Clinical trials performed for FDA registration for OCD in youth typically excluded youth with comorbid conditions. Notably, many young people have both OCD and Tourette syndrome or OCD and ADHD. The efficacy and effectiveness of SSRIs in real affected clinical populations was generally not been studied and the generalizability of randomized controlled trials to all youth with OCD was unknown.
This study, led by Drs. Geller, Biederman, and Coffey, addressed treatment of young people with both OCD and Tourette syndrome using paroxetine (a selective serotonin reuptake inhibitor, or SSRI; brand name “Paxil”), clomipramine (a tricyclic antidepressant), and both. Clomipramine has shown usefulness for tic disorders given its noradrenergic effects, and the study wanted to understand whether combining clomipramine with an SSRI would be useful for treating comorbid OCD and Tourette syndrome. The study evaluated 193 subjects treated with paroxetine with comorbid conditions compared to 142 with OCD but no comorbid disorders. Although the response to paroxetine in the overall group was high (71%) the response for those with comorbid ADHD (56%) tic disorders (53%) and oppositional defiant disorder (39%) was significantly lower than those youth with OCD only (75%). In addition, the relapse rate of OCD following medication discontinuation was significantly higher in those youth with one or more comorbid disorders compared to youth with no comorbid disorders.
Geller D.A., Biederman, J., Stewart, S.E., Mullin, B., Farrell, C., Wagner, K.D., Emslie, G., & Carpenter, D. (2003). Impact of comorbidity on treatment response to paroxetine in pediatric obsessive-compulsive disorder: Is the use of exclusion criteria empirically supported in randomized clinical trials? Journal of Child and Adolescent Psychopharmacology, 13, S19-29. doi: 10.1089/104454603322126313.