Validation of the Scale of Functioning in Older Outpatients With Schizophrenia

Validation of the Scale of Functioning in Older Outpatients With Schizophrenia Mark H. Rapaport, M.D., James Bazzetta, M.A., Lou Ann McAdams, Ph.D., Thomas Patterson, Ph.D., Dilip v: Jeste, M.D. The authors investigated the reliability and validity of the Scale ofFunctioning (SOF), a I5-item scale, in 78 middle-aged and elderly olltpatients with schizophrenia. The SOP score· had both higb internal consistency and high interrater reliability and significantly discriminated between these patients and 45 normal comparison subjects. SOF scores c01Telated significantly with scores on several psychopathology rating scales as well as a nUlnber of existing instruments assessing cognitive orjunctional ability. Principal-components analysis llsing different scales ofjunctional ability, psychopathology, and global cognitive performance and treated by orthogonal rotation revealed twa domains of functioning, one of which was defined by the SOP along with scalesfor activities ofdaily living, negative symptoms, and cognitive ilnpairment. The other domain was defined by scales/or quality of well-being, social adjustment, and positive and depressive symptoms. Results support the construct validity of the SOF in late-life schizophrenia. (American Journal of Geriatric Psychiatry 1996; 4:218-228)

R

eliable and valid methods ofobservation and measurement are essential to the evaluation of functioning and testing of hypotheses related to outcomes in patients with schizophrenia. Scales such as the Brief Psychiatric Rating Scale (BPRS) 1 and the Positive and Negative Syn-

drome Scale (PANSS)2 are excellent at assessing positive and negative symptoms, but give the clinician only limited information about the subject's level of functioning. It has become increasingly apparent that the categorization of signs and symptoms alone does not yield a comprehen-

Received August 2, 1995; revised November 13, 1995; accepted November 15, 1995. From the University of California, San Diego, Department of Psychiatry. Address correspondence to Dr. Rapaport, Psychopharmacology Research Program, Dept. of ()sychiatry, University of California, San Diego, 8950 Villa La Jolla Dr., Suite 2243, L'lJolla, CA 92037. 218

VOLUME 4 • NUMBER 3 • SUMMER 1996

Rapaport et al. sive description of these patients. 3- S The Social Adjustment Scale6 has been used to measure social functioning for a variety of different psychiatric populations, including patients with schizophrenia and depression. Although this scale has several strengths, it uses a general construct that assesses social adjustment in a variety of different disorders. The Quality of WellBeing (QWB) scale' was developed to measure functional disability associated with medical illnesses and is beginning to be used in the assessment of psychiatric disorders. This scale, too, is a general measure of the quality of well-being and is not disorder-specific. The Strauss-Carpenter Scale8 and the Nurses' Observational Scale for Inpatient Evaluation9 address aspects ofsocial functioning in individuals with schizophrenia, but they do not afford the clinician the opportunity to continuously evaluate patients in both inpatient and outpatient settings. Furthermore, the Strauss-Carpenter Scale is not designed for the longitudinal assessment of functioning. 8 Two of the most commonly used instruments for the assessment of functioning in geriatric populations are the Pfeffer Outpatient Disability Scale lO and the Lawton Powell Physical Self..Maintenance Scale. II These scales were developed pri.. marily to assess activities of daily living, rather than social functioning, in nonpsychiatrically ill geriatric populations. Therefore, there is still a need for a comprehensive yet easily administered scale measuring functioning in older individu.. als with schizophrenia. 12-15 We believe that particularly in these times of diminishing resources and fund.. ing, it would be useful to carefully quantify the impact of treatment interventions on health care expenditures through longitudinal studies. This is especially true for individuals with severe mental disorders. Advocates for individuals with severe mental disorders should be able to use carefully quantified and validated instruTHE AMEIUCAN JOURNAL OF GERIATRIC PSYCHIATRY

ments to present their case. Furthermore, it is important for the clinicians, the caregivers, and the patients themselves to be able to assess their functional status in order to measure the success oftheir care. One of the problems with schizophrenia is that the recovery is so slow and the in.. crement of improvement is so small that broader-based measures may be unable to efficiently monitor the success or failure of interventions. We believe that a well..designed, disorder-specific scale may be an important tool to help monitor the course of these patients. The Scale of Functioning (SOF) is a new I5-item clinical scale developed for use in both inpatients and outpatients with schizophrenia. 16,17 A listing of the 15 items that make up the scale is presented in Table 1. Each item on the scale has four anchor points. The minimum and maximum possible total scores on the SOF are 15 and 60 points, respectively: A preliminary analysis of data assessing the reliability and validity of the SOF in younger schizophrenia patients indicates that the scale is reliable and valid in that population. 16•17 It is a relatively brief and userfriendly instrument that can lend itself to repeated assessments of functioning in a longitudinal study of outcome. The goal of the present studywas to detennine whether the SOF is also a reliable and valid clinical tool for the measurement of functioning in older patients with schizophrenia. We assessed two types of reliability (internal consistency and interrater reliability) and two aspects ofconstruct validity (trait validity or trait correspondence, and nomological validity or nomological relatedness).18 We hypothesized that the SOF has both internal consistency and interrater reliability and, from earlier data,16 17 that it would discriminate between the schizophrenia group and control group, and SOF scores (higher scores indicating better functioning) would be inversely correlated with scores on scales of psychopathology severity, especially t

219

Scale ofFunctioning in Schizophrenia TABLE 1.

Scale of Functioning (SOF)

Item 1.

Orientation Patient is disoriented (cannot state name. location, date) 1 Patient is oriented to self/name only 2 Patient is oricnted to name and location 3 4 Patient is oriented to name, location, date Item 2. Grooming/Hygiene 1 Patient is filthy (has not changed clothes or bathed for at least 1 week) 2 Patient is unkcmpt (appears not to have bathed or changed clothes for several days) Patient Is clean but slovenly (uncombed hair, messy, ill-matched clothing. but clean) 3 Patient is clean and neatly groomed 4 Item 3. Expression of needs Patient docs not express needs (e.g.• hungry, need to go to the bathroom, cigarettc, etc.) 1 Patient exprcsses needs, but not in an organized fashion 2 Patient expresses needs in a simple and organized t:~hion 3 Patient expresses needs in an articulate and organized fashion 4 Item 4. Appointment compliance 1 Patient docs not keep appointments \vithout prompting 2 Patient is frequently late or misses appointments (> 50% of time) Patient is occasionally late for appointments (about 25% of time) 3 Patient is prompt and on time for appointments (> 90% of time) 4 Item 5. Socialization (interaction with people) 1 Patient docs not tolerate human interactions and isolates self Patient meets only \vith family members, 1-2 friends. or hospital staff 2 Patient interacts with family members, friends and acquaintances, and hospital staff 3 Patient interacts with family, friends, and acquaintances and meets nc\v people 4 Item 6. Socialization (exploring ne\v places) Patient docs not leave hislher o\vn room or house except \vith prompting from friends or staff 1 Patient leaves hislhcr o\vn room or house but only goes to a place (store/ restaurant) or activity (such as gym) that he/she kno\vs \vell 2 Patient leaves hislher o\vn room or house and goes to unfamiliar places to t~lke care of needed errands or can leave the ,vard and explore grounds 3 Patient goes spontaneously to nc\v places for social events as ,veil as tasks or errands 4 Item 7. Participation in goal-oriented activities Patient docs not participate in volunteer program. work program, day treatmcnt t or hospital 1 milieu program Patient participates in day treatment or hospital milieu program 2 Patient participates in day treatment and/or school. or a volunteer or \vork program at least 6 hoursAveek 3 Patient participates in school, volunteer ,vork, or ,yorks at least 20 hoursAveck 4 Item 8. Leisure time utilization Patient docs not organize or participate in leisure time activities (painting, reading. social groups. movics t etc.) 1 Patient participates in leisure time activities only if they are organized by someone else 2 Patient organizes and participates in at least one leisure time activity per ,vcek 3 Patient organizes and participates in at least three leisure time activities per ,vcck 4 Item 9. Financial management/independence Patient docs not handle his/her o\vn financial affairs in any manner 1 Patient budgets his/her own funds ,vith the help of a conservator/guardian 2 3 Patient budgets his/her own funds but frequently has problems Patient budgets hislhcr o\vn funds \vithout problems 4 Item 10. Short-term planning Patient docs not identify or formulate realistic short-term plans (realistically think about a place to livc t obtaining food) 1 Patient can identify but cannot formulate realistic short-tcnn plans 2 Patient can identify and realistically formulate short-term plans but needs assistance 3 in carrying them out Patient can identify and formulate short-tenn plans and can carry them out independently 4

220

VOLUME 4 • NUMBER 3 • SUMMER 1996

Rapaport et al. TABLE 1.

Scale of Functioning (SOF) (collti,,,,ed)

Item 11. Independence of living arrangements Patient cannot live independently or semi-independently and lives in a setting with 24-hour supervision, such as a lock-intensive inpatient \wrd, long-tenn residential treatment progrnm, or in seclusion Patient lives only with family members or a private custodian (requires close monitoring) or is currently hospitalized In a research or open ward Patient lives in a board-and-care or transitional living program Patient lives independently in an apartment or home \vith or without roommates Item 12. Insight/self.awareness Patient does not understand that he/she is psychiatrically ill Patient identifies symptoms of hislhcr own illness Patient identifies stressors that exacerbate his/ber own illness Patient identifies hislher own symptoms and stressors, and devises coping strategies to deal \vith stressors Item 13. Sleep regulation Patient does not organize hislher o\vn sleep patterns in any way and is up at all hours of the day and night Patient follows a reasonable sleep schedule only with the assistance of others and otherwise would wake-slccp at idiosyncratic times Patient follows a reasonable a sleep-\wke cycle but takes frequent daytime naps (at least 3 timcs/week, 1 hour/each) Patient follows a regular slecp-\vake pattern which he/she can control without the assistance of others Item 14. Thought processes (organization of information) Patient does not answer a simple question coherently and logically Patient answers a simple question but only with a yes/no response Patient answers a simple question logically and coherently with more than a yes/no

response

Patient ans\vers an open-ended question coherently and logically Item 15. Overall level of functioning Patient is severely impaired and cannot function without the assistance of a highly structured environment (Iong-tenn placement facility) Patient is moderately impaired, but can function with a great deal of structure and support from family or supportive institutions (lives in a highly structured program) Patient is fairly impaired, but can live and function fairly autonomously with some assistance from family) friends, or other agencies (i.e., lives in board-and-care, goes to therapy, sees friends) Patient can live independcndy, organize time and flnances, and has friends and a social life

with scales assessing negative symptoms, both indications of nomological validi~ Furthermore, we postulated that the SOF and the commonly used measures offunctioning that share some common features would be significantly intercorrelated, collectively representing one or more functional domains (an indication of trait validity).

METHODS All the 123 subjects in this study signed a written informed consent to participate in THE AMEIUCAN JOURNAL OF GEIUATIUC PSYCHIATRY

1 2 3 4 1

2 3

4 1

2

3 4 1 2

3

4

1 2 3 4

research. The 45 normal volunteers were recruited by word-of-mouth, byadvertisements in newsletters for senior citizens, and from non-affiliated personnel in the San Diego Veterans Mfairs (VA) Medical Center. The 78 outpatients with schizophrenia and schizoaffective disorder were recruited from the San Diego VA Medical Center, the University ofCalifornia SanDiego Medical Center, County Mental Health Services, and private physicians in the local community. All the subjects were over the age of 45 years, and a majority were Caucasian men. Structured neurological and medical histories were ab221

Scale ofFunctioning in Schizophrenia tained and a physical examination was performed on the subjects by qualified physicians. The Structured Clinical Interview for DSM-III-R (SeID) 19 was adlninistered by one of the board-certified or board-eligible geriatric psychiatry fellows to arrive at a diagnosis. The clinical data were presented at a diagnostic conference attended by at least two board-certified geriatric psychiatrists, who were involved in making the final diagnosis. The research staffofthe Clinical Research Center (eRe) on Late-Life Psychosis were trained to use the SOF by one of us (f8). This training occurred over a period of 4 weeks. The subjects were rated by four separate groups ofraters, who were unaware of the hypotheses being tested and the rating results ofth.e othergroups. The eRe Clinical Core raters were responsible for evaluating psychopathology with the BPRS, l the PANSS,2 the Scales for the Assessment of Positive and Negative Symptoms (SAPS and SANS, respectively),20,21 the Hamilton Rating Scale for Depression (Ham-D),22 and the SOFa The Neurology Core rater was responsible for administering the Mini-Mental State Examination (MMSE) ,23 the Pfeffer Outpatient Disability Scale, 10 and Lawton Powell's Physical Self-Maintenance Scale. 11 The Psychosocial Core rater was responsible for administering the QWB Scale? and the Social Adjustment Scale (SAS)6 modified by Cooper. 24 The Neuropsychology Core psychometrist gave the Dementia Rating Scale (DRS)25 and performed various other neuropsychological evaluations. The interrater reliability (intraclass correlation coefficient) was 0.76 or greater for all the scales cited above. For administrative reasons, fewer subjects had ratings on the DRS and Pfeffer Outpatient Disability Scale (total n = 52 and 87, respectively) than on other scales.

correlation coefficient (ICC) was calculated to estimate interrater reliability of the SOF. The demographic and clinical data were assessed for normality of distribution within groups, and homogeneity of variance between groups. When these assumptions were not met, data were transformed to meet these assumptions. Data analysis included the following: descriptive statistics (means, standard deviations [SD], percentages), and analysis of variance (ANOVA), and t-tests comparing the diagnostic groups. (Because an ANOVA demonstrated that schizophrenia and schizoaffective subjects did not differ significantly on any primary measures, data from these two diagnostic groups were combined for the final data analysis of the patient cohort.) Pearson correlation coefficients (1·) and t-tests were used to investigate the nomological validity of the SOFa Pearson correlation coefficients ·and principalcomponents analysis (peA) were used to investigate the trait validity of the SOFa A second peA also contributed to the assessment of nomological validit:}r. The peA was used to determine how many constructs there were in a set of functioning measures intended to represent a single domain or several domains. After the peA was done, varimax rotation was used to -suggest what these domains were and which measures were the best representative of those domains. If the number of constructs and scale makeup were found to be as theorized, trait validity in the group tested would be . supported. 18 Some of the authors (LAM and DVJ) have successfully used this strategy previously to investigate this aspect of construct validity of measures of psychopathology: 26

Statistical Analysis

RESULTS

Cronbach's alpha was computed to assess internal consistenC}', and intraclass

The overall Cronbach alpha for the SOF

222

using the total sample was 0.87. The ICC VOLUME 4 • NUMBER 3 • SUMMER 1996

Rapaport et al. different (P < 0.001) in SOF total score, and also differed in ratings of psychopathology and scores on the MMSE, DRS, Pfeffer Outpatient Disability Scale score, Lawton Powell's Physical Self-Maintenance Scale, the QWB, and the SAS" Table 3 shows the. correlations between the SOF Total and the ratings of psychopathology for the patient group. The SOF scores were inversely correlated with BPRS, PANSS, SAPS, SANS, and Ham-D scores, the largest association being with the SANS score" Table 4 shows the correlations between the SOF total and the

for the SOF in a subsample of 16 schizophrenia and schizoaffective subjects was 0.94. The schizophrenia patients were younger and had less education than the comparison subjects. Mean (± SD) age for the two groups was 58.6 ± 9.7 vs. 66.2 ± 11.2 years, respectively (P = 0.001); and mean level of education was 12.5 ± 2.9 years vs. 13.6 ± 2.0 years, respectively (P = 0,,017). Acomparison ofthe rating characteristics of the normal comparison subjects and schizophrenia outpatients is presented in Table 2. The two groups were TABLE 2.

Comparison of clinical ratings in Ronnal subjects and schizophrenia patients Nonnal Comparison Subjects

Brief l)sychiatric Rating Scale (BPRS) Positive and Negative Syndrome Scale (PANSS) Scale of the Assessment of Positive Symptoms (SAPS) Scale of the Assessment of Negative Symptoms (SANS) Hamilton Depression Rating Scale (Ham..D) Dementia Rating Scale (DRS) Mini..Mental State Exam (MMSE) Pfcffcr ·Outpatient Disability Scale Physical Self..Maintenance Sealen Quality orWell..Being (QWB) Social Adjustment Score (SAS) Scale of Functioning (SOF)

"

Patients With Schizophrenia

Mean ± SD

Mean ± SD

PS

76

31.2 ± 9.3 57.1 ± 15.3 5.9 ± 4.4

0.001 0.001 0.001

8.1 ± 3.9

0.001

± 8.7

0.001 0.002 0.001 0.001 0.034 0.001 0.001 0.001

"

45

21.9 ± 3.9 34.6 ± 5.0 1.4 ± 1..7

45

1.6 ± 2.1

76

45

2.9 ± 3.0

15

141.7 ± 1.9 28.7 ± 1.2 0.4 ± 1.4

77 37 77

45 44

45

38 44 44 44 45

6.1 ± 0.7 ± 1.9 ± 58.1 ±

0.3 0.1 0.2 2.4

77 75

49 76 72 75

78

9.9 133.4 26.3 3.2

± 9.2 ± 2.9

± 6.3 ± 0.6 ± 2.2 ± 48.8 ±

3.3 0.6 0.1 0.4 6.6

Note.· The values for each rating scale represent total scores on that scale. All measures except the Physical Self..Maintenance Scale used separate variance I-tests. aMann-Whitney U test.

TABLE 3.

Correlations of scores on the Scale of Functioning (SOF) widl scales measuring psychopathology

Psychopathology Scales Brief Psychiatric R.'lting Scale (BPRS)3 Positive and Negativc Syndrome Scale (PANSS) Scalc for the Assessment of Positive Symptoms (SAPS) Scale for the Assessment of Negative Symptoms (SANS) Hamilton Depression Rating Scale (Ham-D)

SOF -0.30

-0.46 -0.30 -0.60 -0.38

PS

77 75 76 76 77

0.009 0.001 0.008 0.001 0..001

atogarithmic transform ,vas used.

THE AMEIUCAN JOURNAL OF GEIUATIUC PSYCHIATRY

223

Scale ofFunctioning in Schizophrenia scores on some commonly used. scales measuring cognitive or functional ability in the patient group. The SOF score correlated positivelywith the MMSE, the DRS, and QWB scale scores, and inversely with the Pfeffer Outpatient Disability Scale and Lawton Powell's Physical Self-Maintenance Scale scores. A PCA of the five cognitive or functioning scales with sample sizes of at least 72 patients each revealed two unrotated factors with eigenvalues greater than I.O-the first, accounting for 37% of the variance; and the second, accounting for an additional 22% of the variance. As seen in Table 5, when these two unrotated factors were rotated, the first rotated factor was defined by the SOF, MMSE, and Physical Self-Maintenance Scale; the second rotated factor defined by the QWB scale and TABLE 4.

Social Adjustment Scale. When the Pfeffer scale was added and the peA was conducted on the six scales, the total sample size dropped from 69 to 45 patients, but a similar factor matrix emerged; namel~ two unrotated factors with eigenvalues greater than 1.0, with the Pfefferscale joining the SOF and MMSE to define the first rotated factor, and the QWB scale and SAS defining the second rotated factor. When the Pfeffer Scale was included, however, the Physical Self-Maintenance Scale loaded on both factors. When the psychopathology scales listed in Table 3 were added to the original set of five cognitive or functioning scales with sample sizes of at least 72 patients each, a PCArevealed two unrotated factors with eigenvalues greater than 1.0, the first one accounting for 42% of the variance,

Correlations of scores on the Scale of Functioning (SOF) witb existing measures of cognitive or functional ability

Functional Ability Scales

soF'

Mini..Mcntal State Exam (MMSE)3 Dementia Rating Scale (DRS)3 Pfeffer Outpatient Disability Scaleh Physical Self-Maintenance Scalch Quality orWell-Being (QWB)a Social Adjustment Scale (SAS)b

0.27 0.48

" 77 37

49

-0.53 -0.23

76 72

0.30 -0.17

75

ps. 0.017 0.003 0.001 0.045 0.010 0.134

aHigher scores on these scales indIcate better functioning or quality of well-being. bHighcr scores on these scales indicate worse functioning.

TABLE 5.

First two factors in the PCA factor matrix and their varimax-rotated factor matrix for cognitive or functioning scale scores subjected to the PCA (N = 69)

Scale Scale of Functioning (SOF)3 Mini..Mental State Exam (MMSEt1 Physical Self-Maintenance Scale Quality ofWell..Being (QWB)3 Social Adjustment Scale (SAS)b Eigenvalue

Extracted Factor Factor 1 Factor 2 0.66 0.58

-0.53

0.16

0.55 -0.45

-0.56

-0.43 0.64

1.84

1.12

0.70

Rotated Factor Factor 2

Factor 1 0.58 0.80

-0.69 0.22 0.04 1.50

-0.34 0.00 0.04 -0.80 0.85 1.47

PCA = principal-components analysis. aHigher scores on these scales indicate better functioning or quality of well-being. bHigher scores on these scales indicate worse functioning.

Note:

224

VOLUME 4 • NUMBER 3

• SUMMER 1996

Rapaport et al. and the second one accounting for 16% of the variance. As seen in Table 6, when the two factors were rotated, the first factor was defined by the QWB scale and SAS along with all the measures of psychopathology except the SANS, and the second factor was defined by the SOF, MMSE t Physical Self-Maintenance Scale, and SANS.

DISCUSSION Cronbach's alpha was high, indicating that the SOF has high internal consistency. The ICC between raters using the scale was also high, suggesting that the SOF is are.. liable scale that can be used in a similar fashion by different raters. As illustrated in Table 3, the SOF was inversely correlated with conventional measures of psychopathology, especially those of negative symptoms. These correlations indicated that psychopathology accounted for between 9% and 36% of the SOF variance, with the highest proportion being accounted for by the SANS. This latter finding suggests that the SOF has some nomological validity. We also found significant correlations between the SOF score and the DRS and Pfeffer Outpatient TABLE 6.

Scale

Disability Scale scores. Those two scales accounted for 23% and 28%, respectively, of the SOF variance. There were also significant correlations between the SOF score and the MMSE, Lawton Powell's Physical Self-Maintenance Scale, and QWB scale scores that accounted for between 5% and 28% variance of the SOF. These associations suggest that the SOF has some trait validity. The results of the two peAs indicate that there were at least two domains of functioning that corresponded to certain domains of psychopatholo~ Five scales of cognitive or functioning ability clustered into two sets: the SOF, MMSE, and Physical Self-Maintenance Scale on the one hand, and the QWB scale and SAS on the other. We thus have strong evidence of trait validity-that is, that there are at least one or two domains of functioning. With somewhat more limited sample sizes available, the Pfeffer Outpatient Disability Scale appeared to clusterwith the SOF and MMSE, and, to an extent, with the Physical Self-Maintenance Scale. When measures of psychopathology were included as markers t the measures of negative symptoms clustered with the SOF, MMSE, and Physical Self-Maintenance Scale, whereas the positive and

First two factors in the PCA factor matrix and their varimax-rotated factor matrix for cognitive. functioning. and psychopathology scale scores subjected to the PCA (N = 63) Extracted Factor Factor 2 Factor 1

Scale of Functioning (SOF) -0.44 Mini-Mental State Exam (MMSE) -0.15 Physical Self-Maintenance Scale 0.39 Scale for the Assessment of Negative Symptoms 0.54 (SANS) Brief Psychiatric It"lting Scale (BPRS) 0.87 Hamilton Depression Rating Scale (Ham-D) 0.77 Positive And Negative Syndrome Scale (PAN55) 0.92 Scale for the Assessment of Positive Symptoms 0.81 (SAPS) Quality orWell-Being (QWB) -0.63 Social Adjustment Scale (SAS) 0.61 Eigenvalue 4.24

THE AMERICAN JOURNAL OF GEIUATIUC PSYCHIATRY

Rotated Factor Factor 2 Factor 1

-0.49

-0.18 0.11 0.13 0.31

-0.69 -0.65 0.68 0.66

0.26 0.02 0.13 0.37

0.90 0.72 0.90 0.88

0.09 0.28 0.23 -0.03

-0.05 0.22 1.58

-0.60 0.64 3.85

-0.19 0.03 1.98

0.56 0.65 -0.58

225

Scale ofFunctioning in Schizophrenia depressive or overall measures of psychopathology clustered with the QWB scale and SASe This finding was consistent with the expectation that negative symptoms would relate to the SOFa We therefore, have a strong indication that different domains of functioning, including the domain represented by the SOF, are related to different aspects of psychopatholog}'. It remains to be seen what criterion validity (concurrent or predictive) there may be for these measures of functioning. Although any interpretation of the re.. suits of our factor analyses is likely to be speculative, the clustering ofthe SOF with the MMSE, the Lawton Powell Physical Self-Maintenance Scale, and the Pfeffer Outpatient Disability Scale on one factor and the SAS and the QWB scale on a second factor warrants. comment. This finding suggests that the SOF and the other scales commonly used to assess geriatric functioning (Lawton Powell Physical Self.. Maintenance Scale and Pfeffer Outpatient Disability Scale) may be evaluating a different set ofcharacteristics than those that are measured by the SAS, one of the scales commonly used to measure general quality of life in psychiatry; and the QWB, a well-validated general measure of quality of life. The SAS, for example, includes measures ofaffective states, such as anger, shame, and wor11', whereas the SOF, Lawton Powell Physical Self..Maintenance Scale, and Pfeffer Outpatient Disability Scale do not. It should also be pointed out that the time frame used for rating is somewhat different for the SOF (1 week) and the SAS (2 weeks). Differences in the thresholds ofsensitivity for the SOF, Lawton Powell Physical Self-Maintenance Scale, Pfeffer Outpatient Disability Scale, SAS, and QWB might account for some of the differences in loading as well. The SAS and Q\VB are more general measures ofsocial adjustment and well-being, respectivel~ and they have higher minimum (floor) thresholds and higher upper (ceiling) thresholds, respec226

tivel~ These scales may be less sensitive to the types of incremental differences that may be required to fully describe the functioning of older or more psychiatrically disabled patients. The Lawton Powell Physical Self-Maintenance Scale l l and the Pfeffer Outpatient Disability Scale lO are instruments developed to assess functioning in older and more impaired individu~ als. The SOF is a disorder-specific scale that is designed to be sensitive to the restrictions in functioning seen in a debilitating psychotic disorder-that is, schizophrenia. We believe that combining disorder-specific or age-specific scales with more general measures, such as the SAS and QWB, facilitates the development of a more complete assessment of functioning and quality of life. It is important to know about the functioning of the patients because that is truly the "bottom line" in terms of measuring the effectiveness of any interventions on the whole person. Measures of psychopathology alone do not allow us to assess the impact of our interventions on the functional abilities of the person as a whole. A combination of the measurements of functional impairment and psychopathology, taken together, gives a more complete picture of the success or failure of any intervention. Furthermore, it enhances our understanding of the patients. The·value of a combination of psychopathology assessments and functional assessments may be particularly important when one is attempting to evaluate the impact of other comorbid psychiatric or medical conditions on the individual patients. There are several limitations to this study that must be acknowledged. It would always be beneficial to have a Jarger sample size than the present one, al.. though a sample of 78 schizophrenia patients and 45 normal comparison subjects for a IS-item scale was sufficient to discriminate the two groups on the measures used. A second potential concern is that

VOLUME 4 • NUMBER 3 • SUMMER 1996

Rapaport et ale the older outpatients with schizophrenia evaluated in this study were only mildly ill (lbble 2). The fact that the SOF was nonetheless able to differentiate these mildly symptomatic schizophrenia patients from normal comparison subjects suggests that the scale is sensitive. Another potential concern relates to Type I errors because of the large number of comparisons and correlations. We should point out, however, that all the comparisons between the diagnostic groups, except the one on the Lawton Powell Pllysical Self-Maintenance Scale score, would still be significant with Bonfecconi corrections. The same is true for all the correlations of the SOF score with scores on clinical ratings of psychopathology and with the Pfeffer Outpatient Disability Scale and DRS totals. Similarl~ all the. factor loadings defining the rotated factors of both peAs would still be significant if a Bonferroni correction were applied to each peA. Our patient and comparison groups differed on age and education, although the fact that the normal subjects were older might have reduced the chances of finding a significant difference in the level of functioning from schizophrenia patients. Ours was a population comprised predominantly of Caucasian men. The generalizability of these results to other types of subject samples remains to be established. Finall~ we focused on trait validity and nomological validity in this study: Other aspects of validity that were not studied include content validity (con-

sensus as. to relevance or coverage of content of the measure and representativeness of the items) and concurrent and predictive criterion validity. In conclusion t we have demonstrated that the SOF, a IS-item rating scale developed to assess the level of functioning in inpatients and outpatients with schizophrenia, is reliable and valid for use with older schizophrenia outpatients. As pos.. tulated, we found inverse relationships between the SOF and measures of psychopatholog}', especially of negative symptoms. Furthermore, we demonstrated correlations between the SOF and some commonly used scales designed to assess activities of daily living in older populations as well as more general measures of quality of life, such as the QWB scale. These measures of functioning were observed to cluster into two sets ofvariables apparently representing two domains of functioning. Our data indicate that the SOF is a valid clinical tool for measuring certain aspects of functioning in older schizophrenia outpatients.

Portions of this study were presented at the 148th annual meeting of the American Psychiatric Association, Miami, PL, May 1995.

The authors thank the anonymous reviewers ofthispaperfor some excellent suggestions for improvement. This work was supported, inpart, by NIMH grants MH43693, MH45131, MH49671, and by the Department a/Veterans Affairs.

References 1. Overall JE, Gorham DR: The Brief Psychiatric Rating Scale. Psychol Rep 1962; 10:799-812 2. Kay SR, Fiszbein A, Opler LA: The positive and negative syndrome scale (PANSS) for schizophrenia. Schizophr Bull 1987; 13:2:261-276 3. Gur RE, Mozley PD, Resnick 8M, ct al.: Relations among clinical scales in schizophrenia. Am J Psychiatry 1991; 148:472-478 4.Stern RG, Kahn RS t Davidson M: Predictors of

THE AMERICAN JOURNAL OF GEIUATIUC PSYCHIATRY

response to neuroleptic treatment in schizophrenia. Psychiatr Clio North Am 1993; 16:313-338 5.Keefe RS) Harvey PD, Lenzenweger MF, et at: Empirical assessment of the factorial structure of clinical symptoms in schizophrenia: negative symptoms. Psychiatry Res 1992; 44:153-165 6. Weissman MM, Bothwell S: Assessment of social adjustment by patient self-report. Arch Gen PSy-

227

Scale ofFunctioning in Schizophrenia chiatry 1976; 33:1111-1115 7. ~1,plan RM., Anderson JP., Wu AW., et al: The Quality of Wen-Being scale: applications in AIDS, cystic fibrosis, and arthritis. Med Care 1989; 27:527-543 8. Strauss jS., Carpenter WI': Characteristic symptoms and outcome in schizophrenia. Arch Gen Psychiatry 1974; 30:429-434 9.lionigfeld G, Gillis RD, Klett Cl: NOSIE"3D: A treatment-sensitive ward behavior scale. Psychol Rep 1966; 19: 180-182 10. Pfeffer RI, Kurosaki TI. Harrah CH, et al: Measurement of functional activities in older adults in the community. J Gerontol1982; 37:323-329 11. Lawton MP. Brody EM: Assessment of older people: self-maintaining and instrumental activities of daily living. Gerontologist 1969; 9:179-186 12. Rosen), Sweet RA, Mulsant BH, et a[: The Delirium Rating Scale in a psychogeriatric inpatient setting. J Neuropsychiatry CUn Neurosci 1994; 6:30-35 13. Harvey PD, Davidson M, Powchik Pt et al: Assessment ofdementia in elderly schizophrenics \vith structured rating scales. 5chizophr Res 1992; 7:85-90 14. Kincaid MM, :Harvey PDt Parrella M, ct al: Validity and utility of the ADAS-L for measurment of cognitive and functional impairment in geriatric schizophrenic inpatients. J Neuropsychiatry Clin Neurosci 1995; 7:76-81 15. Arnold SE. Gur RE, Shapiro RM, et al: Prospective clinicopathologic studies of schizophrenia: accrual and assessment of patients. Am J Psychiatry 1995; 152:731-737 16. Rapaport MH, BazzettaJJ, Zisook S. ct al: Evaluation of functioning in schizophrenia: data regarding the validity of a new scale. Presented at

228

the 146th Annual Meeting of the American Psychiatric Association, San Francisco, CA, May 1993, pp 131-132 17. Rapaport MH, BazzettaJ, McAdams LA, ctal: The validation of the Scale of Functioning for schizophrenic subjects. Nc\v Research Abstracts, presented at the 148th Annual Meeting of the American Psychiatric Association, Miami. FL~ May 1995, PP 120-121 18. Messick S: Test validity and the ethics of assessment. Am Psychol 1980; 35:1012-1027 19. Spitzer RL, Williams JB, Gibbon M, et al: Structured Clinical Interivew for DSM-III-R (SeID). Washington, DC, American Psychiatric Press, 1987 20. Andreasen NC: The Scale for the Assessment of Positive Symptoms (SAPS). Iowa City. The University of Iowa, 1984 21.Andreascn NC: The Scale for the Assessment of Negative Symptoms (SANS). Iowa City., The University of Iowa, 1981 22. Hamilton M: Development of a rating scale for primary depressive illness. Br J Soc Clio Psychol 1967; 6:278-296 23. Folstein MF, Folstein SE, McHugh PR: Mini-Mental State: a practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975; 12:189-198 24. Cooper P., Osborn M, Gath D, ct al: Evaluation of a modified self.report measure of social adjustment. Br J Psychiatry 1982; 141:68-75 25.Mattis S: Dementia Rating Scale. Odessa, FL. Psychological Assessment Resources, Inc., 1973 26. McAdams LA, Harris MJ, Bailey At et al: Validating specific psychopathology scales in older schizophrenic outpatients. J Nerv Ment Dis 1995; 184:246-251

VOLUME 4 • NUMBER 3 • SUMMER 1996