-Tota!
0.41"* 0.57**
0.48** 0.57** 0.50**
0.38** 0.43** 0.34** 0.62**
**P < 0.001.
each other and with the Total score, although the Finances subscale again was less strongly related to the Total than were the Social or Health subscales (comparison of dependent rs; P < 0.005). Intercorrelations for the FQ revealed that all subscales correlated significantly with each other, and each related similarly to the Total FQ score (comparisons of dependent rs; all P > 0.10). Finally, significant relationships were noted between the PI Mental Control, Contamination, and Checking subscales (Table 7). The Behavior Control subscale, however, correlated only with the Mental Control subscale; it was unrelated to the Contamination and Checking subscales. Further, the Behavior Control subscale correlated less strongly with the Total PI score than the other three subscales (comparison of dependent rs; P < 0.025). Convergent validity. Intercorrelations among the anxiety measures in the NC subsample are presented in Table 8. Significant correlations were observed among all measures of anxiety, demonstrating adequate convergent validity between measures of state and trait anxiety, worries, obsessive-compulsive symptoms, and specific fears (Seibel, 1968). DISCUSSION The goal of the present study was to investigate the psychometric properties of four measures of anxiety (STAI, WS, FQ, PI) in older adults with and without anxiety complaints. All Ss were selected for participation according to the ADIS-R, and psychometric analyses addressed descriptive data, internal consistency, test-retest reliability, interrelationships of subscales, and convergent validity. Examination of descriptive data indicated no gender differences on any of the four measures in either the GAD or NC subsamples. Although gender differences on some of these measures have been reported for younger adult samples (e.g. Mizes & Crawford, 1986; Sanavio, 1988), the current study suggests that gender differences on measures of anxiety may not be significant in older anxious and non-anxious adults. When possible, mean scores in the older adult GAD group were compared with those from younger GAD samples. Results revealed no significant differences, suggesting some degree of overlap in the symptom pictures of younger and older GAD patients. These results must be interpreted cautiously, however, given that equivalent mean scores do not necessarily indicate similar patterns of symptoms. It is possible that older adults are more likely to report certain types of symptoms (e.g. somatic) than younger samples. Age-related differential symptom patterns, in fact, have been reported in the depression literature. In particular, older adults are less likely to endorse symptoms of dysphoria or anhedonia and more likely to acknowledge sleep impairment, thoughts of death, and passive suicidal ideation than younger adults even at similar levels of depression (Gallo, Anthony & Muthen, 1994). Comparisons between the older adult NC group and younger normal control samples revealed consistently lower scores in the elderly. The meaning of this finding is unclear, however, given that older adult NC participants were selected via diagnostic interviews to be free of any psychiatric disorder, unlike selection procedures for younger adult control samples. It is possible, therefore, that differences reported here are the result of heterogeneous younger adult 'normal' groups wherein some proportion of participants met criteria for psychiatric disorders. Differences in educational, social, and other demographic data also could account for the apparent divergence in symptoms reported by older and younger samples. On the other hand, the notion that normal samples of older adults report fewer anxiety complaints than younger control samples cannot be disregarded. In fact, epidemiological data have shown lower rates of anxiety disorders in older adults relative to younger samples (Regier et al., 1988). In addition, Wisocki et al. (1986) reported relatively few worries overall in a sample of community-dwelling normal adults, and Powers et al.
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(1992) documented significantly fewer worries in a similar sample relative to a group of college undergraduates. Although it is possible that non-anxious elderly individuals genuinely worry less than younger adults, the tendency of older adults to under-report worries also should be considered (Oxman, Barrett, Barrett & Gerber, 1987). Examination of internal consistency revealed adequate alpha coefficients for subscale and total scores for the STAI, WS, and PI in both groups, with the exception of the PI-Behavior Control subscale in the NC subsample wherein the small number of items (n = 7) and restricted range of scores may have contributed to subscale instability. As such, the data suggest that these measures generally assessed the constructs of worry, state and trait anxiety, and obsessive-compulsive complaints in a reliable fashion for older adults with and without GAD. In addition, estimates of internal consistency for the FQ Total and Bodily Injury subscales revealed adequate reliability in both GAD and NC older adults. Alpha coefficients for the FQ Social Phobia subscale in both groups, however, and the FQ Agoraphobia subscale in the GAD group were marginal. It should be noted that estimates of internal consistency for the FQ subscales in younger adult anxious and non-anxious samples also have not been consistently high (Cox, Swinson & Shaw, 1991; Trull & Hillerbrand, 1990), suggesting that these subscales may not provide consistently reliable evaluations of specific phobias in any age group. The small number of items comprising each subscale (n = 5) may contribute to these marginal coefficients in both younger and older samples. Nonetheless, further investigations of this measure in older adults with different anxiety disorders, particularly those characterized by specific fears or phobias (Liddell, Locker & Burman, 1991), would be useful. Coefficients of test-retest reliability (assessed in a subsample of NC Ss) were mixed, with some measures apparently assessing stable, trait-like dimensions of fear and anxiety, and others estimating more state-like clinical features. Of particular interest in this regard, worries about financial and social concerns remained consistent over the 2-4 week retest interval, but health-related worries were unstable over time. It is possible that the WS Health subscale assessed sensitivity to real physical complaints which varied over time for non-anxious older adults, whereas financial and social issues remained more stable for individuals in this group. The failure of post hoc comparisons to document a significant difference in WS Health scores over time is consistent with this hypothesis. All FQ scores also indicated poor stability over time, suggesting that this measure of social, agoraphobic, and bodily-injury fears may have varied in a state-like fashion for older adults without anxiety complaints. Post hoc comparisons, however, revealed a consistent pattern of decreasing fear over time, indicating the possibility of regression on this measure. These data highlight the need for further investigations into the measurement of specific fears for older adults. Although test-retest reliability for all anxiety measures has yet to be investigated in older adults with GAD, data from NCs suggest the potential need for development of alternative measures of specific fears for the elderly since the FQ may be unreliable in this population. The impact of a somewhat variable test-retest interval on estimates of stability for all instruments also must be considered. Intercorrelations among subscales for all anxiety measures in both the GAD and NC groups generally were high and consistent with findings from prior research (e.g. Endler et al., 1992; Patterson et al., 1980; Van Oppen, 1992). However, the severity of financial worries was less strongly correlated with WS Total scores than other WS subscales in both GAD and NC groups, possibly due to the smaller number of items comprising the Finances subscale. It also is possible, however, that financial concerns in the elderly are somewhat independent of other worries. In both participant groups, fears of losing control over motor behaviors also were somewhat independent from other dimensions of obsessive-compulsive symptomatology measured by the PI (e.g. contamination fears, fears of loss of control over mental function, and checking behaviors). Although this finding is similar to that reported in younger adults (Van Oppen, 1992), the relative independence of fears related to loss of motor control in the subsamples assessed here may probe real-life concerns about loss of motor function in advanced age. However, the restricted range of scores on this subscale also may explain the lack of relationship with other measures of obsessive-compulsive complaints. Participants in this study (both GAD and NC) reported very few concerns about loss of control over motor behaviors. Some support for the convergent validity of the four anxiety measures was obtained, particularly in the NC subsample. In that group, all correlations among the four measures of anxiety were BRT 34']0--F
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Melinda A. Stanleyet al.
statistically significant, suggesting some degree of relatedness among measures of various anxiety symptoms in non-anxious older adults. In the GAD group, significant correlations were obtained among the WS, STAI-Trait, and PI, indicating convergence among measures of worry, trait anxiety, and obsessionality. Overlap in these clinical features has been noted in prior literature (e.g. Freeston et al., 1994; Turner et al., 1992). The STAI-State and FQ, however, failed to correlate significantly with other measures of anxiety, suggesting that for older adults with GAD, state anxiety and specific fears or phobias may be unrelated to severity of worry, trait anxiety, and obsessive-compulsive symptoms. It is also possible, however, that lower reliability coefficients for these measures may account for the failure to document convergent validity. Lack of convergence in these cases may result from the fact that some aspects of anxiety associated with GAD represent stable, trait-like features, whereas others appear to be more state-like clinical characteristics, as noted earlier. It also should be noted that conclusions regarding convergent validity in general are limited by the omission of measures that would allow examination of divergent validity (e.g. measures of depression). In summary, empirical support for the psychometric properties of the WS, STAI, and PI was obtained in well-diagnosed older adults with and without anxiety complaints. These measures, along with the PSWQ (Beck et al., 1995), should be useful for future investigations of psychopathology and treatment in older anxious adults. Additional data are needed, however, to address discriminant validity, i.e. the utility of these measures for differentiating older adults with G A D from those with other anxiety disorders (e.g. panic disorder, specific phobias), alternate psychiatric syndromes (e.g. depression), or serious medical conditions. Likewise, content validity of the STAI and PI will need to be examined given that these measures were developed for younger samples. As noted by Kasniak (1990), age-related differences in symptom experience may threaten content validity in this regard. This issue is less of a concern for the WS since it was developed to assess worries specific to the experience of older adults. Sensitivity to treatment effects for these measures also has yet to be documented. Reliability data for the FQ suggest that additional consideration should be given to the measurement of specific fears in the elderly. Examination of test-retest reliability in the GAD subsample was omitted here and should be investigated in future research. More broadly, an investigation of psychometric properties of the FQ is needed in samples of older adults whose symptoms meet criteria for various types of phobias. In this regard, issues of content validity will be of particular importance. The utility of other measures of specific fears also should be considered, with particular attention to instruments which utilize a larger number of items to assess related symptoms commonly reported by the elderly. The potential need for development of a new measure that targets fears specific to the elderly also should be considered. Limitations of the present work include the failure to examine test-retest reliability of measures in the GAD subsample, omission of data to address discriminant validity, and the use of small sample sizes that precluded examination of factor structures. In addition, generalizability of the work is limited given that the majority of participants in both groups were well-educated, community-dwelling, Caucasian adults. Future studies will need to address the utility of these measures in samples of more ethnically and socioeconomically diverse elders. Acknowledgements--This researchwas supported in part by a grant from the Texas Higher EducationCoordinatingBoard
(003652-075) awarded to the first and second authors. The authors would like to thank Drs David Lachar, Diane Novy, and John Overall, as well as four anonymousreviewers, who provided commentson earlier versions of this work.
REFERENCES American PsychiatricAssociation(1987). Diagnostic and statistical manual of mental disorders (3rd ed., rev.). Washington, DC: Author. American PsychiatricAssociation(1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington,DC: Author. Barlow, D. H., Rapee, R. M., & Brown, T. A. (1992). Behavioral treatment of generalized anxiety disorder. Behavior Therapy, 23, 551-570. Beck, J. G., Stanley,M. A., & Zebb, B. J. (1995). Psychometricproperties of the Penn State Worry Questionnairein older adults. Journal of Clinical Geropsychology, 1, 33-42.
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Beck, J. G., Stanley, M. A., & Zebb, B. J. (1996). Characteristics of generalized anxiety disorder in older adults: A descriptive study. Behaviour Research and Therapy, 34, 225-234. Blazer, D., George, L. K., & Hughes, D. (1991). The epidemiology of anxiety disorders: An age comparison. In C. Salzman. & B. D. Lebowitz (Eds.), Anxiety in the elderly (pp. 17-28). New York: Spring Publishing Company. Borkovec, T. D., & Costello, E. (1993). Efficacy of applied relaxation and cognitive-behavioral therapy in the treatment of generalized anxiety disorder. Journal of Consulting and Clinical Psychology, 61, 611-619. Cohen, J., & Cohen, P. (1983). Applied multiple regression/correlation analysis for the behavioral sciences (2nd ed.). Hillsdale, N J: Lawrence Erlbaum Associates. Cox, B. J., Swinson, R. P., & Shaw, B. F. (1991). Value of the Fear Questionnaire in differentiating agoraphobia and social phobia. British Journal of Psychiatry, 159, 842-845. DiNardo, P. A., & Barlow, D. H. (1988). Anxiety Disorders Interview Schedule--Revised (ADIS-R). Albany, NY: Phobia and Anxiety Disorders Clinic, State University of New York. DiNardo, P. A., Moras, K., Barlow, D. H., Rapee, R. M., & Brown, T. A. (1993). Reliability of DSM-III-R Anxiety Disorder category. Archives of General Psychiatry, 50, 251-256. Endler, N. S., Cox, B. J., Parker, J. D. A., & Bagby, R. M. (1992). Self-reports of depression and state-trait anxiety: Evidence for differential assessment. Journal of Personality and Social Psychology, 63, 832-838. Freeston, M. H., Ladouceur, R., Rheaume, J., Letarte, H., Gagnon, F., & Thibodeau, N. (1994). Self-report of obsessions and worry. Behaviour Research and Therapy, 32, 29-36. Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975). Mini-mental state: A practical method for grading the cognitive state of patients for the clinician. Journal of Psychiatric Research, 12, 189-198. Gallo, J. J., Anthony, J. C., & Muthen, B. O. (1994). Age differences in the symptoms of depression: A latent trait analysis. Journal of Gerontology, 49, 251-264. Geer, J. H. (1965). The development of a scale to measure fear. Behaviour Research and Therapy, 3, 45-53. Hersen, M., & Van Hasselt, V. B. (1992). Behavioral assessment and treatment of anxiety in the elderly. Clinical Psychology Review, 12, 619-640. Himmelfarb, S., & Murrell, S. A. (1983). Reliability and validity of five mental health scales in older persons. Journal of Gerontology, 38, 333-339. Kasniak, A. W. (1990). Psychological assessment of the aging individual. In J. E. Birren, & K. W. Schaie (Eds.), Handbook of the psychology of aging (3rd ed., pp. 427-445). New York: Academic Press. Liddell, A., Locker, D., & Burman, D. (1991). Self-reported fears (FSS-II) of subjects aged 50 years and over. Behaviour Research and Therapy, 29, 105-112. Marks, I. M., & Mathews, A. M. (1979). Brief standardized self-rating for phobic patients. Behaviour Research and Therapy, 17, 263-267. Meyer, T. J., Miller, M. L., Metzger, R. L., & Borkovec, T. D. (1990). Development and validation of the Penn State Worry Questionnaire. Behaviour Research and Therapy, 28, 487-495. Mizes, J. S., & Crawford, J. (1986). Normative values on the Marks and Mathews Fear Questionnaire: A comparison as a function of age and sex. Journal of Psychopathology and Behavioral Assessment, 8, 253-262. Murden, R. A., McRae, T. D., Kaner, S., & Bucknam, M. E. (1991). Mini-mental state exam scores vary with education in blacks and whites. Journal of the American Geriatric Society, 39, 149-155. Nunnally, J. C., & Bernstein, I. A. (1994). Psychometric theory (3rd ed.). New York: McGraw-Hill. Oei, T. P. S., Moylan, A., & Evans, L. (1991). Validity and clinical utility of the Fear Questionnaire for Anxiety-Disorder patients. Psychological Assessment: A Journal of Consulting and Clinical Psychology, 3, 391 397. Oxman, T. E., Barrett, J. E., Barrett, J., & Gerber, P. (1987). Psychiatric symptoms in the elderly in a primary care practice. General Hospital Psychiatry, 9, 167-173. Patterson, R. L., Sullivan, M. J., & Spielberger, C. D. (1980). Measurement of state and trait anxiety in elderly mental health clients. Journal of Behavioral Assessment, 2, 89-97. Powers, C. B., Wisocki, P. A., & Whitbourne, S. K. (1992). Age differences and correlates of worrying in young and elderly adults. The Gerontologist, 32, 82-88. Rapee, R. M., & Barlow, D. H. (1991). Chronic anxiety: Generalized anxiety disorder and mixed anxiety-depression. New York: Guilford Press. Regier, D. A., Boyd, J. H., Burke, J. D., Rae, D. S., Myers, J. K., Kramer, M., Robins, L. N., George, L. K., Karno, M., & Locke, B. Z. (1988). One-month prevalence of mental disorders in the United States: Based on five epidemiologic catchment area sites. Archives of General Psychiatry, 45, 977-986. Robinson, J. P., Shaver, P. R., & Wrightman, L. S. (1991). Criteria for scale selection and evaluation. In J. P. Robinson, P. R. Shaver, & L. S. Wrightman (Eds.), Measures of personality and socialpsychological attitudes (pp. 1-16). New York: Academic Press. Sanavio, E. (1988). Obsessions and compulsions: The Padua Inventory. Behaviour Research and Therapy, 26, 169-177. Sanderson, W. C., & Wetzler, S. (1991). Chronic anxiety and generalized anxiety disorder: Issues in comorbidity. In R. M. Rapee, & D. H. Barlow (Eds.), Chronic anxiety: Generalized anxiety disorder and mixed anxiet.v-depression (pp. 119-135). New York: Guilford Press. Seibel, D. W. (1968). Measurement of aptitude and achievement. In D. K. Whitta (Ed.), Handbook of measurement and assessment in behavioral sciences (pp. 261-305). Reading, MA: Addison-Wesley. Sheikh, J. I. (1991). Anxiety rating scales for the elderly. In C. Salzman, & B. D. Lebowitz (Eds.), Anxiety in the elderly (pp. 251-260). New York: Springer. Spielberger, C. D., Gorsuch, R. C., & Lushene, R. E. (1970). Manual for the State-Trait Anxiety Inventor)'. Palo Alto, CA: Consulting Psychologists Press. Sternberger, L. G., & Burns, G. L. (1990). Obsessions and compulsions: Psychometric properties of the Padua Inventory with an American college population. Behaviour Research and Therapy, 28, 341-345. Tanaka-Matsumi, J., & Kameoka, V. A. (1986). Reliabilities and concurrent validities of popular self-report measures of depression, anxiety, and social desirability. Journal of Consulting and Clinical Psychology, 34, 328-333. Trull, T. J., & Hillerbrand, E. (1990). Psychometric properties and factor structure of the Fear Questionnaire Phobia Subscale items in two normative samples. Journal of Psychopathology and Behavioral Assessment, 12, 285-297.
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Turner, S. M., Beidel, D. C., & Stanley, M. A. (1992). Are obsessional thoughts and worry different cognitive phenomena? Clinical Psychology Review, 12, 257-270. Van Oppen, P. (1992). Obsessions and compulsions: Dimensional structure, reliability, convergent and divergent validity of the Padua Inventory. Behaviour Research and Therapy, 30, 631-637. Weissman, M. M., Myers, J. K., Tischler, C. E., Holzer, C. E., Leaf, P. J., Orvaschel, H., & Brody, J. A. (1985). Psychiatric disorders (DSM-III) and cognitive impairment among the elderly in a U.S. urban community. Acta Pschiatrica Scandanavia, 71, 366-379. Wisocki, P. A. (1988). Worry as a phenomenon relevant to the elderly. Behavior Therapy, 19, 369-379. Wisocki, P. A., Handen, B., & Morse, C. K. (1986). The Worry Scale as a measure of anxiety among homebound and community active elderly. The Behavior Therapist, 5, 91-95.
Pergamon
Behav. Res. Ther. Vol. 34, No. 10, pp. 827-838, 1996 Copyright ~c~ 1996 Elsevier Science Ltd Printed in Great Britain. All rights reserved S0005-7967(96)00064-2 0005-7967/96 $15.00 + 0.00
PSYCHOMETRIC PROPERTIES OF FOUR ANXIETY MEASURES IN OLDER ADULTS MELINDA A. STANLEY *~, J. GAYLE BECK2 and BARBARA J. ZEBB2 ~University of Texas Health Science Center, 1300 Moursund Avenue, Houston, TX 77030-3497, U.S.A. and :State University of New York, Buffalo, NY 14260, U.S.A. (Received 7 May 1996)
Summary--Despite relatively high prevalence rates of anxiety disorders in older adults, little attention has been paid to the establishment of psychometrically sound measures for this population. The current study addresses this issue by examining the psychometric properties of four self-report anxiety measures: the Spielberger State-Trait Anxiety Inventory (STAI), Worry Scale (WS), Fear Questionnaire (FQ), and Padua Inventory (PI). Two older adult community subsamples were assessed, one with Generalized Anxiety Disorder (GAD; n = 50) and the other with no anxiety complaints (Normal Controls: NC; n = 94). Descriptive data revealed that mean scores in the GAD sample were similar to those reported in studies of younger GAD patients. Mean scores in the NC sample, however, were lower than those reported in studies of younger control samples. Internal consistency for all measures generally was adequate in both the GAD and NC subsamples, although alpha coefficients for two of the FQ subscales were marginal. Test-retest reliability over a 2~, week interval (assessed in a subgroup of NC subjects) was mixed, with some measures apparently assessing stable, trait-like dimensions of fear and anxiety, and others estimating more state-like clinical features. Intercorrelations among subscales for all four measures in both the GAD and NC groups generally were high and consistent with findings from prior research. Finally, some support for the convergent validity of the four anxiety measures was obtained, particularly in the NC sample. Results are discussed in terms of the utility of these instruments for future investigations of the psychopathology and treatment of anxiety disorders in the elderly. Copyright © 1996 Elsevier Science Ltd
INTRODUCTION Anxiety disorders pose a significant public health problem for older adults, with 1- and 6-month prevalence rates of 4.6% and 6.8%, respectively (Regier et al., 1988; Weissman et al., 1985). Despite these relatively high figures, empirical data addressing the nature and treatment of anxiety in the elderly have only begun to emerge. Of central importance to future investigations in this domain is the establishment of psychometrically sound anxiety measures for older adults. Unfortunately, little attention has been paid to this issue, and the few existing studies are limited by diagnostically heterogeneous samples and the omission of semistructured interview procedures to classify Ss (Hersen & Van Hasselt, 1992). In younger adults, a wide range of instruments has been established to measure anxiety symptoms in samples with and without anxiety disorders [e.g. Fear Survey Schedule (FSS: Geer, 1965); State-Trait Anxiety Inventory (STAI: Spielberger, Gorsuch & Lushene, 1970)]. As such, initial steps toward the development of comparable assessment strategies for older adults might involve examination of the psychometric properties of these same instruments. Early investigations in this domain evaluated the utility of the STAI in samples of community-dwelling older adults and elderly psychiatric inpatients and outpatients (Himmelfarb & Murreil, 1983; Patterson, Sullivan & Whitbourne, 1980). Although these studies demonstrated some support for the reliability and validity of the STAI, conclusions were limited by the use of diagnostically heterogeneous clinical samples and the omission of structured interview assessments (Hersen & Van Hasselt, 1992). In addition, available data have not yet addressed the psychometric properties of other commonly-used anxiety measures in samples of older adults. An alternative psychometric assessment strategy involves the development of new instruments specifically targeting anxiety symptoms in the elderly. For example, Wisocki and colleagues *Author for correspondence. 827
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developed the Worry Scale (WS: Wisocki, Handen & Morse, 1986), a 35-item self-report measure that assesses financial, health, and social worries commonly associated with aging. Preliminary reports provided mean scores and some support for the concurrent validity of the WS in community-dwelling and homebound older adults based on given significant correlations with other self-report measures of anxiety (Wisocki et al., 1986; Wisocki, 1988). An additional study compared WS scores in older and younger samples (Powers, Wisocki & Whitbourne, 1992). However, internal consistency and test-retest reliability have not been examined, and the samples used in these reports were community residents. Thus, the applicability of the WS for well-diagnosed clinical and nonclinical samples is unknown. To set the stage for future investigations of psychopathology and treatment in anxious older adults, it is necessary to examine the psychometric properties of a variety of available instruments in well-diagnosed clinical and community samples of older adults (Hersen & Van Hasselt, 1992; Sheikh, 1991). In an initial investigation in this regard, the reliability and validity of the Penn State Worry Questionnaire (PSWQ: Meyer, Miller, Metzger & Borkovec, 1990) were examined in 47 older adults with Generalized Anxiety Disorder (GAD) and 94 normal control (NC) Ss, ages 55-82 (Beck, Stanley & Zebb, 1995). All Ss were classified using the Anxiety Disorders Interview Schedule--Revised (ADIS-R: DiNardo & Barlow, 1988), a semistructured interview designed to assist in the diagnosis of anxiety and affective disorders. Results revealed adequate internal consistency (coefficient ~ > 0.80) and convergent validity, as documented by significant correlations with related self-report measures of anxiety, for the PSWQ in both GAD and NC groups. Similar investigations are needed to examine other commonly-used self-report anxiety measures in older patient and control samples. In this regard, further examination of measures that target clinical features of individuals with GAD would be particularly useful. Recent epidemiological data have suggested that GAD is one of the most prevalent of the anxiety disorders in older adults, with 6-month and lifetime rates of 1.9% and 4.6% (Blazer, George & Hughes, 1991). Given these figures, along with the pervasiveness and chronicity of GAD (Rapee & Barlow, 1991), further investigation of the nature and treatment of generalized anxiety and associated symptoms in the elderly is warranted. Prior to such investigations, well-validated measures of relevant clinical features will need to be established. These measures should address the severity of worry, a core feature of GAD (American Psychiatric Association, 1987, 1994), as well as general feelings of anxiety. As noted above, prior data have addressed the psychometric properties of the PSWQ, an established self-report measure of worry, in well-diagnosed samples of older adults. However, further examination of the WS, a measure targeting worries commonly associated with aging, and the STAI, a well-established measure of general anxiety, are still needed. Specifically, examination of reliability and validity of these instruments is needed in well-diagnosed GAD and normal samples of older adults. In addition, given the proposed overlap between worry and obsessionality (Freeston, Ladouceur, Rheaume, Letarte, Gagnon & Thibodeau, 1994; Turner, Beidel & Stanley, 1992), as well as the high prevalence of coexistent social and simple phobias in GAD (Sanderson & Wetzler, 1991), measures to assess severity of obsessions and related fears also need to be established. In this regard, psychometric evaluation of the Padua Inventory (PI: Sanavio, 1988), a questionnaire evaluating the severity of obsessions and compulsions, and the Fear Questionnaire (FQ: Marks & Mathews, 1979), a measure of avoidance related to social, agoraphobic, and blood injury fears, would be useful. As such, the present study evaluated the psychometric properties of four self-report instruments: WS, STAI, PI and FQ. Participants included two groups of community-dwelling older adults, one without anxiety complaints and one with GAD, both classified according to the ADIS-R.
METHOD Participants Generalized anxiety disorder (GAD) subsample. Demographic information on the samples is shown in Table 1. The GAD subsample included 50 older adults, ages 55-81, who met DSM-III-R criteria for GAD (American Psychiatric Association, 1987). Age distribution of the sample was as follows: 55-59 (16%); 60-64 (12%); 65 and older (72%). Prospective participants were recruited
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Table 1. Demographic data for older adults with generalized anxiety disorder (GAD) and a subsample of normal controls (NC)
Age: Mean (SD) Education: Mean (SD) Gender Female Ethnicity Caucasian African-American Hispanic Native American Marital Status Married Divorced Widowed Single
G A D subsample (n = 50)
NC subsample (n = 94)
67.92 yr (6.81) 14.46 yr (2.79)
67.53 yr (6.77) 15.20 yr (2.24)
72.0% (n = 36)
69.1% (n = 65)
82.0% 14.0% 2.0% 2.0%
(n (n (n (n
= = = =
41) 7) 1) 1)
95.7% (n = 90) 2.1% (n = 2) 2.1% (n = 2) 0
66.0% 16.0% 14.0% 4.0%
(n (n (n (n
= = = =
33) 8) 7) 2)
62.8% 17.0% 17.0% 3.2%
(n (n (n (n
= = = =
59) 16) 16) 3)
with media announcements, as well as visits to community agencies and church groups for older adults, and were screened initially by telephone. Those individuals whose symptoms appeared to fit GAD criteria were then interviewed using the ADIS-R by advanced-level graduate students who received extensive training in the administration of this instrument (DiNardo, Moras, Barlow, Rapee & Brown, 1993). Participants who reported current use of psychotropic medication, with the exception of occasional hypnotics for sleep difficulties (i.e. less than four times per week), were asked to withdraw from these regimes under supervision of the prescribing physician, with at least a 2-week clearance prior to administration of the ADIS-R. Exclusion criteria included: primary diagnosis of an alternate Axis I disorder, current involvement in psychotherapy, serious medical conditions (e.g. recent stroke, acute cardiac disease, or Parkinson's disease), alcohol or substance abuse within the previous 6 months, psychotic symptoms, or evidence of cognitive impairment according to a score of 24 or lower on the Mini-Mental State examination (Folstein, Folstein & McHugh, 1975)*. All ADIS-R interviews were videotaped, with a random 28% (n = 14) selected for evaluation by a second clinician to estimate interrater agreement. One-hundred per cent diagnostic agreement was noted for GAD, most likely due to extensive prescreening of potential participants and the use of videotaped interviews rather than administration of two separate ADIS-Rs (Borkovec & Costello, 1993). Secondary diagnoses were as follows: Social Phobia 16% (n = 8), Simple Phobia 12% (n = 6), Major Depression 12% (n = 6), Panic Disorder 10% (n = 5), Dysthymia 4% (n = 2), and Post Traumatic Stress Disorder 2% (n = 1). Kappa coefficients for secondary diagnoses indicated excellent reliability (1.00) for Social Phobia, Simple Phobia, and Panic Disorder, and moderate reliability (0.58) for Major Depression. Other diagnoses did not occur with sufficient frequency in the reliability sample to allow calculation of kappa coefficients. Normal control (NC) subsample. The NC subsample included 94 adults, ages 55-82, without any DSM-III-R Axis I diagnosis. Age distribution mirrored that of the GAD group, with frequencies as follows: 55-59 (16%); 60-64 (12%); 65 and older (72%). These individuals were recruited in the same fashion as the GAD subsample, and initial telephone screenings were followed by administration of the ADIS-R to confirm the absence of any Axis I disorder. Other exclusion criteria for this group were similar to those noted for the GAD group. Measures
All GAD and NC participants completed the Spielberger State-Trait Anxiety Inventory (STAI; Spielberger et al., 1970), the Worry Scale (WS; Wisocki et al., 1986), the Padua Inventory (PI; Sanavio, 1988), and the Fear Questionnaire (FQ; Marks & Mathews, 1979). The STAI is a well-known 40-item instrument which includes both state and trait scales, measuring respectively transient and enduring levels of anxiety. Strong psychometric support is available for the STAI with younger adults (Spielberger et al., 1970), and preliminary data from *A c u t - o f f s c o r e o f 17 w a s used f o r i n d i v i d u a l s w i t h a n e i g h t h g r a d e o r less e d u c a t i o n ( M u r d e n , M c R a e , K a n e r & B u c k n a m , 1991).
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heterogeneous community and psychiatric samples of older adults suggest adequate internal consistency and convergent validity (Himmelfarb & Murrell, 1983; Patterson et al., 1980). The WS is a 35-item questionnaire developed to assess severity of financial, health, and social worries in older adults (Wisocki et al., 1986). As noted above, although mean scores from community dwelling and homebound elderly are available (Powers et al., 1992; Wisocki et al., 1986; Wisocki, 1988), few psychometric data have been reported. The FQ is a 15-item inventory assessing severity of avoidance related to agoraphobic, social, and blood-injury fears. Psychometric data for this instrument in younger adults with and without anxiety are adequate (Marks & Mathews, 1979; Trull & Hillerbrand, 1990; Oei, Moylan & Evans, 1991), but the FQ has not been used with older adults. The PI is a 60-item questionnaire designed to evaluate obsessive-compulsive symptoms. Four subscales assess severity of contamination and checking rituals, as well as fears of losing control over mental activities and motor behaviors. Psychometric support for this instrument in younger patient and control samples is good (Sternberger & Burns, 1990; Van Oppen, 1992). The PI has not been used previously with older adults.
Procedure Following evaluation of inclusion/exclusion criteria, participants in the G A D subsample completed the measures described above as part of a broader pretreatment evaluation.* NC participants completed these same instruments in the context of a briefer evaluation and were paid $50 for their participation. All participants provided informed consent, and demographic data for both groups are presented in Table 1. For a subset of NC participants (n = 46), questionnaires were readministered 2~4 weeks later ( X = 19.0 days, SD = 7.1) to allow evaluation of test-retest reliability. Although this test retest interval was somewhat variable due to scheduling difficulties, the majority of participants (76%) were re-evaluated within 3 weeks of the initial testing. RESULTS
Data analytic strategies All psychometric analyses for the STAI, WS, PI and FQ were conducted separately for the G A D and NC samples.? Within each group, gender differences for each anxiety measure were examined, and mean scores were compared to those from similar samples of younger adults using z-score comparisons of means. Internal consistency for each measure was then estimated with coefficient alpha, calculated separately for subscale and total scores of each instrument. Also within each sample, the interrelationships of subscale scores for each measure were examined with Pearson r correlation coefficients and statistical comparisons of dependent rs (Cohen & Cohen, 1983). Convergent validity was examined with Pearson r correlation coefficients assessing the interrelationships of scores on the four measures. In an attempt to control for experimentwise error rate, the nominal alpha for these correlations was set to 0.01. For the subset of NC Ss to whom the questionnaires were administered a second time, test-retest reliability was estimated with Pearson r correlation coefficients. Again, correlations were calculated separately for subscale and total scores of each measure.
G A D subsample Descriptive data. Means and standard deviations for the STAI, WS, FQ and PI in the G A D subsample are included in Table 2. No significant gender differences were noted on any measure, *It should be noted that questionnaire data were unavailable for 2 of the 50 Ss in the GAD group. tStatistical comparisons of scores between the GAD and NC subsamples will not be addressed here given some overlap with a separate report intended to document the psychopathologicalfeatures of GAD in older adults relative to a matched sample of NC participants (Beck, Stanley & Zebb, 1996). In that study, matched subgroups of the samples included here were compared with regard to various clinical features (e.g. anxiety, depression, associated fears) to provide a description of the nature of GAD and coexistent symptomatologyin older adults. It should be noted that the primary foci of these two studies are different. Additionally, the NC subsample described here is twice as large as the matched group, and the psychopathologywork utilized a broader range of measures than those described here. However, to avoid the presentation of any potentially redundant data in the two reports, direct comparison of scores in the GAD and NC subsamples were omitted here.
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Table 2. Mean scores, standard deviations, and coefficient alphas for four measures of anxiety in older adults with generalized anxiety disorder (GAD subsample; n = 50) Measure STAI A-State (20 items) A-Trait (20 items) WS Social (13 items) Finances (5 items) Health (17 items) Total (35 items) FQ Blood-Injury (5 items) Agoraphobia (5 items) Social Phobia (5 items) Total (15 items) PI Mental Control (17 items) Contamination (11 items) Checking (8 items) Behavior Control (7 items) Total (60 items)
Mean (SD)
Possible range
:t
45.0 (13.1) 48.0 (I 1.9)
20-80 20-80
0.94 0.88
13.2 4.1 18.3 35.4
(9.5) (3.6) (10.5) (20.9)
0-52 0-20 0-68 0-140
0.91 0.76 0.86 0.93
9.7 6.8 9.9 26.1
(6.3) (5.5) (6.2t (14,5)
0-40 0-40 0~.0 0--120
0.73 0.61 0.67 0.82
12.8 8.0 5.7 0.9 31.0
(11.4) (6.71 (5.5) (1.8) (21.8)
0-68 0-44 0-32 0-28 0-240
0.90 087 0.85 0.74 0.95
STAI = State-Trait Anxiety Inventory; WS = Worry Scale; FQ = Fear Questionnaire; PI = Padua Inventory.
Note:
so means were collapsed across this variable. Scores on the STAI-Trait subscale and FQ-Total scale in the older adult GAD group were similar to those reported in studies of younger adults with GAD [ Barlow, Rapee & Brown, 1992 (mean age = 40.6 yr); STAI-Trait: z = 1.32, NS; FQ: z = 0.68, NS]. Scores on the WS in the GAD subsample, however, were significantly higher than those reported in community samples of elders [ Powers et al., 1992 (mean age = 77.6 yr); Wisocki, 1988 (mean age = 72.0 yr); z = 2.42-3.31, P < 0.05]. Internal consistency. Alpha coefficients (see also Table 2) indicated adequate to strong internal consistency for all subscale and total scores of the STAI, WS, and PI (Nunnally & Bernstein, 1994; Robinson, Shaver & Wrightman, 1991). Internal consistency for the FQ Blood-Injury and Total scores also were adequate, although coefficients for the Agoraphobia and Social Phobia subscales were marginal. Examination of item-remainder correlations revealed a range of 0.31-0.48 for the Agoraphobia subscale and 0.29-0.60 for the Social Phobia subscale. In neither case did the deletion of any one item improve internal consistency. Interrelationships ofsubscales. Intercorrelations of subscale scores for the anxiety measures in the GAD subsample are presented in Table 3. As noted in prior reports with both older and younger samples (e.g. Endler, Cox, Parker & Bagby, 1992; Patterson et al., 1980; Tanaka-Matsumi & Kameoka, 1986), the STAI State and Trait subscales correlated significantly. In addition, all WS subscale scores correlated significantly with each other and with the Total score. However, the Finances subscale was less strongly related to Total WS scores than were the Social or Health subscales (correlation of dependent rs; P < 0.025), a finding that is consistent with prior research (Powers et al., 1992). The weaker relationship between financial worries and total WS scores may result from the relatively small number of items that comprise the Finances subscale (see Table 2). Intercorrelations for the FQ revealed that the Agoraphobia subscale correlated significantly with both the Blood-Injury and Social Phobia subscales, although the latter two measures were unrelated (see Table 3). However, each of the FQ subscales correlated similarly with Total FQ scores (comparisons of dependent rs; all Ps > 0.10). Finally, significant relationships were noted between the PI-Mental Control, Contamination, and Checking subscales (see Table 3). The Behavior Control subscale also correlated significantly, but less strongly, with the Mental Control and Checking subscales, but was unrelated to the Contamination subscale. This pattern is congruent with prior research in younger samples (Van Oppen, 1992). Finally, all PI subscale scores correlated similarly with the Total score (comparisons of dependent rs; all Ps > 0.10). Convergent validity. Intercorrelations of the anxiety measures in the GAD subsample are presented in Table 4. Significant positive correlations were obtained between the STAI-Trait, WS, and PI, demonstrating adequate convergent validity among measures of trait anxiety, worries, and
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Table 3. lntercorrelations of subscale scores for the STAI, WS, FQ, and PI in the G A D subsample (n = 50) STAl-State STAI-Trait WS Social Finances Health FQ Blood-Injury Agoraphobia Social Phobia PI Mental Control Contamination Checking Behavior Control
0.74** Finances 0.58**
Health 0.75** 0.46**
Agoraphobia 0.59**
Social Phobia 0.27 0,49**
Contamination 0.55*
Checking 0.80** 0.60**
Total 0.93** 0.67** 0.92** Total 0.77** 0,84** 0.74** Behavior Control 0.42* -0.03 0.40*
Total 0.70** 0.56** 0.58** 0.57**
*P < 0.01; **P < 0,001. Table 4. Intercorrelations of anxiety measures in the G A D subsample (n = 50) WS-Total STAI State Trait WS-Total PI-Total
0.22 0.40*
PI-Total
FQ°Total
0.21 0.44* 0.46**
0.16 0.34 0.24 0.12
*P < 0.01; **P < 0,001
obsessive-compulsive symptoms in older adults with GAD (Seibel, 1968). The STAI-State and FQ scales, however, failed to correlate significantly with other measures of anxiety.
NC subsample Descriptive data. Means and standard deviations for the STAI, WS, FQ, and PI in the NC subsample are reported in Table 5. Again, no significant gender differences emerged on any of these measures. Table 5 also includes representative mean scores from other literature with younger adult control samples. Comparison of means in the two groups revealed significant differences on all measures, with older adults scoring consistently lower than younger samples (see z-scores, Table 5). Internal consistency. Coefficient alphas (Table 6) indicated adequate to strong internal consistency for subscale and total scores in the NC subsample (Nunnally & Bernstein, 1994; Robinson et al., 1991), with the exception of the FQ-Social Phobia and PI-Behavior Control subscales. For the FQ-Social Phobia subscale, item-remainder correlations ranged from 0.25 to Table 5. Mean scores on four measures of anxiety in older adults without psychiatric diagnoses (NC subsample; n = 94) and younger adult normal controls Measure STAI State Trait WS Social Finances Health Total FQ Blood-Injury Agoraphobia Social Phobia Total PI Mental Control Contamination Checking Behavior Control Total
Older adults
Younger adults'
z-score comparison of means b
26.5 (6.8) 26.8 (5.7)
35,8 (9.5) 37.9 (9.4)
11.34 15.42
4.0 1.1 6.0 11.0
(4.3) (1.7) (5,8) (10.4)
13.3 5.4 14.0 32.6
(8.0) (3.6) (8.2) (17.7)
9.03 9.55 7.08 9.31
5.2 3.6 4.9 13.6
(5.2) (4.3) (3.7) (10.9)
8.1 4.9 8.8 24,9
(6.2) (5.6) (5.8) (16.0)
4.03 2.10 6.61 6.81
3.0 4.0 2.2 0.2 12.4
(3.7) (4.6) (3.0) (0.6) (12.3)
----41.3 (25.8)
18.06
'Younger adult scores taken as follows: (1) STAI (Spielberger et al., 1970; 484 college undergraduates); (2) WS (Powers et al., 1992, 74 college undergraduates, mean age = 20.4 yr); (3) FQ (Mizes & Crawford, 1986; 172 adults, mean age ffi 41.5 yr); (4) PI (Sternberger & Burns, 1990; 701 college undergraduates, mean age = 18.9 yr). bAll :-scores significant at P < 0.05.
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833
Table 6. Coefficient alphas and test-retest (2-4 weeks) correlation coefficients for four measures of anxiety in the NC subsample Measure
Coefficient x (n = 94)
Test-retest coefficient (n = 46)
0.85 0.79
0.62 0.84
0,88 0.80 0.91 0.94
0.76 0.80 0.58 0.69
0.79 0.74 0.60 0.85
0,57 0.41 0.64 0.52
0.79 0.86 0.85 0.19 0.91
0.61 0.79 0.64 0.75 0.80
STAI State (20 items) Trait (20 items) WS Social (13 items) Finances (5 items) Health (17 items) Total (35 items)
FQ
Blood-lnjury (5 items) Agoraphobia (5 items) Social Phobia (5 items) Total 115 items) PI Mental Control (17 items) Contamination (11 items) Checking (8 items) Behavior Control (7 items) Total (60 items)
0.54, and no significant improvement in internal consistency occurred following deletion of any single item. Item-remainder correlations for the PI-Behavior Control subscale ranged from - 0.05 to 0.27. Deletion of item 57 ("I feel I have to make special gestures or walk in a certain way") increased coefficient alpha (from 0.19 to 0.36), although inadequate internal consistency was still noted. Examination of frequency distributions for items on the PI-Behavior Control subscale also revealed that over 90% of NC participants scored zero on each, suggesting that restricted range may have contributed to poor internal consistency of this subscale.
Test-retest reliability. Correlation coefficients (Table 6) indicated strong test-retest reliability for the STAI-Trait and a weaker relationship over time for scores on the STAI-State, as might be expected, although statistical comparison of these correlations revealed no significant difference (z = 1.00, NS). Test-retest reliability for the WS generally was adequate, with the exception of the Health subscale. On this subscale, however, post hoc paired comparisons revealed no significant differences in scores at times 1 and 2, suggesting no consistent pattern of change in health-related worries over time. In general, subscale and total scores on the FQ were not stable over time. Post hoc comparisons of means on this measure revealed significantly lower scores at time 2 than time 1 for Agoraphobia, Social, and Total scores, suggesting a consistent pattern of change over time. Test-retest reliability for the PI was somewhat inconsistent, with adequate coefficients demonstrated for Contamination, Behavior Control, and Total scores, but only marginal stability for subscales measuring Mental Control and Checking. Post hoc paired comparisons of these measures revealed no consistent pattern of change from time 1 to time 2. Interrelationships of subscales. Intercorrelations of subscale scores for the STAI, WS, FQ, and PI in the NC subsample are presented in Table 7. As in the GAD subsample, STAI-State and Trait subscales were significantly correlated. All WS subscale scores also correlated significantly with Table 7. Intercorrelations of subscale scores for the STAI, WS, FQ and PI in the NC subsample (n = 94) STAI-Trait WS Social Finances Health FQ Blood-Injury Agoraphobia Social Phobia PI Mental Control Contamination Checking Behavior Control *P < 0.01; **P < 0.001.
STAI-State 0.74** Finances 0.44**
Health 0.80** 0.42**
Agoraphobia 0.50**
Social Phobia 0.47** 0.65**
Contamination 0.45**
Checking 0.57** 0.64**
Total 0.92** 0.58** 0.95** Total 0.83** 0.85** 0.82** Behavior Control 0.49** 0.19 0.26
Total 0.84** 0.77** 0.83** 0.48**
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Table 8. Intercorrelations of anxiety measures in the NC subsample (n = 94)
STAI State Trait WS-Total PI-Total
WS-Total
P1-Total
FQ-Tota!
0.41"* 0.57**
0.48** 0.57** 0.50**
0.38** 0.43** 0.34** 0.62**
**P < 0.001.
each other and with the Total score, although the Finances subscale again was less strongly related to the Total than were the Social or Health subscales (comparison of dependent rs; P < 0.005). Intercorrelations for the FQ revealed that all subscales correlated significantly with each other, and each related similarly to the Total FQ score (comparisons of dependent rs; all P > 0.10). Finally, significant relationships were noted between the PI Mental Control, Contamination, and Checking subscales (Table 7). The Behavior Control subscale, however, correlated only with the Mental Control subscale; it was unrelated to the Contamination and Checking subscales. Further, the Behavior Control subscale correlated less strongly with the Total PI score than the other three subscales (comparison of dependent rs; P < 0.025). Convergent validity. Intercorrelations among the anxiety measures in the NC subsample are presented in Table 8. Significant correlations were observed among all measures of anxiety, demonstrating adequate convergent validity between measures of state and trait anxiety, worries, obsessive-compulsive symptoms, and specific fears (Seibel, 1968). DISCUSSION The goal of the present study was to investigate the psychometric properties of four measures of anxiety (STAI, WS, FQ, PI) in older adults with and without anxiety complaints. All Ss were selected for participation according to the ADIS-R, and psychometric analyses addressed descriptive data, internal consistency, test-retest reliability, interrelationships of subscales, and convergent validity. Examination of descriptive data indicated no gender differences on any of the four measures in either the GAD or NC subsamples. Although gender differences on some of these measures have been reported for younger adult samples (e.g. Mizes & Crawford, 1986; Sanavio, 1988), the current study suggests that gender differences on measures of anxiety may not be significant in older anxious and non-anxious adults. When possible, mean scores in the older adult GAD group were compared with those from younger GAD samples. Results revealed no significant differences, suggesting some degree of overlap in the symptom pictures of younger and older GAD patients. These results must be interpreted cautiously, however, given that equivalent mean scores do not necessarily indicate similar patterns of symptoms. It is possible that older adults are more likely to report certain types of symptoms (e.g. somatic) than younger samples. Age-related differential symptom patterns, in fact, have been reported in the depression literature. In particular, older adults are less likely to endorse symptoms of dysphoria or anhedonia and more likely to acknowledge sleep impairment, thoughts of death, and passive suicidal ideation than younger adults even at similar levels of depression (Gallo, Anthony & Muthen, 1994). Comparisons between the older adult NC group and younger normal control samples revealed consistently lower scores in the elderly. The meaning of this finding is unclear, however, given that older adult NC participants were selected via diagnostic interviews to be free of any psychiatric disorder, unlike selection procedures for younger adult control samples. It is possible, therefore, that differences reported here are the result of heterogeneous younger adult 'normal' groups wherein some proportion of participants met criteria for psychiatric disorders. Differences in educational, social, and other demographic data also could account for the apparent divergence in symptoms reported by older and younger samples. On the other hand, the notion that normal samples of older adults report fewer anxiety complaints than younger control samples cannot be disregarded. In fact, epidemiological data have shown lower rates of anxiety disorders in older adults relative to younger samples (Regier et al., 1988). In addition, Wisocki et al. (1986) reported relatively few worries overall in a sample of community-dwelling normal adults, and Powers et al.
Anxietymeasures
835
(1992) documented significantly fewer worries in a similar sample relative to a group of college undergraduates. Although it is possible that non-anxious elderly individuals genuinely worry less than younger adults, the tendency of older adults to under-report worries also should be considered (Oxman, Barrett, Barrett & Gerber, 1987). Examination of internal consistency revealed adequate alpha coefficients for subscale and total scores for the STAI, WS, and PI in both groups, with the exception of the PI-Behavior Control subscale in the NC subsample wherein the small number of items (n = 7) and restricted range of scores may have contributed to subscale instability. As such, the data suggest that these measures generally assessed the constructs of worry, state and trait anxiety, and obsessive-compulsive complaints in a reliable fashion for older adults with and without GAD. In addition, estimates of internal consistency for the FQ Total and Bodily Injury subscales revealed adequate reliability in both GAD and NC older adults. Alpha coefficients for the FQ Social Phobia subscale in both groups, however, and the FQ Agoraphobia subscale in the GAD group were marginal. It should be noted that estimates of internal consistency for the FQ subscales in younger adult anxious and non-anxious samples also have not been consistently high (Cox, Swinson & Shaw, 1991; Trull & Hillerbrand, 1990), suggesting that these subscales may not provide consistently reliable evaluations of specific phobias in any age group. The small number of items comprising each subscale (n = 5) may contribute to these marginal coefficients in both younger and older samples. Nonetheless, further investigations of this measure in older adults with different anxiety disorders, particularly those characterized by specific fears or phobias (Liddell, Locker & Burman, 1991), would be useful. Coefficients of test-retest reliability (assessed in a subsample of NC Ss) were mixed, with some measures apparently assessing stable, trait-like dimensions of fear and anxiety, and others estimating more state-like clinical features. Of particular interest in this regard, worries about financial and social concerns remained consistent over the 2-4 week retest interval, but health-related worries were unstable over time. It is possible that the WS Health subscale assessed sensitivity to real physical complaints which varied over time for non-anxious older adults, whereas financial and social issues remained more stable for individuals in this group. The failure of post hoc comparisons to document a significant difference in WS Health scores over time is consistent with this hypothesis. All FQ scores also indicated poor stability over time, suggesting that this measure of social, agoraphobic, and bodily-injury fears may have varied in a state-like fashion for older adults without anxiety complaints. Post hoc comparisons, however, revealed a consistent pattern of decreasing fear over time, indicating the possibility of regression on this measure. These data highlight the need for further investigations into the measurement of specific fears for older adults. Although test-retest reliability for all anxiety measures has yet to be investigated in older adults with GAD, data from NCs suggest the potential need for development of alternative measures of specific fears for the elderly since the FQ may be unreliable in this population. The impact of a somewhat variable test-retest interval on estimates of stability for all instruments also must be considered. Intercorrelations among subscales for all anxiety measures in both the GAD and NC groups generally were high and consistent with findings from prior research (e.g. Endler et al., 1992; Patterson et al., 1980; Van Oppen, 1992). However, the severity of financial worries was less strongly correlated with WS Total scores than other WS subscales in both GAD and NC groups, possibly due to the smaller number of items comprising the Finances subscale. It also is possible, however, that financial concerns in the elderly are somewhat independent of other worries. In both participant groups, fears of losing control over motor behaviors also were somewhat independent from other dimensions of obsessive-compulsive symptomatology measured by the PI (e.g. contamination fears, fears of loss of control over mental function, and checking behaviors). Although this finding is similar to that reported in younger adults (Van Oppen, 1992), the relative independence of fears related to loss of motor control in the subsamples assessed here may probe real-life concerns about loss of motor function in advanced age. However, the restricted range of scores on this subscale also may explain the lack of relationship with other measures of obsessive-compulsive complaints. Participants in this study (both GAD and NC) reported very few concerns about loss of control over motor behaviors. Some support for the convergent validity of the four anxiety measures was obtained, particularly in the NC subsample. In that group, all correlations among the four measures of anxiety were BRT 34']0--F
836
Melinda A. Stanleyet al.
statistically significant, suggesting some degree of relatedness among measures of various anxiety symptoms in non-anxious older adults. In the GAD group, significant correlations were obtained among the WS, STAI-Trait, and PI, indicating convergence among measures of worry, trait anxiety, and obsessionality. Overlap in these clinical features has been noted in prior literature (e.g. Freeston et al., 1994; Turner et al., 1992). The STAI-State and FQ, however, failed to correlate significantly with other measures of anxiety, suggesting that for older adults with GAD, state anxiety and specific fears or phobias may be unrelated to severity of worry, trait anxiety, and obsessive-compulsive symptoms. It is also possible, however, that lower reliability coefficients for these measures may account for the failure to document convergent validity. Lack of convergence in these cases may result from the fact that some aspects of anxiety associated with GAD represent stable, trait-like features, whereas others appear to be more state-like clinical characteristics, as noted earlier. It also should be noted that conclusions regarding convergent validity in general are limited by the omission of measures that would allow examination of divergent validity (e.g. measures of depression). In summary, empirical support for the psychometric properties of the WS, STAI, and PI was obtained in well-diagnosed older adults with and without anxiety complaints. These measures, along with the PSWQ (Beck et al., 1995), should be useful for future investigations of psychopathology and treatment in older anxious adults. Additional data are needed, however, to address discriminant validity, i.e. the utility of these measures for differentiating older adults with G A D from those with other anxiety disorders (e.g. panic disorder, specific phobias), alternate psychiatric syndromes (e.g. depression), or serious medical conditions. Likewise, content validity of the STAI and PI will need to be examined given that these measures were developed for younger samples. As noted by Kasniak (1990), age-related differences in symptom experience may threaten content validity in this regard. This issue is less of a concern for the WS since it was developed to assess worries specific to the experience of older adults. Sensitivity to treatment effects for these measures also has yet to be documented. Reliability data for the FQ suggest that additional consideration should be given to the measurement of specific fears in the elderly. Examination of test-retest reliability in the GAD subsample was omitted here and should be investigated in future research. More broadly, an investigation of psychometric properties of the FQ is needed in samples of older adults whose symptoms meet criteria for various types of phobias. In this regard, issues of content validity will be of particular importance. The utility of other measures of specific fears also should be considered, with particular attention to instruments which utilize a larger number of items to assess related symptoms commonly reported by the elderly. The potential need for development of a new measure that targets fears specific to the elderly also should be considered. Limitations of the present work include the failure to examine test-retest reliability of measures in the GAD subsample, omission of data to address discriminant validity, and the use of small sample sizes that precluded examination of factor structures. In addition, generalizability of the work is limited given that the majority of participants in both groups were well-educated, community-dwelling, Caucasian adults. Future studies will need to address the utility of these measures in samples of more ethnically and socioeconomically diverse elders. Acknowledgements--This researchwas supported in part by a grant from the Texas Higher EducationCoordinatingBoard
(003652-075) awarded to the first and second authors. The authors would like to thank Drs David Lachar, Diane Novy, and John Overall, as well as four anonymousreviewers, who provided commentson earlier versions of this work.
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