Quetiapine addition in obsessive-compulsive disorder: is treatment outcome affected by type and dose of serotonin reuptake inhibitors?

Background: The purpose of this study was to assess the effect of type and dose of serotonin reuptake inhibitors (SRIs) on treatment outcome in quetiapine addition trials for obsessive-compulsive disorder.

Methods: Results from all available, double blind, placebo-controlled quetiapine addition trials were pooled. Treatment outcome was assessed in a sample of 102 patients by change from baseline to end point on the Yale-Brown obsessive-compulsive scale (Y-BOCS).

Results: Quetiapine addition was superior with a mean Y-BOCS decrease of 6.8 +/- 6.7 compared with placebo with a decrease of 3.9 +/- 6.5 points. Patients with the lowest SRI dose showed the largest decrease on the Y-BOCS (11.6 +/- 7.7) compared with patients with the median dose (6.1 +/- 6.1) and highest dose (5.9 +/- 6.4).

Conclusions: We found a superior response in the quetiapine addition group compared with the placebo group. The best response was achieved with the combination of clomipramine, fluoxetine, and fluvoxamine and with the lowest SRI doses.