|Year : 2010 | Volume
| Issue : 2 | Page : 72-80
Validation of the children's depression rating scale- revised for adolescents in primary-care pediatric use in India
Mona M Basker1, Paul Swamidhas Sudhakar Russell2, Sushila Russell2, Prabhakar D Moses1
1 Department of Pediatrics, Division of Child Health, Christian Medical College, Vellore, Tamil Nadu, India
2 Department of Psychiatry, Child and Adolescent Psychiatry Unit, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Web Publication||28-Mar-2012|
Paul Swamidhas Sudhakar Russell
Child and Adolescent Psychiatry Unit, Department of Psychiatry, Christian Medical College, Vellore - 632 002, Tamil Nadu
Background: Adolescent depression needs to be identified and treated in the primary care settings. There is no clinician-rated measure validated in India for identifying depression among adolescents. Aim: We studied the diagnostic accuracy, reliability, and validity of Children's Depression Rating Scale - Revised (CDRS-R) for primary care pediatrics. Setting and Design: Prospective study in three schools in Southern India. Materials And Methods: Adolescents recruited were administered the CDRS-R by a pediatrician and clinical psychologist along with Beck Depression Inventory (BDI) for convergent validity. Impact of Event Scale (IES) for divergent validity and the ICD-10 clinical diagnosis of depressive disorders using modified Kiddie-SADS-Present and Lifetime Version (K-SADS-PL) interview as reference standard were administered by a psychiatrist independently. Appropriate statistical analyses for diagnostic accuracy, reliability, and validity were done. Results: A cut-off score of 30 (sensitivity = 83%, specificity = 84%; AUC in ROC = 87%) in CDRS-R is suggested for diagnosing depression. The inter-rater reliability (r = 0.73) and test-retest reliability (r = 0.98) was good. In addition to the adequate face and content validity, CDRS-R had good internal consistency (α = 0.76), high convergent (r = 0.71; P = 0.001), and divergent validity (r = 0.28; P = 0.20). There was moderate concordance with the reference standard of ICD-10 diagnosis (45.5%) in identifying depression and CDRS-R discriminated 80% of the other psychiatric morbidity. The six-factor structure explained 60.6% of variance. Conclusion: The CDRS-R showed strong psychometric properties and is now available for use in the primary-care pediatric practice in India.
Keywords: Adolescents, depressive disorder, India rating scales
|How to cite this article:|
Basker MM, Russell PS, Russell S, Moses PD. Validation of the children's depression rating scale- revised for adolescents in primary-care pediatric use in India. Indian J Med Sci 2010;64:72-80
|How to cite this URL:|
Basker MM, Russell PS, Russell S, Moses PD. Validation of the children's depression rating scale- revised for adolescents in primary-care pediatric use in India. Indian J Med Sci [serial online] 2010 [cited 2013 May 18];64:72-80. Available from: http://www.indianjmedsci.org/text.asp?2010/64/2/72/94403
| ¤ Introduction|| |
In India the prevalence of depression among adolescents is 11.2%.  The WHO classifies depression as a Priority Mental Health Disorder of adolescence to be addressed at the primary-care pediatric settings.  Therefore, identifying and treating depression becomes the responsibility of pediatricians.  Currently neither screening nor diagnosis of depressive disorders is part of primary care of adolescents.  The reasons associated with decreased identification of depression in primary care is the lack of measures validated for such settings and low rate of use when such measures exist. 
Clinician-rated measures for adolescent depression in primary care settings are unavailable in India. In our previous study we validated the self-rated measure of Beck Depression Inventory  for use in India.  Among the clinician-rated measures for depression, the Children's Depression Rating Scale-Revised (CDRS-R) has been widely acclaimed. ,,, In this study we validate CDRS-R for primary-care pediatric use in India.
| ¤ Materials and Methods|| |
Setting and sample
All adolescents were recruited from three schools in Southern India for the study if they were in the 11 th grade (to avoid the symptoms of depression due to educational stress of appearing for board examination in the 10 th as well as the 12 th grades), and able to read and write English atleast at sixth grade level. Those adolescents who satisfied the selection criteria (N = 181) were assessed and interviewed using the following psychometrically validated measures for the Indian adolescents and internationally used clinical diagnostic criteria respectively.
Children's Depression Rating Scale-Revised (CDRS-R), the measure for validation in this study, is used as an objective, clinician-rated measure for diagnosing depression, its severity and treatment response.  CDRS-R has 17 symptom areas: impaired schoolwork, difficulty having fun, social withdrawal, appetite disturbance, sleep disturbance, excessive fatigue, physical complaints, irritability, excessive guilt, low self-esteem, depressed feelings, morbid ideas, suicidal ideas, excessive weeping, depressed facial affect, listless speech, and hypoactivity. CDRS-R total score ranges from 17 to 113 and fourteen of the 17 items are rated on a scale from 1 to 7, with an item score of 3 suggestive of mild, 4 or 5 moderate, and 6 or 7 severe symptoms. The other three items are rated on a scale from 1 to 5. Both children and their parents provide input into the first 14 items of the scale. A child's nonverbal behavior is rated by the observer for items 15 through 17. CDRS-R can be administered in 15-20 minutes. Although the measure was originally designed for use among 6- to 12-year-old children it has been successfully used with adolescents.  CDRS-R has been validated in other languages and culture and a short version of the tool is also available. , CDRS-R is useful in tracking the rate of recovery in depressed adolescents as well. 
Beck Depression Inventory (BDI) is a self-rated 21 item depression inventory, with each item rated in a 0-3 scale of increasing intensity and the total score compared to a key to determine the depression's severity.  While the children's version of BDI named Children's Depression Inventory (CDI) is used in younger age groups, BDI can be administered for adolescents above 14 years as the reading level of the measure is only at sixth grade level and can be completed in about 10 minutes. The reliability and validity of BDI has been demonstrated with adolescents in other countries including India. The validity of BDI when used in primary-care pediatric setting in India has been documented and a score of ≥22 suggests the presence of depressive disorder.  BDI was used in the study to determine the convergent validity of CDRS-R.
Impact of Events scale (IES) is an eight-item measure that has been validated for identifying adolescents with posttraumatic stress disorder (PTSD) in India  and was used to determine the divergent validity of CDRS-R.
The ICD-10 Classification of Mental and Behavioral Disorders (Clinical Descriptions and Diagnostic Guidelines)  based clinical interview with emphasis on Depressive disorders (F32.0, F32.1, F32.2, F32.3, F32.8, F32.9), Recurrent depressive disorders (F33.0, F33.1, F33.2, F33.3, F33.4, F33.8, F33.9), dysthymia (F34.1), mixed anxiety and depressive disorder (F41.2), adjustment disorders including pathological grief (F43.20, F42.21, F43.22) was used as the reference standard. ICD-10 was used as the reference standard as it has proven international, standard diagnostic classification utility in general practice and mood disorders research of ICD-10. 
Kiddie-Sads-Present and Lifetime Version (K-SADS-PL)-based psychiatric interview was conducted using the section on Depressive Disorders (dysthymia and major depression) in the Kiddie-Sads-Present and Lifetime Version (K-SADS-PL) with alterations to cover specific ICD-10 Depressive Disorders criteria. 
A consultant pediatrician, followed by a consultant clinical psychologist and finally a consultant psychiatrist, interviewed the adolescents on the same or subsequent week at school. The pediatrician administered the self-rated BDI and assessed the adolescents with CDRS-R. The clinical psychologist independently rated the adolescents with CDRS-R to evaluate the interrater reliability of CDRS-R. The psychiatrist, independently, interviewed the respondents to diagnose the possibility of an ICD-10 category of psychiatric disorder, especially the depressive disorders using a semistructured clinical interview and administered the impact of event scale as well. The semistructured psychiatric interview was conducted using the modified K-SADS-PL. As these three assessments were independently done, the data were also blinded. Twenty percent of the study sample was randomly selected after 4 weeks and reassessed using CDRS-R by the pediatrician to measure the test-retest reliability. The data were collected after the parent provided informed consent and verbal assent of the participants well as the teachers. The local Institutional Review Board reviewed the study protocol and provided approval for the study.
Preliminary checks of skewness verified that our data were suitable for parametric analysis and the psychometric properties of CDRS-R were analyzed at both the item and scale levels. Sensitivity and specificity for various CDRS-R cut-off scores were calculated against the ICD-10 diagnosis of depression in order to determine the optimal diagnostic threshold with receiver operating characteristic (ROC) curve analyses and contingency tables. The interrater and test-retest reliability of CDRS-R was examined with the intraclass correlation. For item consistency, correlation was done between the total CDRS-R score and each item score with Pearson's correlation coefficiet test. Internal consistency was ascertained with Cronbach's α coefficient test. To determine the convergent validity and divergent validity the total CDRS-R score was correlated with total BDI and IES-8 scores respectively with Pearson's correlation coefficient test. The concurrent validity of CDRS-R in the form of criterion validity and discriminant validity, as a clinician-rated measure of depression, was examined by measuring the concordance (overlapping cases) rate and discordance rate. Thus the concordance or discordance of the ICD-10 diagnosis of depression and CDRS-R diagnosis of depression was computed as the quotient of the cases classified as depression by both of the measures applied and the number of cases classified as depression by either of the measure. The construct validity of the CDRS-R was elicited by analyzing its factor structure with principal components analysis and promax rotation. Only factors with eigen values greater than 1 were considered. The CDRS-R items were removed if they failed to load on any factor (loading < 0.50) or had unacceptably high secondary loadings (>0.30).  Data were analyzed using SPSS (version 16).
| ¤ Results|| |
The complete data set was available for all the 181 participants and the mean (sd) age of the adolescents was 15.3(0.4) with a range of 14-17 years. There were more boys (N = 106) than girls (N = 75) in the sample. The mean (sd) BDI score was 13.4(8.2) with a range of 0-42 and CDRS score was 27.5(8.3) with a range of 17-54. In participants identified as having a depressive disorder the clinical diagnoses were mild (N = 2), moderate (N = 2) or severe depression depressive episode with somatic symptoms (N = 1), brief depressive reaction (N = 3), mixed anxiety-depression (N = 2), and grief (N = 1).
The sensitivity and specificity for the various threshold points of the CDRS-R were tested against the reference standard. [Table 1] summarizes these results. A score of ≥30 in CDRS-R achieved a sensitivity of between 83% and specificity of 84% making it appropriate for establishing a diagnosis of depression. The area under curve (AUC) in the ROC for the CDRS-R was 0.87 (95% CI = 0.81-0.91; P=0.0001) [Figure 1].
|Table 1: Specificity and sensitivity of different cut-off scores on the CDRS-R with ICD-10 clinical diagnosis as a reference standard|
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Reproducibility and reliability
The interrater reliability between the pediatrician and clinical psychologists was found to be good (ICC = 0.73; 95% CI = 45 to 88) and the test-retest reliability was also found to be high (ICC = 0.98; 95% CI = 95 to 99). Item consistency analysis was carried out for the CDRS-R scale by correlating item scores with total scale score. The item-total correlation coefficient between each item score and the total CDRS-R score ranged from r = 0.12 to 0.68. Additionally, when we examined the internal consistency of CDRS-R, Cronbach's α coefficient for the whole scale was 0.76 and thus good.
All the major dimensions of depressions were represented in the CDRS-R and none of the 17 items was assigned a score of 0 by more than half of the adolescents with depression in this study suggesting that the content validity was appropriate to their morbid state. The convergent validity between the total CDRS-R and total BDI, calculated with Pearson correlation, was also high (r = 0.71) and significant at the 0.001 level. The divergent validity calculated by correlating the total CDRS-R score with the total IES showed nonsignificant associations (r = 0.28; P = 00.20) demonstrating that the depression construct as measured by CDRS-R diverges from other constructs in psychiatry like post-traumatic stress. There was a moderate concordance rate between the CDRS-R and reference standard of ICD-10 diagnosis (45.45%) in identifying depression among the adolescents. Eleven of the 181 adolescents who received psychiatric assessment fulfilled criteria for depressive disorders and thus more than three-quarter of the patients failed to meet the ICD-10 criteria for depressive disorders. Among the 181 participants, the pediatrician with CDRS-R recognized 29.83% of cases as adolescents with depression and yet, 90.74% of patients labeled as depressed by the pediatrician based on CDRS-R score were not cases of depression according to ICD-10 criteria. It is interesting to note that a large proportion of adolescents were not found to be suffering from any other specific psychiatric disorder by ICD-10 (N = 170) or CDRS-R (N = 127). When we analyzed the divergent validity, among the other disorders noted in the study sample namely the specific learning disorder (N = 2), obsessive compulsive disorder (N = 1), Dhat syndrome (N = 1), tension head ache (N = 1), only 20% of these disorders were also picked as depression by the CDRS-R and 80% were not identified as cases of depression.
The factor structure of CDRS-R showed that the CDRS-R item 2 (difficulty having fun) cross-loaded in to factor 5 and 6, and thus was considered not specific to any domain of depression. Items 5 and 13 (appetite disturbance and suicidal ideation) did not load on to any factor. Otherwise, all items loaded distinctively and without cross-loadings [Table 2]. CDRS-R items 3 (social withdrawal), 10 (low self-esteem), 11 (depressed feelings) loaded on to Factor 1 (Cognitive mood); item 4 (sleep disturbance), item 6 (excessive fatigue), item 7 (physical complaints), item 9 (excessive guilt) loaded on to Factor 2 (Somatic-somatization); item 15 (depressed facial affect), item16 (listless speech), item 17 (hypoactivity) loaded on to Factor 3 (Affective anergia); items 12 (morbid ideations), item 14 (excessive weeping) loaded on to Factor 4 (Cognitive behavioral); item 1 (impaired school work) loaded on to Factor 5 (Impairment) and finally item 8 (irritability) loaded on to Factor 6 (other emotions) [Table 2]. This six-factor structure explained 60.6% of the variance.
|Table 2: Factor loadings of the 17-item six-factor structure of the CDRS-R|
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| ¤ Discussion|| |
The purpose of this study was to validate the clinician-rated Children's Depression Rating Scale-Revised as a scale for identifying adolescent depression in India by pediatricians. Our study showed that the clinician-rated Children's Depression Rating Scale had robust psychometric properties while being used in a primary-care pediatric setting among a primary-care population in this country.
In this study that followed the STARD guidelines for diagnostic accuracy, we suggest a cut-off point ≥30, because this value improved the test's discriminant properties, obtaining a sensitivity of 83% and a specificity of 84%. Using this cut-off point, the mean (sd) total CDRS-R score was 37.67 (7.10) for adolescents with depression and 23.10 (3.18) for those who were not depressed. This cut-off core although is lower than in the original study, similar low threshold score has been described subsequently in another validation study. It is suggested that a CDRS-R total score range of 22-49 is noted among children with clinical depression and a score of greater than 20 warrants a detail assessment of the adolescent for depression. 
The test-retest reliability we have recorded (0.98) is better than that reported (0.86) in the original validation study.  This high test-retest reliability indicates that the temporal stability of the CDRS-R would not be altered by natural mood variations in the adolescent. The interrater reliability in this study was good (0.73) and is low when compared with the original interrater reliability value of 0.86.  However, the good interrater reliability documented in this study is between a clinical psychologist and a pediatrician. This has also been supported by the findings that even raters with little experience administering the CDRS-R can score the instrument in a reliable manner and thus can be reliably used by primary-care pediatricians with limited experience in adolescent mental health issues.  The internal consistency of the CDRS-R was 0.76 and thus this moderate-to-high internal consistency was in accordance with other studies reported. 
The face and content validity of CDRS-R were found appropriate for the disorder of depression among adolescents in the Indian culture because of the inclusion of the various symptom clusters that represent the construct of depression as well as the lack of redundancy of its items. With regard to concurrent validity, the CDRS-R showed a high convergent validity as noted by its strong positive correlation (r = 0.71) with the BDI scale for adolescents. In past studies also CDRS-R demonstrated moderate to high correlations with the Hamilton Rating Scale for Depression and several self-rated depression scales as well as diagnostic interviews. , In our study, CDRS-R showed a high divergent validity by its strong negative correlation (r = 0.28) with the IES-8 for adolescents. In the past discriminant validity had been recorded as low because the CDRS-R has difficulty distinguishing between depression and anxiety and overestimates depression severity in children with general medical conditions due to its emphasis on somatic symptoms.  In this study, CDRS-R showed a moderate concordance rate with ICD-10 diagnostic criteria for depressive disorders that is less than the concordance shown in the original validation study where CDRS-R scores show good concordance with research diagnostic criteria (RDC) diagnoses of depression.  This could be also because of using a stringent research diagnostic criteria (RDC) and a clinical diagnostic criteria (ICD-10) in the original and current study respectively as reference standard. We analyzed the scale's discriminant validity between adolescents with and without depression and controls by means of the diagnostic performance of ROC curve. The area under the curve was 0.87 (95% CI = 0.81 to 0.91; P=0.0001) which, being close to 1, indicates a good discriminant capacity. Also, the discriminant capacity study indicates that a score ≥30 obtains the best balance between sensitivity and specificity. This score also discriminated 80% of psychiatric disorders other than depression demonstrating it discriminating ability.
Our study extracted a six-factor structure explaining 60.6% of the variance. A four-factor structure explaining 54% of the variance  and a five-factor structure consisting of observed depressive mood, anhedonia, morbid thoughts, somatic symptoms, and reported depressive mood has been reported in the literature.  However, as the studies have used different criteria for model fit (Kaiser criteria, Thurston's criteria, eigen value, scree plots), those results are difficult to compare with our results.
The results of this study need to be considered in light of the following limitations. First, our sample is unlikely to be representative of the general pediatric population as the study was based on school population. Secondly, the low prevalence of depression in the sample could have limited the power and stability of the sensitivity analyses. Thirdly, we opted for convenience sampling in order to improve participation rate. As a result, there was an over-representation of boys. Finally, in this study we have documented a single diagnostic score and additional studies are needed to improve score interpretation to diagnose depressive disorders of different severity in clinical practice.
In conclusion, the Children's Depression Rating Scale-Revised showed strong psychometric properties and it is now available to be used in the primary-care pediatric practice. Unlike self-reported inventories for depression, the CDRS-R not only assesses depression, but also takes the first step in the therapeutic process by bringing the adolescent into positive contact and interaction. From a public health standpoint, identifying early clinical features of depression makes it possible to provide early interventions that could prevent or reduce the impact of depressive disorders among adolescents.
| ¤ Acknowledgement|| |
We thank the students, schools and their families for their assistance and observations.
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[Table 1], [Table 2]