Objective: To compare the safety and efficacy of atomoxetine, a selective inhibitor of the norepinephrine transporter, versus placebo in Attention-Deficit/Hyperactivity Disorder (ADHD) patients with comorbid Oppositional Defiant Disorder (ODD).
Methods: A subset analysis of 98 children from two identical, multi-site, double-blind, randomized, placebo-controlled trials involving 9 weeks of treatment with atomoxetine or placebo was conducted. Patients met DSM-IV ADHD criteria. ODD was diagnosed with the Diagnostic Interview for Children and Adolescents-IV (DICA-IV; Reich, Weiner, and Herjanic, 1997). ADHD severity was assessed with the ADHD Rating Scale-IV-Parent Version: Investigator Administered and Scored (ADHD-RS-IV-Parent:lnv; DuPaul, Power, Anastopoulos, and Reid, 1998); the short version of the Conners' Parent Rating Scales-Revised (CPRS-R:S; Conners, 2000); and the Clinical Global Impressions of ADHD Severity (CGI-ADHD-S; Guy, 1976). Clinical response was defined as a > or = 25% reduction in ADHD-RS-IV-Parent:lnv total score.
Results: ADHD-RS-IV-Parent:lnv, CGI-ADHD-S, and three CPRS-R:S subscale scores improved markedly with atomoxetine treatment. However, a decrease in the CPRS-R:S Oppositional subscore for atomoxetine-treated patients was not significantly greater than scores for placebo-treated patients. Clinical response rates were 65.4% in the atomoxetine group, and 36.4% in the placebo group (p = .007).
Conclusion: Atomoxetine was effective for the treatment of ADHD in patients with comorbid ODD. It did not significantly reduce the severity of ODD symptoms, and was well tolerated by the patients.