Psychometric properties of the Japanese ADHD-RS in preschool children

•The Japanese ADHD-RS had confirmed factor structures and showed good reliability.•Japanese preschoolers scored significantly lower in the ADHD-RS than US children.•P-ADHD-RS had high sensitivity and specificity, and moderate PPV in 90th percentile. Children with ADHD show multiple difficulties in their lives. Its early detection is important to provide timely intervention. To evaluate the psychometric properties of the Japanese version of the home and school form of the ADHD-Rating Scale-IV (P- and T-ADHD-RS) for screening five-year-olds with ADHD. The parents and teachers of 838 children (452 boys, 386 girls; including 28 boys, 18 girls diagnosed ADHD) completed the ADHD-RS and the Strengths and Difficulties Questionnaire in a community health check-up. The P- and T-ADHD-RS confirmed the two-factor model (Inattention and Hyperactivity-Impulsivity) and internal consistencies (CFI=0.968, 980; RMSEA=0.049, 0.055; SRMR=0.030, 0.024; α=0.86–.93). Japanese boys and girls scored significantly lower in all scales of the P- and T-ADHD-RS (d=0.65–1.14, 0.36–0.59) than US children. The P-ADHD-RS showed higher accuracy in area under the curve (AUC), sensitivity, and positive predictive value (PPV) than the T-ADHD-RS (AUC=0.955, 0.692; sensitivity=89.13%, 30.23%; PPV=46.59%, 16.05%). The P-ADHD-RS shows good reliability and validity for screening children with possible ADHD in a community. Longitudinal studies are needed to examine its predictive validity of adaptation in their lives at school.