A meta-analysis of clonidine for symptoms of attention-deficit hyperactivity disorder.

OBJECTIVE Meta-analysis was used to review the literature on the clinical use of clonidine to treat symptoms of attention-deficit hyperactivity disorder (ADHD). METHOD A review of the literature from 1980 to 1999 revealed 39 studies that reported clonidine's efficacy and side effects for symptoms of ADHD and comorbid conditions. Of these, 11 reports provided sufficient information to be included in a meta-analysis. RESULTS Meta-analysis using weighted variables revealed clonidine demonstrates a moderate effect size of 0.58 +/- 0.16 (95% confidence interval = 0.27-0.89) on symptoms of ADHD in children and adolescents with ADHD and ADHD comorbid with conduct disorder, developmental delay, and tic disorders. CONCLUSIONS Clonidine may be an effective second-tier treatment for symptoms of ADHD, but it has an effect size less than that of stimulants. Clinical use of clonidine is associated with many side effects.