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 >or= 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 rank p = 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.