Comorbid oppositional defiant disorder and the risk of relapse during 9 months of atomoxetine treatment for attention- deficit/hyperactivity disorder

Objective To examine the influence of comorbid oppositional defiant disorder (ODD) on the relative risk (RR) of relapse during 9 months of treatment with atomoxetine for attention-deficit/ hyperactivity disorder (ADHD). Method Four hundred and sixteen children and adolescents with ADHD whose symptoms remitted during initial 10-week, open-label atomoxetine treatment were randomly assigned to continue with atomoxetine or placebo. Results In all, 43 % met criteria for comorbid ODD. A total of 17% of patients with comorbid ODD relapsed (CGI-Severity score ≥ 3 and ADHD Rating Scale total score of 90 % or more of baseline at study entry on two consecutive visits) during atomoxetine treatment, compared with 26 % of patients without comorbid ODD (RR 0.67,95% CI 0.42-1.06). Mean time to relapse was not significantly different [mean (SE) days to relapse, ADHD/ +ODD: 215 (7.38);ADHD/-ODD: 211 (7.61); log rankp=0.08]. This finding is placed within the context of atomoxetine affording an overall protection against relapse compared with placebo (RR 0.59, 95% CI 0.43-0.80). Conclusions Comorbid ODD does not influence the rate of relapse of patients with ADHD during longer-term treatment with atomoxetine. Atomoxetine protects against the relapse of ADHD symptoms regardless of the presence or absence of comorbid ODD.