Differences in the Clinical Characteristics of Remission and Non-Remission Groups with Once-Daily OROS-Methylphenidate Treatment of Attention-Deficit/Hyperactivity Disorder

Objective：Attention-deficit/hyperactivity disorder (ADHD) is a common, life-long condition associated with major functional impairment, and remission is the primary goal of treatment. The purpose of this study was to identify differences in the clinical characteristics of remission and non-remission groups composed of Korean children and adolescents with ADHD. Methods：Fifty-nine children and adolescents, 6-15 years old, diagnosed with ADHD according to the Diagnostic and Statistical Manual-IV (DSM-IV) criteria were included in the study. The study design was an 8-week, open-label trial of OROSmethylphenidate(OROS-MPH) monotherapy. The subjects were assessed using the Korean ADHD Rating Scale (K-ARS), Clinical Global Impression of Severity (CGI-S), Clinical Global Impression of Improvement (CGI-I), and Barkley Side Effect Rating Scale at baseline and 1, 2, 4, and 8 weeks after starting OROS-MPH treatment. Remission was defined as both a score of ≤2 on the CGI-S and a score of ≤18 on the K-ARS at the eighth week of the trial, when we examined the differences in the clinical characteristics between the remission and non-remission groups. Results：The remission rate at the eighth week was 47.5% (n=28). No differences were observed in the age, sex, weight, severity of symptoms reported by the parent, comorbidities at baseline, or doses of OROS-MPH at each evaluation point between the remission and non-remission groups. However, the non-remission group had higher scores in the CGI-S at baseline than the remission group. A difference in symptom improvement between the two groups began at the first week of the trial, and the remission group was less likely to have side effects at the eighth week. Conclusion：The results suggest that individual biological diversity may mediate different treatment responses to OROS-MPH. Interventions other than medication are needed to achieve remission and to restore proper functioning of patients with ADHD in the nonremission group.