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The Pediatric Anxiety Rating Scale (PARS): Development and Psychometric Properties
The Pediatric Anxiety Rating Scale (PARS): Development and Psychometric Properties THE RESEARCH UNITS ON PEDIATRIC PSYCHOPHARMACOLOGY ANXIETY STUDY GROUP ABSTRACT Objective: To describe the development and psychometric properties of the Pediatric Anxiety Rating Scale (PARS), a clinician-rated instrument for assessing the severity of anxiety symptoms associated with common DSM-IV anxiety disorders (social phobia, separation anxiety disorder, and generalized anxiety disorder) in children. Method: As part of a multisite study of the efficacy of fluvoxamine, 128 children (aged 6–17) and their parents were interviewed weekly with the PARS. Data from multiple raters on a subsample of children (using live and videotaped interviews) were used to evaluate interrater reliability. Internal consistency, test-retest reliability, and validity (convergent, divergent) also were evaluated. Results: The PARS showed high interrater reliability, adequate test-retest reliability, and fair internal consistency. Convergent and divergent validity were satisfactory. PARS scores were sensitive to treatment and paralleled change in other measures of anxiety symptoms and global improvement. Conclusions: The PARS is a useful clinician-rated instrument for assessing pediatric anxiety symptoms, severity, and impairment, particularly in treatment studies. Further study of the psychometric properties is warranted. J. Am. Acad. Child Adolesc. Psychiatry, 2002, 41(9):1061–1069. Key Words: anxiety, children, adolescents, rating scales, assessment.
Anxiety disorders represent the most prevalent childhood psychiatric disorders, with estimates of point prevalence generally falling in the 3% to 13% range, depending on the degree of associated impairment (see Costello and Angold, 1995, for review). These disorders can severely impair the social, academic, familial, and personal functioning of affected children and negatively impact their families (e.g., Beidel et al., 1991; Francis et al., 1992; Strauss et al., 1988). In addition, existing longitudinal data, coupled with adults’ retrospective reports, suggest some continuity between child and adult disorders (Abe, 1972; Costello and Angold, 1995; Pine et al., 1998). In Accepted April 10, 2002. The study sites and authors are listed at the end of the text. The PARS and instructions for its administration are available via the Article Plus feature on the Journal’s Web site: www.jaacap.com. Supported by contracts from the NIMH to Johns Hopkins University (N01MH60016; PI: Dr. Riddle) and the Research Foundation for Mental Hygiene (N01MH60005; PI: Dr. Greenhill) and Solvay Pharmaceuticals; NIMH grants MH57503 and MH-01391 (Dr. Pine); NIMH RUPP contract N01MH70010 (Dr. McCracken); and National Center for Research Resources/NIH General Clinical Research Center grant M01 RR00052 (Johns Hopkins University School of Medicine). Reprint requests to Dr. Riddle, Division of Child and Adolescent Psychiatry, Johns Hopkins Children’s Center, Room 346, 600 North Wolfe Street, Baltimore, MD 21287-3325; e-mail: [email protected]. 0890-8567/02/4109–1061䉷2002 by the American Academy of Child and Adolescent Psychiatry. DOI: 10.1097/01.CHI.0000020259.43550.F4
light of the high prevalence of these disorders and the associated short- and long-term impairment, there is a critical need for developing reliable and valid methods for measuring and monitoring the severity of these disorders and their symptoms. The primary objective in developing the Pediatric Anxiety Rating Scale (PARS) was to address this need, particularly for clinician-rated assessments in treatment studies. Currently, the most common methods for identifying and measuring anxiety in youths are structured and semistructured diagnostic interviews, self-report rating scales, and clinician-rated instruments. Each of these methods is useful for specific purposes. For instance, structured diagnostic interviews, such as the Diagnostic Interview Schedule for Children (Shaffer et al., 2000), were primarily developed for use in epidemiological research to make diagnoses and are most useful for reliably ascertaining “externalizing” diagnoses, e.g., conduct disorder. Semistructured interviews, such as the Anxiety Disorders Interview Schedule for Children (ADIS-C) (Silverman and Albano, 1996), the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) (Ambrosini, 2000), and the Diagnostic Interview for Children and Adolescents (Welner et al., 1987), are used predominantly in clinical research and are particularly useful for making diagnoses. These instruments also facil-
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itate the gathering of information on a broad range of symptoms, impairment associated with specific diagnoses, duration of illness, and lifetime occurrences of illness. Newer versions of these instruments, e.g., the ADIS-C, assess severity of individual anxiety disorders and have been used as an outcome measure in treatment studies (Kendall et al., 1997; Silverman et. al., 1999). Self-report rating scales are most useful for screening and assessing the degree to which a child’s anxiety is normative in the context of developmental, gender, and cultural factors. In addition, these rating scales are useful for monitoring changes in anxiety symptoms over time or in relation to specific treatments. Examples of anxiety scales that assess a broad range of symptoms include the Revised Children’s Manifest Anxiety Scale (Reynolds and Richmond, 1978), the Multidimensional Anxiety Scale for Children (MASC) (March et al., 1997), and the Screen for Child Anxiety Related Emotional Disorders (SCARED) (Birmaher et al., 1997). Despite their advantages, self-report rating scales are dependent on the child’s cognitive abilities (i.e., to read and comprehend items), do not directly assess impairment, and are vulnerable to response biases inherent in self-report measures (Anastasi and Urbina, 1997). In contrast to parent reports or child-completed selfreports of anxiety, few clinician-rated instruments exist for assessing the severity of symptoms of pediatric anxiety disorders. Among the available instruments are the Hamilton Anxiety Rating Scale (HAM-A) (Hamilton, 1959) and the Children’s Yale-Brown Obsessive Compulsive Scale (CY-BOCS) (Scahill et al., 1997). The HAM-A assesses a broad range of anxiety symptoms; however, they are predominantly physiological or somatic in nature. More important, this measure was originally developed for use with adults; the psychometric properties have been examined in adolescents (Clark and Donovan, 1994), but it is unclear to what extent it accurately reflects current concepts regarding anxiety in pediatric samples. Although semistructured and structured diagnostic interviews, such as the ADIS-C, are clinician-administered and may assess severity of individual anxiety symptoms or disorders, these instruments typically do not provide an index of anxiety severity across disorders. Rather, these instruments link severity to one specific symptom or disorder (e.g., social phobia) based on the current (or a past) version of the DSM. Changes in DSM criteria for childhood anxiety disorders, the overlap of symptoms among anxiety disorders, and the high rates of comorbidity among anxiety disorders in youths (see Curry and Murphy, 1995, 1062
for review) highlight the limitation of this method for assessing the overall severity of anxiety symptoms. This issue is particularly relevant with respect to assessing global changes in anxiety severity in the context of treatment outcome studies that include children with more than one anxiety disorder (Greenhill et al., 1998). In summary, there are several methods for assessing anxiety symptoms in youths, each useful for specific purposes. However, to date there are no clinician-rated instruments for assessing both impairment and overall anxiety severity that cover the important domains of anxiety in youths. To fill this gap, the development of a new instrument was undertaken. The PARS was designed to assess the frequency, severity, and associated impairment of separation anxiety, social phobia, and generalized anxiety symptoms in youths aged 6–17 years. The purpose of the present study is to describe this instrument and present initial data on its psychometric properties. METHOD Construction and Description of the PARS The PARS and instructions for its administration are available via the Article Plus feature on the Journal’s Web site (www.jaacap.com). It was modeled after the CY-BOCS and the Yale Global Tic Severity Scale (YGTSS) (Leckman et al., 1989). Item content was derived as follows. First, items were generated predominantly from the DSMIV criteria for anxiety disorders including social phobia (SoP), separation anxiety disorder (SAD), and generalized anxiety disorder (GAD). Second, items were circulated among a group of expert child and adolescent psychiatrists and psychologists at the participating sites of the Research Units on Pediatric Psychopharmacology (RUPP) who were asked to comment on (1) face validity; (2) comprehensiveness; (3) overlap with other constructs, for example, disruptive behavior or depression; and (4) readability and clarity. After several iterations of this process, a 50-item “final version” was adopted for use in the RUPP fluvoxamine anxiety trial. This 50-item symptom checklist grouped items into the following categories: Social Interactions or Performance Situations (9 items), Separation (10 items), Generalized (8 items), Specific Phobia (4 items), Physical Signs and Symptoms (13 items), and Other (6 items). Each symptom is scored by the interviewing clinician as present or absent (yes/no) during the previous week. Information about symptoms is gathered from interviews with both the child and parent(s). These interviews may be conducted with child and parent together, as was done in the present study, or separately. Endorsed symptoms are then collectively (i.e., integrating both child and parent information) rated by the clinician on seven dimensions of severity, using a 6-point scale (0 for none, and 1–5 for minimal to extreme) for each dimension. These dimensions are (1) number of symptoms (none to more than 10), (2) frequency (none to several hours per day), (3) severity of distress associated with anxiety symptoms (none to extreme), (4) severity of physical symptoms (none to extreme), (5) avoidance (none to extreme), (6) interference at home (no interference to totally or almost totally unable to function at home), and (7) interference out of home (no interference to totally or almost totally unable to function out of home such as with peers
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or at school). A score of 3 on each of these 5-point scales indicates a clinically significant level of severity, avoidance, or interference. A PARS Total Score was calculated by summing five of the seven items. The “Number of Symptoms” item and the “Physical Symptoms” item were excluded. The “Number of Symptoms” item was excluded because of concern that it might not be related to severity of anxiety and might be highly skewed in this sample. The “Physical Symptoms” item was excluded because of concern that outcome data included ratings on subjects who were being treated with a selective serotonin reuptake inhibitor (SSRI). Common adverse events of SSRIs include symptoms that are identical with some of the symptoms in the PARS Symptom Checklist: “sweating”; “feels sick to stomach, nausea or abdominal distress”; “restlessness or feeling keyed-up or on edge”; “sleep disturbance, especially difficulty falling asleep.” Thus, throughout this article, PARS Total Score refers to a sum of the remaining five items. Participants The current study was conducted in two stages. The first stage examined the interrater reliability of the PARS, while the second stage examined test-retest reliability and validity. To examine interrater reliability, 16 children aged 5–15 years (63% males; mean age 10.5 years) were interviewed with the PARS. Of these children, 11 were white, 1 was African American, 2 were Hispanic American, and 2 were Asian American. Seven of these children also participated in the RUPP anxiety treatment study (described below). The second stage of this study was conducted within the context of a double-blind, placebo-controlled clinical trial of fluvoxamine for youths with SoP, SAD, and GAD (RUPP, 2001). Five RUPP sites were involved in that study: Duke University, Johns Hopkins University, New York State Psychiatric Institute/Columbia University, New York University, and University of California, Los Angeles. Participants included 128 children, aged 6–17 years (mean = 10.8 years; 49% female; 63% white), with a current DSM-IV diagnosis of SoP, SAD, or GAD, based on child and parent K-SADS interview with a trained clinician. Sites recruited participants from a variety of sources, including mental health settings and newspaper advertisements. Other inclusion criteria were as follows: clinically significant impairment as assessed with a Children’s Global Assessment Scale (CGAS) score less than 60; and availability of both a parent and the child for weekly visits. Exclusion criteria included current use of any illicit or prescribed psychoactive substance; current diagnoses of either major depressive disorder, Tourette’s disorder, obsessive-compulsive disorder, posttraumatic stress disorder, conduct disorder, or panic disorder; any past or current history of mania, psychosis, or pervasive developmental disorder; current suicidal ideation; mental retardation as assessed with the Kaufman Brief Intelligence Test (IQ < 70); previous use of an SSRI in appropriate doses; and a diagnosis of attention-deficit/hyperactivity disorder that required pharmacological treatment. Table 1 summarizes the characteristics of participants in the entire sample. Measures Schedule for Affective Disorders and Schizophrenia for School-Age Children. Inclusion/exclusion criteria for psychiatric diagnoses were assessed with the K-SADS (Ambrosini, 2000; Kaufman et al., 1997), administered by experienced clinicians. The K-SADS possesses good reliability and validity (Ambrosini, 2000). The entire K-SADS interview was administered during intake into the treatment study. Children’s Global Assessment Scale. The CGAS (Bird et al., 1987; Shaffer et al., 1983) is a modification of the adult GAS and provides a measure of global impairment and functioning over the previous month. The
TABLE 1 Sociodemographic and Clinical Characteristics of Entire Sample (N = 128) Mean age (years) Gender (female) Ethnicity White Hispanic African American (non-Hispanic) Other Total family income <$25,000 $25,000–39,999 $40,000–59,000 >$60,000 Refused/unknown Diagnosis (based on K-SADS) SoP only SAD only GAD only SoP and SAD only SoP and GAD only SAD and GAD only SoP, SAD, and GAD
10.8 63 (49.2) 81 (63.3) 24 (18.8) 9 (7.0) 14 (10.9) 19 (14.8) 20 (15.6) 18 (14.1) 55 (43.0) 16 (12.5) 26 (20.3) 18 (14.1) 5 (3.9) 11 (8.6) 21 (16.4) 21 (16.4) 26 (20.3)
Note: With the exception of age, values represent n (%). K-SADS = Schedule for Affective Disorders and Schizophrenia for School-Age Children; SoP = social phobia; SAD = separation anxiety disorder; GAD = generalized anxiety disorder. scale ranges from 1 (lowest) to 100 (highest). Ample evidence exists supporting the psychometric soundness of the scale (Green et al., 1994). Clinician’s Global Impression of Severity Scale. The Clinician’s Global Impression of Severity Scale (CGI-S) (Guy, 1976) was used to assess global severity of anxiety using a 7-point scale, ranging from normal to most extreme. This measure was completed at major assessment points by a clinician to assess changes in anxiety severity. Clinician’s Global Impression of Improvement Scale. The Clinician’s Global Impression of Improvement Scale (CGI-I) was used to assess overall global change at each visit using data from all other measures in the study. An 8-point scale (Abikoff and Gittelman, 1985; Klein et al., 1992) that is similar to the traditional 7-item scale (Guy, 1976), but allows for greater discrimination among levels of response in treatment responders, was used (1 = completely well, recovered; 2 = much improved; 3 = improved; 4 = slightly improved; 5 = unchanged; 6 = slightly worse; 7 = worse; 8 = much worse). Multidimensional Anxiety Scale for Children. The MASC (March et al., 1997) is a 39-item, 4-point, Likert, self-report rating scale that has shown robust psychometric properties in studies of clinical and nonclinical samples. The MASC includes four factors derived to match the population factor structure of anxiety: physical symptoms (tense/ restless and somatic/autonomic subfactors), social anxiety (humiliation/ rejection and public performance subfactors), harm avoidance (anxious coping and perfectionism subfactors), and separation/panic anxiety. Three-week test-retest reliability for the MASC is good as shown by intraclass correlation coefficient (ICC) = 0.79 in clinical (March et al., 1997) and 0.88 in school-based samples (March and Sullivan, 1999). Screen for Child Anxiety Related Emotional Disorders. The SCARED (Birmaher et al., 1997, 1999) is a 41-item, child- and parent-report instrument that assesses DSM-IV symptoms of panic, SAD, SoP, and GAD and symptoms of school refusal. The SCARED has shown good
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psychometric properties in two different large clinical samples (Birmaher et al., 1997, 1999) and in a community sample (Muris et al., 1998, 1999). For instance, data obtained on an outpatient clinic sample of 341 youths (9–18 years, mean = 14.5) indicated test-retest reliability coefficients ranging from 0.70 to 0.90 (over a 4-day to 15week period) and internal consistency coefficients of the subscales ranged from 0.74 to 0.89 (Birmaher et al., 1997). The SCARED demonstrated good sensitivity and specificity in a study of children with anxiety, depressive, and disruptive disorders, and it was sensitive to treatment effects (Birmaher et al., 1999). Children’s Depression Rating Scale. The Children’s Depression Rating Scale (CDRS) (Poznanski et al., 1984) is a clinician-administered screening tool that assesses 17 symptom areas of depression (e.g., sleep, social withdrawal, school). The CDRS is widely used and has established psychometric properties. For instance, test-retest reliability over a 2-week period was 0.86, interrater reliability was 0.92 (for the summary score), and the Cronbach α was .85. Moreover, the CDRS discriminates between depressed and nondepressed psychiatric patients and is correlated with other measures of depression and suicidal behavior (Poznanski et al., 1984). Hamilton Anxiety Rating Scale. The HAM-A (Hamilton, 1959) is a 14-item, clinician-administered measure of anxiety symptoms with a focus on somatic symptoms. The measure has demonstrated reliability and construct validity with adults and adolescents. Specifically, in a sample of adolescents, interrater reliability was 0.92 and the Cronbach α was .86 (Clark and Donovan, 1994). The HAM-A was also correlated with self-report measures of anxiety and fear and discriminated between nonclinical, clinical, and clinically anxious youths. Child Behavior Checklist. The Child Behavior Checklist (CBCL) (Achenbach, 1991), a widely used parent-completed measure, assesses a broad range of child behavior problems. The measure yields a Total Problem Behavior score, two broad-band scores (Internalizing and Externalizing), and several narrow-band scale scores (e.g., Anxious/ Depressed, Inattention, etc.). Procedure Prior to participation in this study, all parents signed informed consents; children over age 6 signed assents. A comprehensive pretreatment evaluation was conducted which included the diagnostic interview and additional measures to assess inclusion/exclusion criteria and outcome measures. The pretreatment evaluation was completed over three visits, which spanned a 3- to 4-week period of time. Generally, at the first visit the K-SADS, PARS, CGI, CGAS, and HAM-A were administered. On the second visit, parents completed the CBCL and medical assessments were conducted (e.g., medical history, physical examination, blood draw). On the third visit, demographics, family history, and intellectual assessments were conducted. At baseline, the CDRS, K-SADS, PARS, HAM-A, CGI, CGAS, SCARED, MASC, other self-report and medical procedures were completed. Thus, prior to treatment, the PARS was administered on two separate occasions by the same pediatric psychiatrist or psychologist: at the screening evaluation (the beginning of the 3-week period) and at the baseline (randomization) evaluation (the end of the 3- to 4-week period). At each visit, the PARS was conducted prior to all other rating scales. For the interrater reliability part of the study, live interviews were conducted and videotaped. Clinicians who were present during the interview provided ratings. All other ratings were from clinicians who watched the videotaped session. During the interviews, children were administered the PARS first, then parents. Parents and children were brought together to sort out significant discrepancies. There were a total of 11 raters from the 5 sites, 9 child and adolescent psychiatrists
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and 2 clinical child psychologists (this group of raters participated in a training session on the use of the PARS and completed all assessments described above); however, 5 of the 11 raters were unable to rate all subjects. Of these five, two raters were available for seven videotaped interviews only; one rater was available for the seven videotaped interviews and two live interviews; and one rater was available for seven videotaped interviews and six live interviews. During the treatment phase, the treating child and adolescent psychiatrist, who was blind to treatment condition, saw each child and a parent on a weekly basis for the first 6 weeks of the trial and again at week 8. At each visit, psychiatrists completed three tasks: (1) they administered the supportive psychoeducational therapy to children and families, (2) they conducted a clinical assessment of anxiety symptoms using the PARS and other instruments, and (3) they assessed adverse events. The rating scales described above were also completed at week 4 and week 8 treatment visits. Primary Statistical Analyses Reliability. Internal consistency was calculated using the Cronbach α for the five items (see below) that comprise the PARS Total Score. ICCs (Shrout and Fleiss, 1979) were calculated for the Total Score and individual severity items to assess interrater and test-retest reliability, which was examined over the 1- to 4-week period between screening and baseline. Validity. Convergent validity was evaluated by calculating Pearson correlation coefficients for the PARS with other anxiety measures including the MASC, SCARED, HAM-A, and CBCL (i.e., Anxious/Depressed and total Internalizing scores). To examine divergent validity, we examined the correlation between the PARS Total Score and scores on the CDRS and the CBCL Externalizing and Inattention subscale scores. Statistically significant and relatively large correlations were expected for convergent, but not divergent, validity. Differences between dependent correlations were tested using the method described by Cohen and Cohen (1975). To assess the PARS sensitivity to change, we examined the correspondence of changes in PARS scores to changes in the CGII, CGI-S, CGAS, and other measures of anxiety before and after the 8week, double-blind, placebo-controlled study of fluvoxamine. All children were included in each analysis as long as the data were not missing. Systematic missing data were not a problem, although missing data were evident for most measures. Statistical significance is reported at the 5% level.
RESULTS Internal Validity
Descriptive Statistics. The means and standard deviations of the PARS scores for the seven individual severity items and the five-item Total Score for boys, girls, and the total sample are presented in Table 2. In general, the means (and modes) for the PARS individual items were above the mid-point (2.5) and slightly positively skewed on the 6-point (0–5) scale. The PARS Total Score was unimodal and normally distributed. A comparison of PARS Total Scores between younger and older children using the total sample showed no significant differences. The t test comparisons between boys and girls on the PARS Total revealed
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TABLE 2 Mean Scores (and Standard Deviations) on the PARS at Baseline Boys (n = 64)
PARS Item Number of Symptoms Symptom Frequency Severity-Distress Severity-Somatic Avoidance Interference-Home Interference-Other Total (5-item)a
4.8 3.9 4.0 2.8 3.8 3.4 3.4 18.5
(0.6) (1.0) (0.8) (1.2) (1.0) (1.2) (1.2) (3.5)
Girls (n = 63) 4.8 3.9 4.0 2.6 4.0 3.4 3.1 18.8
Total (n = 127)
(0.5) (1.0) (0.7) (1.5) (0.8) (1.0) (1.1) (3.0)
4.8 3.9 4.0 2.7 3.9 3.4 3.5 18.7
(0.6) (1.0) (0.7) (1.4) (0.9) (1.1) (1.2) (3.21)
Note: Items range from 0 (none) to 5 (extreme); Total Score range is 0 to 25. PARS = Pediatric Anxiety Rating Scale. a Two items, Number of Symptoms and Physical Symptoms, were excluded from five-item Total.
no significant differences—both for the total sample and within younger (ages 6–12) or older (ages 13–17) age groups. No differences were found on any PARS items between whites and Hispanics (the largest minority group in the sample). The correlation between PARS Total Scores and income was nonsignificant (r = –0.15). Internal Consistency. The Cronbach α coefficient for the five items comprising the PARS Total Score at baseline was .64, indicating that the PARS items are associated but not redundant. Correlations among the PARS seven items and the PARS five-item Total Score severity items at baseline are presented in Table 3. Correlation coefficients among the seven severity items ranged from 0.08 (between total number of symptoms and interference out of home) and 0.45 (between interference at home and distress). Most of the seven individual severity items were moderately correlated with the PARS Total Score (range, 0.24–0.68). Correlations among the individual PARS severity items were quite varied, ranging
from 0.08 (Interference-Home and Interference-Other) and 0.50 (Avoidance and Interference-Other). Reliability
Interrater Reliability. The ICC for the PARS Total Score across raters was 0.97. Table 4 displays the ICCs for each of the seven severity items. Test-Retest Reliability. The test-retest reliability coefficient between screen and baseline (mean = 24.7 ± 14.7 days) for the PARS Total Score was 0.55 for the total sample. ICCs for each item ranged from 0.35 (Avoidance) to 0.59 (Interference-Home). These coefficients are presented in Table 5. Validity: Convergent and Divergent
To assess convergent validity, we calculated Pearson correlations between the PARS Total Score at baseline and other measures of anxiety, including (1) CGI-S, (2) HAM-A, (3) MASC, (4) SCARED-child and -parent versions, and (5) CBCL Anxious/Depressed subscale and Internalizing subscales. These results are presented in Table 6. The PARS Total score was moderately correlated with the other clinician- and parent-rated measures of anxiety, such as the CGI-S (clinician rating of anxiety severity), HAM-A, and SCARED-P. Correlations were generally weakest with the two child self-report measures of anxiety (MASC and SCARED-C). In additional analyses, each PARS severity item was correlated with the above measures (correlations available from the authors). Using a minimum criterion of r = 0.40, results indicated that the CGI-S was correlated with PARS Distress (0.41) and Interference-Out of Home (0.55), and the HAM-A was correlated with Interference-Home (0.55), Physical Symptoms (0.46), and Distress (0.43). No other correlations surpassed this criterion.
TABLE 3 Correlations Among PARS Seven Items and PARS Five-Item Total Score at Baseline 1 1. 2. 3. 4. 5. 6. 7. 8.
Number of Symptoms Frequency Distress Physical Symptoms Avoidance Interference-Home Interference-Other Total Score
1
2 0.34*** 1
3 0.41*** 0.37*** 1
4 0.18* 0.13 0.32*** 1
5
6
7
8
0.20* 0.13 0.18* 0.06 1
0.36*** 0.39*** 0.45*** 0.14 0.19* 1
0.08 0.15 0.34*** 0.19* 0.50*** 0.08 1
0.41*** 0.63*** 0.68*** 0.24* 0.62*** 0.65*** 0.66*** 1
Note: PARS = Pediatric Anxiety Rating Scale. * p < .05; *** p < .001.
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TABLE 5 ICC Test-Retest Coefficients and Means at Screen and Baseline on the PARS
TABLE 4 ICC Interrater Reliability Coefficients on the PARS PARS
ICC a
Number of Symptoms Frequency Distress Physical Symptoms Avoidance Interference-Home Interference-Other Total (5-item)
0.78 0.92 0.96 0.89 0.92 0.89 0.92 0.97
Note: PARS = Pediatric Anxiety Rating Scale; ICC = intraclass correlation coefficient. a All ICC values significant at p < .001.
Divergent validity was assessed in a preliminary manner by correlating the PARS Total Score at baseline with the baseline CDRS and the CBCL Inattention and Externalizing subscales. These correlations, which appear in Table 6, were relatively small (0.18–0.30). A test of the difference in correlations between the PARS Total Score and the CBCL Internalizing (0.40) and CBCL Externalizing (0.22) scales revealed that the correlation between the PARS and the CBCL Internalizing scale was significantly larger (t119 = 2.23, p = .03). Sensitivity to Treatment. We also examined correlations between change in the PARS Total Score and change after treatment in (1) global assessment of functioning (CGAS), (2) clinician-rated global anxiety severity (CGI-S), (3)
PARS
ICC a
Screen (SD)
Number of Symptoms Frequency Distress Physical Symptoms Avoidance Interference-Home Interference-Other Total Score (5-item)
0.48 0.42 0.37 0.45 0.35 0.59 0.54 0.55
4.6 3.7 3.8 2.8 3.7 3.4 3.3 18.0
Baseline (SD)
(0.8) (1.1) (0.6) (1.3) (0.9) (1.0) (1.2) (3.1)
4.8 3.9 4.0 2.7 3.9 3.4 3.5 18.7
(0.6) (1.0) (0.7) (1.4) (0.9) (1.1) (1.2) (3.21)
Note: PARS = Pediatric Anxiety Rating Scale; ICC = intraclass correlation coefficient. a All ICC values significant at p < .001.
clinician-rated anxiety scale (HAM-A), and (4) self-reports and parent reports of anxiety (i.e., MASC, SCARED-C, and SCARED-P). Change in the PARS Total Score was significantly correlated with pre-post treatment changes in the CGAS (0.78), CGI-S (0.53), and HAM-A (0.41), but uncorrelated with changes in the MASC (0.03), SCARED-C (0.02), or SCARED-P (0.03). DISCUSSION
The purpose of this study was to describe the development and initial psychometric properties of the PARS, a clinician-rated instrument for assessing the severity of symptoms common to a broad range of pediatric anxiety disorders. The PARS was designed to fill a gap among
TABLE 6 Correlations Between PARS Total Score and Measures of Internalizing and Externalizing Behaviors at Baseline Scale Convergent validity CGI-S HAM-A SCARED-P CBCL-I CBCL-A SCARED-C MASC Divergent validity CDRS-P CBCL-In CBCL-E CDRS-C
Construct
Source
Mean
(SD)
R
Anxiety Anxiety Anxiety Internalizing Anxiety Anxiety Anxiety
Clinician Clinician Parent Parent Parent Child Child
5.06 17.25 36.60 20.36 11.30 31.52 54.27
(0.81) (7.67) (13.38) (9.77) (5.48) (13.79) (18.58)
0.61*** 0.49*** 0.46*** 0.41*** 0.36*** 0.32*** 0.22*
Depression Inattention Externalizing Depression
Clinician Parent Parent Clinician
30.44 6.93 13.16 28.49
(10.52) (4.60) (9.68) (9.16)
0.33*** 0.27** 0.22* 0.18*
Note: CGI-S = Clinician’s Global Impression of Severity Scale; HAM-A = Hamilton Anxiety Rating Scale; SCARED-P = Screen for Child Anxiety Rated Emotional Disorders-Parent; CBCL-I = Child Behavior Checklist-Internalizing; CBCL-A = Child Behavior Checklist-Anxiety; SCARED-C = Screen for Anxiety Related Emotional Disorders-Child; MASC = Multidimensional Anxiety Scale for Children; CDRS-P = Children’s Depression Rating Scale-Parent; CBCL-In = Child Behavior Checklist-Inattention; CBCL-E = Child Behavior Checklist-Externalizing; CDRS-C = Children’s Depression Rating Scale-Child. * p < .05; ** p < .01; *** p < .001.
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existing child anxiety assessment tools, and our findings suggest it holds considerable promise as both a research and clinical instrument. Descriptive Statistics and Selection of Severity Items
Modeled after the CY-BOCS and YGTSS, the current version of the PARS has 50 symptom items and 7 severity/ impairment items. A total score was obtained by summing five of the severity items. For reasons presented in the “Method” section, two items, “Number of Symptoms” and “Severity of Physical Symptoms,” were not included in the calculation of the total score. Although the distribution of the PARS Total Score was “normal,” most of the individual severity items were positively skewed. For instance, the modal score for the “Number of Symptoms” item was 5.0, indicating that most youths with SoP, SAD, and/or GAD in the present sample had greater than 10 symptoms. Consequently, this item should be dropped from the PARS or new anchors need to be established and this item then needs to be reevaluated. The “Severity of Physical Symptoms” item was dropped from the total score because many of the physical symptoms of anxiety are similar to adverse events of psychotropic medications, particularly the SSRIs (e.g., “trembling and shaking,” “sweating,” “feels sick to stomach, nausea or abdominal distress”). Obviously, for assessment of anxiety in children not receiving medication, this would not be an issue. Thus further work is needed to clarify the value of including physical symptoms in the PARS Total Score. Comparisons between boys and girls and younger and older children on the PARS Total Score revealed no significant differences. The absence of gender and age differences may reflect the nature of the present sample. Both boys and girls in this study met strict inclusion/exclusion criteria and thus were selected to surpass a prespecified level of severity of anxiety. Correlations among the PARS severity items and PARS Total Score varied, ranging from 0.08 (between total number of symptoms and interference out of home) to 0.45 (between interference at home and anxiety severity). The five individual severity items that comprise the Total Score were uniformly correlated with the PARS Total Score (range, 0.62–0.68). Of note, the two omitted items, “Number of Symptoms” and “Severity of Physical Symptoms,” showed the lowest correlation with the PARS Total Score, suggesting that they may be a poor proxy of overall severity or impairment. The low correlations for these two items support the decision to omit them in cal-
culating the PARS Total Score. Alternatively, because the PARS Total Score contains the other five items, it is possible that the other five correlations are artificially elevated. As noted earlier, correlations among the individual PARS severity items were quite varied, ranging from 0.08 (Interference-Home and Interference-Other) and 0.50 (Avoidance and Interference-Other). The pattern of correlations suggests that children who report a high number of symptoms are more likely to experience them more often and report more distress and interference at home. In addition, avoidance due to anxiety was most closely linked to higher levels of distress and interference outside of the home (e.g., with friends, at school). Finally, the absence of a relation between the two interference items suggests that children’s impairment may be domain-specific. Reliability
In general, the PARS demonstrated acceptable psychometric properties with respect to interrater reliability (high, ICC = 0.97), internal consistency (adequate, α = .64), and test-retest reliability (fair, ICC = 0.55). Regarding test-retest reliability, to some extent these lower coefficients reflect expected instability of anxiety symptoms and associated impairment in children. However, during the testing interval psychoeducational instruction in coping was administered, which may have contributed to the instability in these scores. Overall, the PARS reliability fares well in comparison with other self-, parent-, and clinicianrated measures of anxiety and suggests that the instrument will produce consistent scores when used by different (trained) examiners and will yield a relatively stable assessment of anxiety over time. Validity
Convergent/Divergent. Correlations between the PARS Total Score and indices of anxiety, depression, and externalizing behaviors provide preliminary support for the instrument’s convergent and divergent validity. The PARS Total Score showed the strongest correlation with the CGI-S—a clinician-rated measure of global anxiety severity and the measure closest to the underlying construct assessed by the PARS (i.e., global severity of anxiety). As expected, the PARS was also correlated with other clinician- and parent-rated measures of anxiety such as the HAM-A, SCARED-P, and CBCL Internalizing score. In contrast, correlations between the PARS and measures of externalizing behavior, inattention, and depression (CDRS-C) were low, supporting divergent validity.
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Correlations between each PARS individual severity item and measures assessing convergent validity revealed that the PARS Total Score had the strongest correlation for four of the seven measures (CGI-S, SCARED-P, CBCL Internalizing, CBCL Anxious/Depressed). However, the HAM-A was more strongly correlated with InterferenceHome (r = 0.55) than the PARS Total Score. Finally, the SCARED-C and the MASC, the two child-report measures of anxiety, had a stronger association (r = 0.38 and r = 0.27, respectively) with physical symptoms compared with the PARS Total Score. This finding has several interpretations. For instance, it may be that children are more able to endorse somatic complaints, which are more concrete, than report “cognitive” items related to severity or impairment. Alternatively, this finding may reflect that these self-report measures contain more somatic symptom items relative to interference or severity. Related, the lack of correspondence between the PARS Total Score and the MASC may reflect that the clinician-raters relied more on parent than child report in determining anxiety severity, particularly for younger children. Additional research is needed to test these hypotheses. Sensitivity to Treatment. Finally, the PARS also showed sensitivity to treatment effects. Specifically, the PARS showed a reduction in severity from pre- to posttreatment (RUPP, 2001). Moreover, the change in PARS scores paralleled changes in other measures of global severity (CGIS) and specific anxiety symptoms (HAM-A), although this may be due, in part, to shared rater effects. The absence of a significant correlation between changes in PARS Total Scores and changes in the MASC and SCARED from preto posttreatment was also unexpected. This finding may reflect the omission of the physical symptoms item from the PARS Total Score, given that these measures were found to be more highly associated with this item than the PARS Total Score. Clinical Applications
The PARS can be used for monitoring the course of anxiety symptoms and assessing the impact of treatments on the severity and interference of anxiety symptoms in youths. One advantage of the PARS relative to other clinician-rated pediatric anxiety instruments is that it allows the clinician/ researcher to assess the severity and impairment of anxiety symptoms across a broad spectrum of anxiety disorders. This is significant given the high degree of comorbidity and symptom overlap among anxiety disorders in youths. For example, although a child may have most difficulty with 1068
symptoms of SoP, he or she is likely also to have symptoms associated with SAD and GAD. Thus the PARS will enable researchers to assess the impact of treatment on symptoms of several anxiety disorders. Finally, because the PARS is easy to administer and time-efficient, it will be useful for clinicians in a variety of settings (e.g., psychiatry, psychology, primary care, schools, etc.). Administration of the PARS generally takes about 30 minutes. Limitations and Directions of Future Research
The promising findings of this study must be interpreted in the context of several methodological limitations. First, the study was done with a clinically anxious sample that was selected on the basis of stringent inclusion/exclusion criteria. Consequently, they may have been more severely affected than other clinically anxious samples given their interest in participating in a medication treatment study, with fewer comorbid nonanxiety disorders and higher socioeconomic status than families seen in community mental health centers. Therefore, whether the results are generalizable to community or other clinical samples is unknown. Second, there is a lack of data on discriminant validity. The next step in the development of the PARS is to establish appropriate norms for community and nonanxious clinical samples, such as youths suffering from depression or disruptive behavior disorders. Such data are necessary to determine scores that fall in the clinical range and to determine whether the PARS can successfully discriminate between youths from nonclinical, clinical nonanxious, and anxious groups. With respect to future directions, additional research and revisions will be needed on the instrument’s individual items. These revisions will likely address the following issues: (1) examining the utility of the individual severity items and reexamining the anchors associated with each item in light of possible ceiling effects; (2) examining the utility of the list of physical symptoms in order to determine how they should be grouped and to differentiate medication side effects from physical symptoms associated with an anxiety disorder; and, perhaps, (3) expanding the symptom list to include symptoms of obsessivecompulsive disorder, posttraumatic stress disorder, and acute stress disorder, to include all anxiety disorders in one instrument. Nevertheless, the PARS represents a useful measure for the assessment of childhood anxiety. The authors of this report, listed by study site: Mark A. Riddle, M.D., Golda S. Ginsburg, Ph.D., John T. Walkup, M.D., Michael J. Labelarte, M.D.,
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Johns Hopkins University; Daniel S. Pine, M.D., Mark Davies, M.P.H., Laurence Greenhill, M.D., Michael Sweeney, Ph.D., Rachel Klein, Ph.D., Columbia University and New York State Psychiatric Institute; Howard Abikoff, Ph.D., Sabine Hack, M.D., Brian Klee, M.D., New York University; James McCracken, M.D., Lindsey Bergman, Ph.D., John Piacentini, Ph.D., University of California at Los Angeles; John March, M.D., M.P.H., Scott Compton, Ph.D., Duke University; James Robinson, M.E.D., Thomas O’Hara, M.B.A., Sherryl Baker, Ph.D., Nathan Kline Institute; Benedetto Vitiello, M.D., Louise Ritz, M.B.A., Margaret Roper, M.P.H., National Institute of Mental Health. Dr. Riddle accepts responsibility for the overall content and integrity of the manuscript.
REFERENCES Abe K (1972), Phobias and nervous symptoms in childhood and maturity: persistence and associations. Br J Psychiatry 120:275–283 Abikoff H, Gittleman R (1985), Hyperactive children treated with stimulants: is cognitive training a useful adjunct? Arch Gen Psychiatry 42:953–961 Achenbach TM (1991), Manual for the 1991 CBCL/4–18 YSR and TRF Profiles. Burlington: University of Vermont Department of Psychiatry Ambrosini PJ (2000), Historical development and present status of the Schedule for Affective Disorders and Schizophrenia for School-Age Children (KSADS). J Am Acad Child Adolesc Psychiatry 39:49–58 Anastasi A, Urbina U (1997), Psychological Testing. Upper Saddle River, NJ: Prentice Hall Beidel DC, Christ MG, Long PJ (1991), Somatic complaints in anxious children. J Abnorm Child Psychol 19:659–670 Bird HR, Canino G, Rubio-Stipec M, Ribera JC (1987), Further measures of the psychometric properties of the Children’s Global Assessment Scale. Arch Gen Psychiatry 44:821–824 Birmaher B, Brent DA, Chiappetta L, Bridge J, Monga S, Baugher M (1999), Psychometric properties of the Screen for Child Anxiety Related Emotional Disorders (SCARED): a replication study. J Am Acad Child Adolesc Psychiatry 38:1230–1236 Birmaher B, Khetarpal S, Brent D et al. (1997), The Screen for Child Anxiety Related Emotional Disorders (SCARED): scale construction and psychometric characteristics. J Am Acad Child Adolesc Psychiatry 36:545–553 Clark D, Donovan J (1994), Reliability and validity of the Hamilton Anxiety Rating Scale in an adolescent sample. J Am Acad Child Adolesc Psychiatry 33:354–360 Cohen J, Cohen P (1975), Applied Multiple Regression/Correlation Analysis for the Behavioral Sciences. Hillsdale, NJ: Erlbaum Costello E, Angold A (1995), Epidemiology. In: Anxiety Disorders in Children and Adolescents, March J, ed. New York: Guilford, pp 109–124 Curry JF, Murphy LB (1995), Comorbidity of anxiety disorders. In: Anxiety Disorders in Children and Adolescents, March J, ed. New York: Guilford, pp 301–320 Francis G, Last CG, Strauss CC (1992), Avoidant personality disorder and social phobia in children and adolescents. J Am Acad Child Adolesc Psychiatry 31:1086–1089 Green B, Shirk S, Hanze D, Wanstrath J (1994), The Children’s Global Assessment Scale in clinical practice: an empirical evaluation. J Am Acad Child Adolesc Psychiatry 33:1158–1164 Greenhill L, Pine D, March J, Birmaher B, Riddle MA (1998), Assessment measures in anxiety disorders research. Psychopharmacol Bull 34:155–164 Guy W (1976), ECDEU Assessment Manual for Psychopharmacology Revised (Publication ADM 76-338). Washington, DC: US Department of Health, Education, and Welfare
Hamilton M (1959), The assessment of anxiety states by rating. Br J Med Psychol 32:50–55 Kaufman J, Birmaher B, Brent D et al. (1997), The Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version (K-SADS-PL): initial reliability and validity data. J Am Acad Child Adolesc Psychiatry 36:980–988 Kendall PC, Flannery-Schroeder E, Panicelli-Mindel SM, Southam-Gerow MA, Henin A, Warman M (1997), Therapy for youths with anxiety disorders: a second randomized clinical trial. J Consult Clin Psychol 65:366–380 Klein R, Koplewicz H, Kanner A (1992), Imipramine treatment of children with separation anxiety disorder. J Am Acad Child Adolesc Psychiatry 31:21–28 Leckman JF, Riddle MA, Hardin MT et al. (1989), The Yale Global Tic Severity Scale (YGTSS): initial testing of clinician-rated scale of tic severity. J Am Acad Child Adolesc Psychiatry 28:566–573 March J, Parker J, Sullivan K, Stallings P, Conners CKK (1997), The Multidimensional Anxiety Scale for Children (MASC): factor structure, reliability, and validity. J Am Acad Child Adolesc Psychiatry 36:554–565 March JS, Sullivan K (1999), Test-retest reliability of the Multidimensional Anxiety Scale for Children. J Anxiety Disord 13:349–358 Muris P, Meesters C, Merckelbach H, Sermon A, Zwakhalen S (1998), Worry in normal children. J Am Acad Child Adolesc Psychiatry 37:703–710 Muris P, Merckelbach H, Schmidt H, Mayer B (1999), The revised version of the Screen for Child Anxiety Related Emotional Disorders (SCARED-R): factor structure in normal children. Pers Individ Diff 26:99–112 Pine DS, Cohen P, Gurley D, Brook J, Ma Y (1998), The risk for early adulthood anxiety and depressive disorders in adolescents with anxiety and depressive disorders. Arch Gen Psychiatry 55:56–64 Poznanski EO, Grossman JA, Buchsbaum Y, Banegas M, Freeman J, Gibbons R (1984), Preliminary studies of the reliability and validity of the Children’s Depression Rating Scale. J Am Acad Child Psychiatry 23:191–197 Research Units on Pediatric Psychopharmacology Anxiety Study Group (2001), Fluvoxamine for the treatment of anxiety disorders in children and adolescents. N Engl J Med 344:1279–1285 Reynolds CR, Richmond B (1978), What I Think and Feel: a revised measure of children’s manifest anxiety. J Abnorm Child Psychol 6:271–280 Scahill L, Riddle MA, McSwiggin-Hardin M et al. (1997), Children’s YaleBrown Obsessive Compulsive Scale (CY-BOCS): reliability and validity. J Am Acad Child Adolesc Psychiatry 36:844–852 Shaffer D, Fisher P, Lucas CP, Dulcan MK, Schwab-Stone ME (2000), NIMH Diagnostic Interview Schedule for Children Version IV (NIMH DISCIV): description, differences from previous versions, and reliability of some common diagnoses. J Am Acad Child Adolesc Psychiatry 39:28–38 Shaffer D, Gould MS, Brasic J et al. (1983), A children’s global assessment scale (CGAS). Arch Gen Psychiatry 40:1228–1231 Shrout PE, Fleiss JL (1979), Intraclass correlations: uses in assessing rater reliability. Psychol Bull 86:420–428 Silverman WK, Albano AM (1996), The Anxiety Disorders Interview Schedule for Children-DSM-IV. San Antonio, TX: Psychological Corporation Silverman WK, Kurtines WM, Ginsburg GS, Weems CF, Rabian B, Serafini LT (1999), Contingency management, self-control, and education support in the treatment of childhood phobic disorders: a randomized clinical trial. J Consult Clin Psychol 67:675–687 Strauss CC, Lahey BB, Frick P, Frame CL, Hynd GW (1988), Peer social status of children with anxiety disorders. J Consult Clin Psychol 56:137–141 Welner Z, Reich W, Herjanic B, Jung KG, Amado H (1987), Reliability, validity, and parent–child agreement studies of the Diagnostic Interview for Children and Adolescents (DICA). J Am Acad Child Adolesc Psychiatry 26:649–653
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Anxiety disorders represent the most prevalent childhood psychiatric disorders, with estimates of point prevalence generally falling in the 3% to 13% range, depending on the degree of associated impairment (see Costello and Angold, 1995, for review). These disorders can severely impair the social, academic, familial, and personal functioning of affected children and negatively impact their families (e.g., Beidel et al., 1991; Francis et al., 1992; Strauss et al., 1988). In addition, existing longitudinal data, coupled with adults’ retrospective reports, suggest some continuity between child and adult disorders (Abe, 1972; Costello and Angold, 1995; Pine et al., 1998). In Accepted April 10, 2002. The study sites and authors are listed at the end of the text. The PARS and instructions for its administration are available via the Article Plus feature on the Journal’s Web site: www.jaacap.com. Supported by contracts from the NIMH to Johns Hopkins University (N01MH60016; PI: Dr. Riddle) and the Research Foundation for Mental Hygiene (N01MH60005; PI: Dr. Greenhill) and Solvay Pharmaceuticals; NIMH grants MH57503 and MH-01391 (Dr. Pine); NIMH RUPP contract N01MH70010 (Dr. McCracken); and National Center for Research Resources/NIH General Clinical Research Center grant M01 RR00052 (Johns Hopkins University School of Medicine). Reprint requests to Dr. Riddle, Division of Child and Adolescent Psychiatry, Johns Hopkins Children’s Center, Room 346, 600 North Wolfe Street, Baltimore, MD 21287-3325; e-mail: [email protected]. 0890-8567/02/4109–1061䉷2002 by the American Academy of Child and Adolescent Psychiatry. DOI: 10.1097/01.CHI.0000020259.43550.F4
light of the high prevalence of these disorders and the associated short- and long-term impairment, there is a critical need for developing reliable and valid methods for measuring and monitoring the severity of these disorders and their symptoms. The primary objective in developing the Pediatric Anxiety Rating Scale (PARS) was to address this need, particularly for clinician-rated assessments in treatment studies. Currently, the most common methods for identifying and measuring anxiety in youths are structured and semistructured diagnostic interviews, self-report rating scales, and clinician-rated instruments. Each of these methods is useful for specific purposes. For instance, structured diagnostic interviews, such as the Diagnostic Interview Schedule for Children (Shaffer et al., 2000), were primarily developed for use in epidemiological research to make diagnoses and are most useful for reliably ascertaining “externalizing” diagnoses, e.g., conduct disorder. Semistructured interviews, such as the Anxiety Disorders Interview Schedule for Children (ADIS-C) (Silverman and Albano, 1996), the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) (Ambrosini, 2000), and the Diagnostic Interview for Children and Adolescents (Welner et al., 1987), are used predominantly in clinical research and are particularly useful for making diagnoses. These instruments also facil-
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itate the gathering of information on a broad range of symptoms, impairment associated with specific diagnoses, duration of illness, and lifetime occurrences of illness. Newer versions of these instruments, e.g., the ADIS-C, assess severity of individual anxiety disorders and have been used as an outcome measure in treatment studies (Kendall et al., 1997; Silverman et. al., 1999). Self-report rating scales are most useful for screening and assessing the degree to which a child’s anxiety is normative in the context of developmental, gender, and cultural factors. In addition, these rating scales are useful for monitoring changes in anxiety symptoms over time or in relation to specific treatments. Examples of anxiety scales that assess a broad range of symptoms include the Revised Children’s Manifest Anxiety Scale (Reynolds and Richmond, 1978), the Multidimensional Anxiety Scale for Children (MASC) (March et al., 1997), and the Screen for Child Anxiety Related Emotional Disorders (SCARED) (Birmaher et al., 1997). Despite their advantages, self-report rating scales are dependent on the child’s cognitive abilities (i.e., to read and comprehend items), do not directly assess impairment, and are vulnerable to response biases inherent in self-report measures (Anastasi and Urbina, 1997). In contrast to parent reports or child-completed selfreports of anxiety, few clinician-rated instruments exist for assessing the severity of symptoms of pediatric anxiety disorders. Among the available instruments are the Hamilton Anxiety Rating Scale (HAM-A) (Hamilton, 1959) and the Children’s Yale-Brown Obsessive Compulsive Scale (CY-BOCS) (Scahill et al., 1997). The HAM-A assesses a broad range of anxiety symptoms; however, they are predominantly physiological or somatic in nature. More important, this measure was originally developed for use with adults; the psychometric properties have been examined in adolescents (Clark and Donovan, 1994), but it is unclear to what extent it accurately reflects current concepts regarding anxiety in pediatric samples. Although semistructured and structured diagnostic interviews, such as the ADIS-C, are clinician-administered and may assess severity of individual anxiety symptoms or disorders, these instruments typically do not provide an index of anxiety severity across disorders. Rather, these instruments link severity to one specific symptom or disorder (e.g., social phobia) based on the current (or a past) version of the DSM. Changes in DSM criteria for childhood anxiety disorders, the overlap of symptoms among anxiety disorders, and the high rates of comorbidity among anxiety disorders in youths (see Curry and Murphy, 1995, 1062
for review) highlight the limitation of this method for assessing the overall severity of anxiety symptoms. This issue is particularly relevant with respect to assessing global changes in anxiety severity in the context of treatment outcome studies that include children with more than one anxiety disorder (Greenhill et al., 1998). In summary, there are several methods for assessing anxiety symptoms in youths, each useful for specific purposes. However, to date there are no clinician-rated instruments for assessing both impairment and overall anxiety severity that cover the important domains of anxiety in youths. To fill this gap, the development of a new instrument was undertaken. The PARS was designed to assess the frequency, severity, and associated impairment of separation anxiety, social phobia, and generalized anxiety symptoms in youths aged 6–17 years. The purpose of the present study is to describe this instrument and present initial data on its psychometric properties. METHOD Construction and Description of the PARS The PARS and instructions for its administration are available via the Article Plus feature on the Journal’s Web site (www.jaacap.com). It was modeled after the CY-BOCS and the Yale Global Tic Severity Scale (YGTSS) (Leckman et al., 1989). Item content was derived as follows. First, items were generated predominantly from the DSMIV criteria for anxiety disorders including social phobia (SoP), separation anxiety disorder (SAD), and generalized anxiety disorder (GAD). Second, items were circulated among a group of expert child and adolescent psychiatrists and psychologists at the participating sites of the Research Units on Pediatric Psychopharmacology (RUPP) who were asked to comment on (1) face validity; (2) comprehensiveness; (3) overlap with other constructs, for example, disruptive behavior or depression; and (4) readability and clarity. After several iterations of this process, a 50-item “final version” was adopted for use in the RUPP fluvoxamine anxiety trial. This 50-item symptom checklist grouped items into the following categories: Social Interactions or Performance Situations (9 items), Separation (10 items), Generalized (8 items), Specific Phobia (4 items), Physical Signs and Symptoms (13 items), and Other (6 items). Each symptom is scored by the interviewing clinician as present or absent (yes/no) during the previous week. Information about symptoms is gathered from interviews with both the child and parent(s). These interviews may be conducted with child and parent together, as was done in the present study, or separately. Endorsed symptoms are then collectively (i.e., integrating both child and parent information) rated by the clinician on seven dimensions of severity, using a 6-point scale (0 for none, and 1–5 for minimal to extreme) for each dimension. These dimensions are (1) number of symptoms (none to more than 10), (2) frequency (none to several hours per day), (3) severity of distress associated with anxiety symptoms (none to extreme), (4) severity of physical symptoms (none to extreme), (5) avoidance (none to extreme), (6) interference at home (no interference to totally or almost totally unable to function at home), and (7) interference out of home (no interference to totally or almost totally unable to function out of home such as with peers
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or at school). A score of 3 on each of these 5-point scales indicates a clinically significant level of severity, avoidance, or interference. A PARS Total Score was calculated by summing five of the seven items. The “Number of Symptoms” item and the “Physical Symptoms” item were excluded. The “Number of Symptoms” item was excluded because of concern that it might not be related to severity of anxiety and might be highly skewed in this sample. The “Physical Symptoms” item was excluded because of concern that outcome data included ratings on subjects who were being treated with a selective serotonin reuptake inhibitor (SSRI). Common adverse events of SSRIs include symptoms that are identical with some of the symptoms in the PARS Symptom Checklist: “sweating”; “feels sick to stomach, nausea or abdominal distress”; “restlessness or feeling keyed-up or on edge”; “sleep disturbance, especially difficulty falling asleep.” Thus, throughout this article, PARS Total Score refers to a sum of the remaining five items. Participants The current study was conducted in two stages. The first stage examined the interrater reliability of the PARS, while the second stage examined test-retest reliability and validity. To examine interrater reliability, 16 children aged 5–15 years (63% males; mean age 10.5 years) were interviewed with the PARS. Of these children, 11 were white, 1 was African American, 2 were Hispanic American, and 2 were Asian American. Seven of these children also participated in the RUPP anxiety treatment study (described below). The second stage of this study was conducted within the context of a double-blind, placebo-controlled clinical trial of fluvoxamine for youths with SoP, SAD, and GAD (RUPP, 2001). Five RUPP sites were involved in that study: Duke University, Johns Hopkins University, New York State Psychiatric Institute/Columbia University, New York University, and University of California, Los Angeles. Participants included 128 children, aged 6–17 years (mean = 10.8 years; 49% female; 63% white), with a current DSM-IV diagnosis of SoP, SAD, or GAD, based on child and parent K-SADS interview with a trained clinician. Sites recruited participants from a variety of sources, including mental health settings and newspaper advertisements. Other inclusion criteria were as follows: clinically significant impairment as assessed with a Children’s Global Assessment Scale (CGAS) score less than 60; and availability of both a parent and the child for weekly visits. Exclusion criteria included current use of any illicit or prescribed psychoactive substance; current diagnoses of either major depressive disorder, Tourette’s disorder, obsessive-compulsive disorder, posttraumatic stress disorder, conduct disorder, or panic disorder; any past or current history of mania, psychosis, or pervasive developmental disorder; current suicidal ideation; mental retardation as assessed with the Kaufman Brief Intelligence Test (IQ < 70); previous use of an SSRI in appropriate doses; and a diagnosis of attention-deficit/hyperactivity disorder that required pharmacological treatment. Table 1 summarizes the characteristics of participants in the entire sample. Measures Schedule for Affective Disorders and Schizophrenia for School-Age Children. Inclusion/exclusion criteria for psychiatric diagnoses were assessed with the K-SADS (Ambrosini, 2000; Kaufman et al., 1997), administered by experienced clinicians. The K-SADS possesses good reliability and validity (Ambrosini, 2000). The entire K-SADS interview was administered during intake into the treatment study. Children’s Global Assessment Scale. The CGAS (Bird et al., 1987; Shaffer et al., 1983) is a modification of the adult GAS and provides a measure of global impairment and functioning over the previous month. The
TABLE 1 Sociodemographic and Clinical Characteristics of Entire Sample (N = 128) Mean age (years) Gender (female) Ethnicity White Hispanic African American (non-Hispanic) Other Total family income <$25,000 $25,000–39,999 $40,000–59,000 >$60,000 Refused/unknown Diagnosis (based on K-SADS) SoP only SAD only GAD only SoP and SAD only SoP and GAD only SAD and GAD only SoP, SAD, and GAD
10.8 63 (49.2) 81 (63.3) 24 (18.8) 9 (7.0) 14 (10.9) 19 (14.8) 20 (15.6) 18 (14.1) 55 (43.0) 16 (12.5) 26 (20.3) 18 (14.1) 5 (3.9) 11 (8.6) 21 (16.4) 21 (16.4) 26 (20.3)
Note: With the exception of age, values represent n (%). K-SADS = Schedule for Affective Disorders and Schizophrenia for School-Age Children; SoP = social phobia; SAD = separation anxiety disorder; GAD = generalized anxiety disorder. scale ranges from 1 (lowest) to 100 (highest). Ample evidence exists supporting the psychometric soundness of the scale (Green et al., 1994). Clinician’s Global Impression of Severity Scale. The Clinician’s Global Impression of Severity Scale (CGI-S) (Guy, 1976) was used to assess global severity of anxiety using a 7-point scale, ranging from normal to most extreme. This measure was completed at major assessment points by a clinician to assess changes in anxiety severity. Clinician’s Global Impression of Improvement Scale. The Clinician’s Global Impression of Improvement Scale (CGI-I) was used to assess overall global change at each visit using data from all other measures in the study. An 8-point scale (Abikoff and Gittelman, 1985; Klein et al., 1992) that is similar to the traditional 7-item scale (Guy, 1976), but allows for greater discrimination among levels of response in treatment responders, was used (1 = completely well, recovered; 2 = much improved; 3 = improved; 4 = slightly improved; 5 = unchanged; 6 = slightly worse; 7 = worse; 8 = much worse). Multidimensional Anxiety Scale for Children. The MASC (March et al., 1997) is a 39-item, 4-point, Likert, self-report rating scale that has shown robust psychometric properties in studies of clinical and nonclinical samples. The MASC includes four factors derived to match the population factor structure of anxiety: physical symptoms (tense/ restless and somatic/autonomic subfactors), social anxiety (humiliation/ rejection and public performance subfactors), harm avoidance (anxious coping and perfectionism subfactors), and separation/panic anxiety. Three-week test-retest reliability for the MASC is good as shown by intraclass correlation coefficient (ICC) = 0.79 in clinical (March et al., 1997) and 0.88 in school-based samples (March and Sullivan, 1999). Screen for Child Anxiety Related Emotional Disorders. The SCARED (Birmaher et al., 1997, 1999) is a 41-item, child- and parent-report instrument that assesses DSM-IV symptoms of panic, SAD, SoP, and GAD and symptoms of school refusal. The SCARED has shown good
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psychometric properties in two different large clinical samples (Birmaher et al., 1997, 1999) and in a community sample (Muris et al., 1998, 1999). For instance, data obtained on an outpatient clinic sample of 341 youths (9–18 years, mean = 14.5) indicated test-retest reliability coefficients ranging from 0.70 to 0.90 (over a 4-day to 15week period) and internal consistency coefficients of the subscales ranged from 0.74 to 0.89 (Birmaher et al., 1997). The SCARED demonstrated good sensitivity and specificity in a study of children with anxiety, depressive, and disruptive disorders, and it was sensitive to treatment effects (Birmaher et al., 1999). Children’s Depression Rating Scale. The Children’s Depression Rating Scale (CDRS) (Poznanski et al., 1984) is a clinician-administered screening tool that assesses 17 symptom areas of depression (e.g., sleep, social withdrawal, school). The CDRS is widely used and has established psychometric properties. For instance, test-retest reliability over a 2-week period was 0.86, interrater reliability was 0.92 (for the summary score), and the Cronbach α was .85. Moreover, the CDRS discriminates between depressed and nondepressed psychiatric patients and is correlated with other measures of depression and suicidal behavior (Poznanski et al., 1984). Hamilton Anxiety Rating Scale. The HAM-A (Hamilton, 1959) is a 14-item, clinician-administered measure of anxiety symptoms with a focus on somatic symptoms. The measure has demonstrated reliability and construct validity with adults and adolescents. Specifically, in a sample of adolescents, interrater reliability was 0.92 and the Cronbach α was .86 (Clark and Donovan, 1994). The HAM-A was also correlated with self-report measures of anxiety and fear and discriminated between nonclinical, clinical, and clinically anxious youths. Child Behavior Checklist. The Child Behavior Checklist (CBCL) (Achenbach, 1991), a widely used parent-completed measure, assesses a broad range of child behavior problems. The measure yields a Total Problem Behavior score, two broad-band scores (Internalizing and Externalizing), and several narrow-band scale scores (e.g., Anxious/ Depressed, Inattention, etc.). Procedure Prior to participation in this study, all parents signed informed consents; children over age 6 signed assents. A comprehensive pretreatment evaluation was conducted which included the diagnostic interview and additional measures to assess inclusion/exclusion criteria and outcome measures. The pretreatment evaluation was completed over three visits, which spanned a 3- to 4-week period of time. Generally, at the first visit the K-SADS, PARS, CGI, CGAS, and HAM-A were administered. On the second visit, parents completed the CBCL and medical assessments were conducted (e.g., medical history, physical examination, blood draw). On the third visit, demographics, family history, and intellectual assessments were conducted. At baseline, the CDRS, K-SADS, PARS, HAM-A, CGI, CGAS, SCARED, MASC, other self-report and medical procedures were completed. Thus, prior to treatment, the PARS was administered on two separate occasions by the same pediatric psychiatrist or psychologist: at the screening evaluation (the beginning of the 3-week period) and at the baseline (randomization) evaluation (the end of the 3- to 4-week period). At each visit, the PARS was conducted prior to all other rating scales. For the interrater reliability part of the study, live interviews were conducted and videotaped. Clinicians who were present during the interview provided ratings. All other ratings were from clinicians who watched the videotaped session. During the interviews, children were administered the PARS first, then parents. Parents and children were brought together to sort out significant discrepancies. There were a total of 11 raters from the 5 sites, 9 child and adolescent psychiatrists
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and 2 clinical child psychologists (this group of raters participated in a training session on the use of the PARS and completed all assessments described above); however, 5 of the 11 raters were unable to rate all subjects. Of these five, two raters were available for seven videotaped interviews only; one rater was available for the seven videotaped interviews and two live interviews; and one rater was available for seven videotaped interviews and six live interviews. During the treatment phase, the treating child and adolescent psychiatrist, who was blind to treatment condition, saw each child and a parent on a weekly basis for the first 6 weeks of the trial and again at week 8. At each visit, psychiatrists completed three tasks: (1) they administered the supportive psychoeducational therapy to children and families, (2) they conducted a clinical assessment of anxiety symptoms using the PARS and other instruments, and (3) they assessed adverse events. The rating scales described above were also completed at week 4 and week 8 treatment visits. Primary Statistical Analyses Reliability. Internal consistency was calculated using the Cronbach α for the five items (see below) that comprise the PARS Total Score. ICCs (Shrout and Fleiss, 1979) were calculated for the Total Score and individual severity items to assess interrater and test-retest reliability, which was examined over the 1- to 4-week period between screening and baseline. Validity. Convergent validity was evaluated by calculating Pearson correlation coefficients for the PARS with other anxiety measures including the MASC, SCARED, HAM-A, and CBCL (i.e., Anxious/Depressed and total Internalizing scores). To examine divergent validity, we examined the correlation between the PARS Total Score and scores on the CDRS and the CBCL Externalizing and Inattention subscale scores. Statistically significant and relatively large correlations were expected for convergent, but not divergent, validity. Differences between dependent correlations were tested using the method described by Cohen and Cohen (1975). To assess the PARS sensitivity to change, we examined the correspondence of changes in PARS scores to changes in the CGII, CGI-S, CGAS, and other measures of anxiety before and after the 8week, double-blind, placebo-controlled study of fluvoxamine. All children were included in each analysis as long as the data were not missing. Systematic missing data were not a problem, although missing data were evident for most measures. Statistical significance is reported at the 5% level.
RESULTS Internal Validity
Descriptive Statistics. The means and standard deviations of the PARS scores for the seven individual severity items and the five-item Total Score for boys, girls, and the total sample are presented in Table 2. In general, the means (and modes) for the PARS individual items were above the mid-point (2.5) and slightly positively skewed on the 6-point (0–5) scale. The PARS Total Score was unimodal and normally distributed. A comparison of PARS Total Scores between younger and older children using the total sample showed no significant differences. The t test comparisons between boys and girls on the PARS Total revealed
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TABLE 2 Mean Scores (and Standard Deviations) on the PARS at Baseline Boys (n = 64)
PARS Item Number of Symptoms Symptom Frequency Severity-Distress Severity-Somatic Avoidance Interference-Home Interference-Other Total (5-item)a
4.8 3.9 4.0 2.8 3.8 3.4 3.4 18.5
(0.6) (1.0) (0.8) (1.2) (1.0) (1.2) (1.2) (3.5)
Girls (n = 63) 4.8 3.9 4.0 2.6 4.0 3.4 3.1 18.8
Total (n = 127)
(0.5) (1.0) (0.7) (1.5) (0.8) (1.0) (1.1) (3.0)
4.8 3.9 4.0 2.7 3.9 3.4 3.5 18.7
(0.6) (1.0) (0.7) (1.4) (0.9) (1.1) (1.2) (3.21)
Note: Items range from 0 (none) to 5 (extreme); Total Score range is 0 to 25. PARS = Pediatric Anxiety Rating Scale. a Two items, Number of Symptoms and Physical Symptoms, were excluded from five-item Total.
no significant differences—both for the total sample and within younger (ages 6–12) or older (ages 13–17) age groups. No differences were found on any PARS items between whites and Hispanics (the largest minority group in the sample). The correlation between PARS Total Scores and income was nonsignificant (r = –0.15). Internal Consistency. The Cronbach α coefficient for the five items comprising the PARS Total Score at baseline was .64, indicating that the PARS items are associated but not redundant. Correlations among the PARS seven items and the PARS five-item Total Score severity items at baseline are presented in Table 3. Correlation coefficients among the seven severity items ranged from 0.08 (between total number of symptoms and interference out of home) and 0.45 (between interference at home and distress). Most of the seven individual severity items were moderately correlated with the PARS Total Score (range, 0.24–0.68). Correlations among the individual PARS severity items were quite varied, ranging
from 0.08 (Interference-Home and Interference-Other) and 0.50 (Avoidance and Interference-Other). Reliability
Interrater Reliability. The ICC for the PARS Total Score across raters was 0.97. Table 4 displays the ICCs for each of the seven severity items. Test-Retest Reliability. The test-retest reliability coefficient between screen and baseline (mean = 24.7 ± 14.7 days) for the PARS Total Score was 0.55 for the total sample. ICCs for each item ranged from 0.35 (Avoidance) to 0.59 (Interference-Home). These coefficients are presented in Table 5. Validity: Convergent and Divergent
To assess convergent validity, we calculated Pearson correlations between the PARS Total Score at baseline and other measures of anxiety, including (1) CGI-S, (2) HAM-A, (3) MASC, (4) SCARED-child and -parent versions, and (5) CBCL Anxious/Depressed subscale and Internalizing subscales. These results are presented in Table 6. The PARS Total score was moderately correlated with the other clinician- and parent-rated measures of anxiety, such as the CGI-S (clinician rating of anxiety severity), HAM-A, and SCARED-P. Correlations were generally weakest with the two child self-report measures of anxiety (MASC and SCARED-C). In additional analyses, each PARS severity item was correlated with the above measures (correlations available from the authors). Using a minimum criterion of r = 0.40, results indicated that the CGI-S was correlated with PARS Distress (0.41) and Interference-Out of Home (0.55), and the HAM-A was correlated with Interference-Home (0.55), Physical Symptoms (0.46), and Distress (0.43). No other correlations surpassed this criterion.
TABLE 3 Correlations Among PARS Seven Items and PARS Five-Item Total Score at Baseline 1 1. 2. 3. 4. 5. 6. 7. 8.
Number of Symptoms Frequency Distress Physical Symptoms Avoidance Interference-Home Interference-Other Total Score
1
2 0.34*** 1
3 0.41*** 0.37*** 1
4 0.18* 0.13 0.32*** 1
5
6
7
8
0.20* 0.13 0.18* 0.06 1
0.36*** 0.39*** 0.45*** 0.14 0.19* 1
0.08 0.15 0.34*** 0.19* 0.50*** 0.08 1
0.41*** 0.63*** 0.68*** 0.24* 0.62*** 0.65*** 0.66*** 1
Note: PARS = Pediatric Anxiety Rating Scale. * p < .05; *** p < .001.
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TABLE 5 ICC Test-Retest Coefficients and Means at Screen and Baseline on the PARS
TABLE 4 ICC Interrater Reliability Coefficients on the PARS PARS
ICC a
Number of Symptoms Frequency Distress Physical Symptoms Avoidance Interference-Home Interference-Other Total (5-item)
0.78 0.92 0.96 0.89 0.92 0.89 0.92 0.97
Note: PARS = Pediatric Anxiety Rating Scale; ICC = intraclass correlation coefficient. a All ICC values significant at p < .001.
Divergent validity was assessed in a preliminary manner by correlating the PARS Total Score at baseline with the baseline CDRS and the CBCL Inattention and Externalizing subscales. These correlations, which appear in Table 6, were relatively small (0.18–0.30). A test of the difference in correlations between the PARS Total Score and the CBCL Internalizing (0.40) and CBCL Externalizing (0.22) scales revealed that the correlation between the PARS and the CBCL Internalizing scale was significantly larger (t119 = 2.23, p = .03). Sensitivity to Treatment. We also examined correlations between change in the PARS Total Score and change after treatment in (1) global assessment of functioning (CGAS), (2) clinician-rated global anxiety severity (CGI-S), (3)
PARS
ICC a
Screen (SD)
Number of Symptoms Frequency Distress Physical Symptoms Avoidance Interference-Home Interference-Other Total Score (5-item)
0.48 0.42 0.37 0.45 0.35 0.59 0.54 0.55
4.6 3.7 3.8 2.8 3.7 3.4 3.3 18.0
Baseline (SD)
(0.8) (1.1) (0.6) (1.3) (0.9) (1.0) (1.2) (3.1)
4.8 3.9 4.0 2.7 3.9 3.4 3.5 18.7
(0.6) (1.0) (0.7) (1.4) (0.9) (1.1) (1.2) (3.21)
Note: PARS = Pediatric Anxiety Rating Scale; ICC = intraclass correlation coefficient. a All ICC values significant at p < .001.
clinician-rated anxiety scale (HAM-A), and (4) self-reports and parent reports of anxiety (i.e., MASC, SCARED-C, and SCARED-P). Change in the PARS Total Score was significantly correlated with pre-post treatment changes in the CGAS (0.78), CGI-S (0.53), and HAM-A (0.41), but uncorrelated with changes in the MASC (0.03), SCARED-C (0.02), or SCARED-P (0.03). DISCUSSION
The purpose of this study was to describe the development and initial psychometric properties of the PARS, a clinician-rated instrument for assessing the severity of symptoms common to a broad range of pediatric anxiety disorders. The PARS was designed to fill a gap among
TABLE 6 Correlations Between PARS Total Score and Measures of Internalizing and Externalizing Behaviors at Baseline Scale Convergent validity CGI-S HAM-A SCARED-P CBCL-I CBCL-A SCARED-C MASC Divergent validity CDRS-P CBCL-In CBCL-E CDRS-C
Construct
Source
Mean
(SD)
R
Anxiety Anxiety Anxiety Internalizing Anxiety Anxiety Anxiety
Clinician Clinician Parent Parent Parent Child Child
5.06 17.25 36.60 20.36 11.30 31.52 54.27
(0.81) (7.67) (13.38) (9.77) (5.48) (13.79) (18.58)
0.61*** 0.49*** 0.46*** 0.41*** 0.36*** 0.32*** 0.22*
Depression Inattention Externalizing Depression
Clinician Parent Parent Clinician
30.44 6.93 13.16 28.49
(10.52) (4.60) (9.68) (9.16)
0.33*** 0.27** 0.22* 0.18*
Note: CGI-S = Clinician’s Global Impression of Severity Scale; HAM-A = Hamilton Anxiety Rating Scale; SCARED-P = Screen for Child Anxiety Rated Emotional Disorders-Parent; CBCL-I = Child Behavior Checklist-Internalizing; CBCL-A = Child Behavior Checklist-Anxiety; SCARED-C = Screen for Anxiety Related Emotional Disorders-Child; MASC = Multidimensional Anxiety Scale for Children; CDRS-P = Children’s Depression Rating Scale-Parent; CBCL-In = Child Behavior Checklist-Inattention; CBCL-E = Child Behavior Checklist-Externalizing; CDRS-C = Children’s Depression Rating Scale-Child. * p < .05; ** p < .01; *** p < .001.
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existing child anxiety assessment tools, and our findings suggest it holds considerable promise as both a research and clinical instrument. Descriptive Statistics and Selection of Severity Items
Modeled after the CY-BOCS and YGTSS, the current version of the PARS has 50 symptom items and 7 severity/ impairment items. A total score was obtained by summing five of the severity items. For reasons presented in the “Method” section, two items, “Number of Symptoms” and “Severity of Physical Symptoms,” were not included in the calculation of the total score. Although the distribution of the PARS Total Score was “normal,” most of the individual severity items were positively skewed. For instance, the modal score for the “Number of Symptoms” item was 5.0, indicating that most youths with SoP, SAD, and/or GAD in the present sample had greater than 10 symptoms. Consequently, this item should be dropped from the PARS or new anchors need to be established and this item then needs to be reevaluated. The “Severity of Physical Symptoms” item was dropped from the total score because many of the physical symptoms of anxiety are similar to adverse events of psychotropic medications, particularly the SSRIs (e.g., “trembling and shaking,” “sweating,” “feels sick to stomach, nausea or abdominal distress”). Obviously, for assessment of anxiety in children not receiving medication, this would not be an issue. Thus further work is needed to clarify the value of including physical symptoms in the PARS Total Score. Comparisons between boys and girls and younger and older children on the PARS Total Score revealed no significant differences. The absence of gender and age differences may reflect the nature of the present sample. Both boys and girls in this study met strict inclusion/exclusion criteria and thus were selected to surpass a prespecified level of severity of anxiety. Correlations among the PARS severity items and PARS Total Score varied, ranging from 0.08 (between total number of symptoms and interference out of home) to 0.45 (between interference at home and anxiety severity). The five individual severity items that comprise the Total Score were uniformly correlated with the PARS Total Score (range, 0.62–0.68). Of note, the two omitted items, “Number of Symptoms” and “Severity of Physical Symptoms,” showed the lowest correlation with the PARS Total Score, suggesting that they may be a poor proxy of overall severity or impairment. The low correlations for these two items support the decision to omit them in cal-
culating the PARS Total Score. Alternatively, because the PARS Total Score contains the other five items, it is possible that the other five correlations are artificially elevated. As noted earlier, correlations among the individual PARS severity items were quite varied, ranging from 0.08 (Interference-Home and Interference-Other) and 0.50 (Avoidance and Interference-Other). The pattern of correlations suggests that children who report a high number of symptoms are more likely to experience them more often and report more distress and interference at home. In addition, avoidance due to anxiety was most closely linked to higher levels of distress and interference outside of the home (e.g., with friends, at school). Finally, the absence of a relation between the two interference items suggests that children’s impairment may be domain-specific. Reliability
In general, the PARS demonstrated acceptable psychometric properties with respect to interrater reliability (high, ICC = 0.97), internal consistency (adequate, α = .64), and test-retest reliability (fair, ICC = 0.55). Regarding test-retest reliability, to some extent these lower coefficients reflect expected instability of anxiety symptoms and associated impairment in children. However, during the testing interval psychoeducational instruction in coping was administered, which may have contributed to the instability in these scores. Overall, the PARS reliability fares well in comparison with other self-, parent-, and clinicianrated measures of anxiety and suggests that the instrument will produce consistent scores when used by different (trained) examiners and will yield a relatively stable assessment of anxiety over time. Validity
Convergent/Divergent. Correlations between the PARS Total Score and indices of anxiety, depression, and externalizing behaviors provide preliminary support for the instrument’s convergent and divergent validity. The PARS Total Score showed the strongest correlation with the CGI-S—a clinician-rated measure of global anxiety severity and the measure closest to the underlying construct assessed by the PARS (i.e., global severity of anxiety). As expected, the PARS was also correlated with other clinician- and parent-rated measures of anxiety such as the HAM-A, SCARED-P, and CBCL Internalizing score. In contrast, correlations between the PARS and measures of externalizing behavior, inattention, and depression (CDRS-C) were low, supporting divergent validity.
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Correlations between each PARS individual severity item and measures assessing convergent validity revealed that the PARS Total Score had the strongest correlation for four of the seven measures (CGI-S, SCARED-P, CBCL Internalizing, CBCL Anxious/Depressed). However, the HAM-A was more strongly correlated with InterferenceHome (r = 0.55) than the PARS Total Score. Finally, the SCARED-C and the MASC, the two child-report measures of anxiety, had a stronger association (r = 0.38 and r = 0.27, respectively) with physical symptoms compared with the PARS Total Score. This finding has several interpretations. For instance, it may be that children are more able to endorse somatic complaints, which are more concrete, than report “cognitive” items related to severity or impairment. Alternatively, this finding may reflect that these self-report measures contain more somatic symptom items relative to interference or severity. Related, the lack of correspondence between the PARS Total Score and the MASC may reflect that the clinician-raters relied more on parent than child report in determining anxiety severity, particularly for younger children. Additional research is needed to test these hypotheses. Sensitivity to Treatment. Finally, the PARS also showed sensitivity to treatment effects. Specifically, the PARS showed a reduction in severity from pre- to posttreatment (RUPP, 2001). Moreover, the change in PARS scores paralleled changes in other measures of global severity (CGIS) and specific anxiety symptoms (HAM-A), although this may be due, in part, to shared rater effects. The absence of a significant correlation between changes in PARS Total Scores and changes in the MASC and SCARED from preto posttreatment was also unexpected. This finding may reflect the omission of the physical symptoms item from the PARS Total Score, given that these measures were found to be more highly associated with this item than the PARS Total Score. Clinical Applications
The PARS can be used for monitoring the course of anxiety symptoms and assessing the impact of treatments on the severity and interference of anxiety symptoms in youths. One advantage of the PARS relative to other clinician-rated pediatric anxiety instruments is that it allows the clinician/ researcher to assess the severity and impairment of anxiety symptoms across a broad spectrum of anxiety disorders. This is significant given the high degree of comorbidity and symptom overlap among anxiety disorders in youths. For example, although a child may have most difficulty with 1068
symptoms of SoP, he or she is likely also to have symptoms associated with SAD and GAD. Thus the PARS will enable researchers to assess the impact of treatment on symptoms of several anxiety disorders. Finally, because the PARS is easy to administer and time-efficient, it will be useful for clinicians in a variety of settings (e.g., psychiatry, psychology, primary care, schools, etc.). Administration of the PARS generally takes about 30 minutes. Limitations and Directions of Future Research
The promising findings of this study must be interpreted in the context of several methodological limitations. First, the study was done with a clinically anxious sample that was selected on the basis of stringent inclusion/exclusion criteria. Consequently, they may have been more severely affected than other clinically anxious samples given their interest in participating in a medication treatment study, with fewer comorbid nonanxiety disorders and higher socioeconomic status than families seen in community mental health centers. Therefore, whether the results are generalizable to community or other clinical samples is unknown. Second, there is a lack of data on discriminant validity. The next step in the development of the PARS is to establish appropriate norms for community and nonanxious clinical samples, such as youths suffering from depression or disruptive behavior disorders. Such data are necessary to determine scores that fall in the clinical range and to determine whether the PARS can successfully discriminate between youths from nonclinical, clinical nonanxious, and anxious groups. With respect to future directions, additional research and revisions will be needed on the instrument’s individual items. These revisions will likely address the following issues: (1) examining the utility of the individual severity items and reexamining the anchors associated with each item in light of possible ceiling effects; (2) examining the utility of the list of physical symptoms in order to determine how they should be grouped and to differentiate medication side effects from physical symptoms associated with an anxiety disorder; and, perhaps, (3) expanding the symptom list to include symptoms of obsessivecompulsive disorder, posttraumatic stress disorder, and acute stress disorder, to include all anxiety disorders in one instrument. Nevertheless, the PARS represents a useful measure for the assessment of childhood anxiety. The authors of this report, listed by study site: Mark A. Riddle, M.D., Golda S. Ginsburg, Ph.D., John T. Walkup, M.D., Michael J. Labelarte, M.D.,
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Johns Hopkins University; Daniel S. Pine, M.D., Mark Davies, M.P.H., Laurence Greenhill, M.D., Michael Sweeney, Ph.D., Rachel Klein, Ph.D., Columbia University and New York State Psychiatric Institute; Howard Abikoff, Ph.D., Sabine Hack, M.D., Brian Klee, M.D., New York University; James McCracken, M.D., Lindsey Bergman, Ph.D., John Piacentini, Ph.D., University of California at Los Angeles; John March, M.D., M.P.H., Scott Compton, Ph.D., Duke University; James Robinson, M.E.D., Thomas O’Hara, M.B.A., Sherryl Baker, Ph.D., Nathan Kline Institute; Benedetto Vitiello, M.D., Louise Ritz, M.B.A., Margaret Roper, M.P.H., National Institute of Mental Health. Dr. Riddle accepts responsibility for the overall content and integrity of the manuscript.
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