Quetiapine augments the effect of citalopram in non-refractory obsessive-compulsive disorder: a randomized, double-blind, placebo-controlled study of 76 patients

OBJECTIVE: To assess the efficacy of quetiapine addition to citalopram in treatment-naive or medication-free obsessive-compulsive disorder (OCD) patients. METHOD: Seventy-six patients who met DSM-IV criteria for OCD and who were drug-free or drug-naive at entry were randomly assigned in a 10-week, double-blind trial with citalopram (60 mg/day) plus quetiapine (300-450 mg/day) or placebo; treatment-refractory OCD patients were excluded. Of the 76 eligible patients, 66 patients completed the trial-31 in the quetiapine and 35 in the placebo group. The change from baseline to endpoint on the total Yale-Brown Obsessive Compulsive Scale (YBOCS) and the response to treatment in the quetiapine addition compared with the placebo addition group were the primary outcome measures. Response was defined as a 35% or greater reduction on the YBOCS and a Clinical Global Impressions-Improvement (CGI-I) score at endpoint of 1 or 2. The study was conducted from November 2003 to June 2005 at the University Medical Centre Utrecht, The Netherlands. RESULTS: As measured by the mean reduction in YBOCS scores following an intent-to-treat, last-observation-carried-forward analysis, quetiapine addition (11.9) was significantly superior to placebo (7.8; p = .009). Quetiapine addition was also significantly superior to placebo on the CGI-I scale, with a mean +/- SD CGI-I score of 2.1 +/- 1.3 versus 1.4 +/- 1.2, respectively (p = .023). Quetiapine addition (N = 22, 69%) was also associated with a significantly greater number of patients responding to treatment compared with placebo addition (N = 15, 41%; p = .019). More patients receiving quetiapine (N = 8) than placebo (N = 2; NS) discontinued treatment due to adverse events. CONCLUSIONS: The combination of quetiapine and citalopram was more effective than citalopram alone in reducing OCD symptoms in treatment-naive or medication-free OCD patients. TRIAL REGISTRATION: www.trialregister.nl Identifier NTR116