Convergent and divergent validity of K-SADS-PL diagnoses in a clinical 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. Hence, the accurate identification of comorbid psychiatric disorders in children and adolescents with OCD is necessary in order to provide adequate treatment. Reliable and valid diagnostic interviews are important in the process of accurately identifying psychiatric problems. The objective of this study was to evaluate the convergent and divergent validity of anxiety, depression, attention deficit hyperactivity disorder (ADHD), and oppositional defiant disorder (ODD) diagnoses generated by the Schedule for Affective Disorders and Schizophrenia for School-Age Children - Present and Lifetime Version (K-SADS-PL) in a clinical sample of youth aged 7-17 years (N=269), all of whom are participating in the Nordic long-term OCD-treatment study (NordLOTS). In addition, the children and their parents reported anxiety symptoms using the Screen for Child Anxiety Related Disorders (SCARED), and depression symptoms with the Mood and Feelings Questionnaire (MFQ). Parents also reported symptoms of ODD and ADHD with the Child Behaviour Checklist (CBCL). Convergent and divergent validity of K-SADS-PL anxiety diagnosis was supported based on both SCARED self- and parent-reports. Similarly, we found support for convergent and divergent validity of ADHD and ODD diagnoses based on CBCL reports. For depressive disorder, we found support for convergent validity based on the MFQ self-report but not on the MFQ parent-report. Support was found for divergent validity based on both the MFQ self- and parent-reports. The K-SADS-PL generates valid diagnoses of comorbid anxiety disorders, depression disorders, ODD, and ADHD in children and adolescents with OCD. Keywords: Convergent validity, divergent validity, K-SADS-PL, paediatric OCD, comorbidity