Identifying comorbid depression and disruptive behavior disorders: comparison of two approaches used in adolescent studies.

Interest in commonly co-occurring depression and disruptive behavior disorders in children has yielded a small body of research that estimates the prevalence of this comorbid condition and compares children with the comorbid condition and children with depression or disruptive behavior disorders alone with respect to antecedents and outcomes. Prior studies have used one of two different approaches to measure comorbid disorders: (1) meeting criteria for two DSM or ICD diagnoses or (2) scoring .5 SD above the mean or higher on two dimensional scales. This study compares two snapshots of comorbidity taken simultaneously in the same sample with each of the measurement approaches. The Developmental Pathways Project administered structured diagnostic interviews as well as dimensional scales to a community-based sample of 521 11-12 year olds to assess depression and disruptive behavior disorders. Clinical caseness indicators of children identified as "comorbid" by each method were examined concurrently and 3-years later. Cross-classification of adolescents via the two approaches revealed low agreement. When other indicators of caseness, including functional impairment, need for services, and clinical elevations on other symptom scales were examined, adolescents identified as comorbid via dimensional scales only were similar to those who were identified as comorbid via DSM-IV diagnostic criteria. Findings suggest that when relying solely on DSM diagnostic criteria for comorbid depression and disruptive behavior disorders, many adolescents with significant impairment will be overlooked. Findings also suggest that lower dimensional scale thresholds can be set when comorbid conditions, rather than single forms of psychopathology, are being identified.