Psychometrics of rating scales for externalizing disorders in Japanese outpatients: The ADHD-Rating Scale-5 and the Disruptive Behavior Disorders Rating Scale

ObjectivesThis study validated the Japanese version of the Attention-Deficit/Hyperactivity Disorder-Rating Scale-5 (ADHD-RS-5) and the Disruptive Behavior Disorders Rating Scale. We extended the ADHD-RS-5 by adding the oppositional defiant disorder and conduct disorder subscales to compare the two rating scales psychometrically.MethodsWe examined the internal consistency, test-retest reliability, construct validity and criterion validity of the two rating scales in 135 Japanese outpatients aged 6-18 years.ResultsThe internal consistency and test-retest reliability were good for all the subscales of the two rating scales except for the conduct disorder subscale of the ADHD-RS-5 extended. Good construct validity was revealed by expected correlational patterns between subscales from the two rating scales and the Children Behavior Checklist. The criterion validity was good for all the subscales of the two rating scales rated by parents, while teacher-ratings revealed substantially lower predictive ability for all the subscales. Agreement between parent- and teacher-ratings of the two rating scales was generally moderate and using predictive ratings alone of both ratings showed the best predictive ability among the integration methods examined.ConclusionThe two rating scales have sound psychometric properties and will aid in screening and severity assessment of externalizing disorders in Japanese clinical settings.