Assessment of Diagnosis Timing of Attention-Deficit/Hyperactivity Disorder in Working-Age Workers with Psychiatric Diseases Using Large Claims Data

Attention deficit/hyperactivity disorder (ADHD) is a common developmental disorder. This study aims to clarify the timing of diagnosis of ADHD in working-age workers with psychiatric comorbidities using large claims data in Japan. Based on a literature survey, we identified 10 typical comorbidities of ADHD. Among 3064162 participants with social insurance, 215060 working-age workers who were diagnosed with the 10 typical comorbidities of ADHD were included. Cohort 1 consisted of 96994 patients with the index date set as the earliest date of diagnosis of a comorbidity within the 12-month screening and 12-month observation periods. In cohort 2, 107436 patients were included, and the first date of diagnosis of each comorbidity was used as the index month. In cohort 1, 0.19% of the patients were diagnosed with ADHD after being diagnosed with a typical comorbidity. In cohort 2, 4 out of 4 patients with ADHD and obsessive-compulsive disorders were diagnosis ADHD after obsessive-compulsive disorders. Pervasive developmental disorders were the highest comorbidity of ADHD for 62 out of 566 (11.0%) patients. This is the first study to determine the proportion of ADHD with typical comorbidities in working-age workers in Japan. Our findings highlight the need for timely diagnosis of ADHD to improve patients' QOL.