Comparison of Persistence and Adherence Between Adults Diagnosed with Attention Deficit/Hyperactivity Disorder in Childhood and Adulthood

PURPOSE: Long-term treatment of attention deficit/hyperactivity disorder (ADHD) is important, but adherence and persistence in practice are still suboptimal. To better understand medication compliance for ADHD, we divided adults with ADHD into groups based on their history of childhood and adolescent ADHD, and compared their characteristics, medication adherence and persistence, and associated factors. PATIENTS AND METHODS: This study included participants aged 18–23 years with claims related to ADHD (International Classifications of Diseases 10th edition, F90.0x) and anti-ADHD medication from July 1, 2017 to December 31, 2018, and with a history of any F90.0x claim(s) from January 1, 2007 to June 30, 2017 in the Korean National Health Insurance System Claims database. Participants were divided into those diagnosed with ADHD in childhood and adulthood. Persistence with or without a 30-day gap and adherence according to a medication possession ratio (MPR) >80% were calculated. RESULTS: There were 10,604 patients included in the study. Adults with a childhood diagnosis of ADHD showed significant male predominance, more use of National Health Insurance, and were more often treated by psychiatrists and in hospitals than those with an adulthood diagnosis. Combination therapy was the most common initial treatment in those with an adulthood diagnosis, while monotherapy with Concerta was most common in those with a childhood diagnosis. Both groups had over 60% of participants with an MPR >80% and over 50% with persistence without a 30-day gap. Treatment in a private clinic and initial monotherapy with bupropion were found to be significantly associated with adherence in both groups. CONCLUSION: The significant differences found between these groups add evidence to suggest that adult with ADHD diagnosed in adulthood may be a separate entity from those in childhood. A thorough evaluation at diagnosis and treatment in private clinics may improve medication compliance in this population.