Evaluation and comparison of psychometric instruments for pediatric bipolar spectrum disorders in four age groups

The primary objective of this study was to evaluate the psychometric characteristics of the Young Mania Rating Scale (YMRS), the K-SADS Mania Rating Scale (KMRS), and the Children's Depression Rating Scale-Revised (CDRS-R) across four age groups (4-7, 8-10, 11-13, and 14-17 years). The interrater reliability of K-SADS diagnoses was also examined. Participants included 1,014 youths (62.1% male) presenting to an outpatient clinical research center. Diagnoses were based upon semistructured K-SADS interviews. Symptomatic assessments and ratings of psychosocial functioning were completed following the diagnostic interview. Mania measures showed unifactorial structure and good internal consistency reliability (alpha = 0.79-0.95) across all ages groups. The CDRS-R factor structure shifted from one to two factors in adolescents. For all ages and symptom measures, reliability was excellent in the range where differential diagnosis is most difficult. Efficiencies in discriminating bipolar spectrum disorders from other disorders were excellent (areas under the curve, AUCs = 0.92-0.99) for mania measures, with comparable discrimination across age groups. Interrater reliability of K-SADS diagnoses was excellent across age groups (smallest kappa = 0.95). Results indicate that mania measures are useful for assessing symptoms across a wide range of ages. The CDRS-R may be better conceptualized as a two-factor measure in older adolescents. The semistructured K-SADS interview can be used to generate reliable diagnoses across a broad age range.