Convergent and divergent validity of the schedule for affective disorders and schizophrenia for school-age children - present and lifetime version diagnoses in a sample of children and adolescents with obsessive-compulsive disorder.

The presence of comorbid conditions associated with paediatric obsessive-compulsive disorder (OCD) is reported to range from 50 to 80% and to have an impact on treatment outcome. Accurate identification of comorbid psychiatric disorders is necessary in order to provide personalised care. Reliable and valid diagnostic interviews are essential in the process of establishing the correct diagnoses. The objective of this study was to evaluate the convergent and divergent validity of four diagnose categories generated by the Schedule for Affective Disorders and Schizophrenia for School-Age Children - Present and Lifetime Version (K-SADS-PL). The diagnose categories were: anxiety, depression, attention deficit hyperactivity disorder (ADHD), and oppositional defiant disorder (ODD). The K-SADS-PL was applied in a clinical sample of youth aged 7-17 years (N = 269), who were participants in the Nordic long-term OCD-treatment study (NordLOTS). Youth and parents completed measures to evaluate symptoms of anxiety, depression, ADHD, and ODD. Convergent and divergent validity of K-SADS-PL anxiety diagnosis was supported based on both anxiety self- and parent-reports. Similarly, support was found for convergent and divergent validity of ADHD and ODD diagnoses. For depressive disorder, support for convergent validity was found based on the depression self-report. Support for divergent validity of depression was found based on both the depression self- and parent-reports. Results of the present study suggest that the K-SADS-PL generates valid diagnoses of comorbid anxiety disorders, depression disorders, ODD, and ADHD in children and adolescents with OCD.