Side effects as predictors of drug response in obsessive-compulsive disorder

Differences between the side effect profiles of clomipramine (CMI) and the selective serotonin reuptake inhibitors may be important factors in both tr eatment outcome and patient selection in obsessive-compulsive disorder (OCD ). Safety and efficacy data from an industry-sponsored, multicenter clinica l trial of CMI were analyzed previously using tabular and multiple regressi on methods. Good response, defined as at least a 35% drop in final scores o n the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), was associated with a later age of OCD onset and certain early side effects that may reflect a s ensitivity of responders to CMI's serotonergic actions. The authors conduct ed a similar analysis of data from an industry-sponsored clinical trial of fluoxetine in OCD. Fluoxetine response did not seem to be associated with a ge of OCD onset. Good response to both drugs was associated with initial ne rvousness and sexual complaints. The common side effects of fluoxetine (hea dache, nausea, and gastrointestinal complaints) did not seem to be associat ed with treatment response. Slight differences in the protocols of the two clinical trials yielded patient populations that were different in factors found to be associated with treatment outcome: subjects in the fluoxetine s tudy had lower scores on the Y-BOCS, higher scores on the Hamilton Rating S cale for Depression, and an earlier age of OCD onset.