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We sought to determine differences in efficacy and tolerability between different doses of selective serotonin reuptake inhibitors in the treatment of obsessive-compulsive disorder (OCD) using meta-analysis. We identified 9 studies involving 2268 subjects that were randomized, double-blind placebo-controlled clinical trials that compared multiple, fixeddoses of selective serotonin reuptake inhibitors (SSRIs) to each other and to placebo in the treatment of adults with OCD. Change in Y-BOCS score, proportion of treatment responders, and dropouts (all-cause and due to side-effects) were determined for each included study. Weighted mean difference was used to examine mean change in Y-BOCS score. Pooled absolute risk difference was used to examine dichotomous outcomes. Meta-analysis was performed using a fixed effects model in RevMan 4.2.8. We found that compared with either low or medium doses, higher doses of SSRIs were associated with improved treatment efficacy, using either Y-BOCS score or proportion of treatment responders as an outcome. Dose of SSRIs was not associated with the number of all-cause dropouts. Higher doses of SSRIs were associated with significantly higher proportion of dropouts due to side-effects. These results suggests that higher doses of SSRIs are associated with greater efficacy in the treatment of OCD. This SSRI efficacy pattern stands in contrast to other psychiatric disorders like Major Depressive Disorder. This greater treatment efficacy is somewhat counterbalanced by the greater side-effect burden with higher doses of SSRIs. At present, there are insufficient data to generalize these findings to children or adolescents with OCD.

Background Individual randomized controlled trials (RCTs) have demonstrated the efficacy of cognitive behavioral therapy (CBT) and serotonin reuptake inhibitors (SRIs) for the treatment of youth with obsessive-compulsive disorder (OCD). While meta-analyses have confirmed these results, there has been minimal examination of treatment moderators or an examination of treatment response and symptom/diagnostic remission for these two treatment types. The present report examined the treatment efficacy, treatment response, and symptom/diagnostic remission for youth with OCD receiving either CBT or SRIs relative to comparison conditions, and examined treatment moderators. Method A comprehensive literature search identified 20 RCTs that met inclusion criteria, and produced a sample size of 507 CBT participants and 789 SRI participants. Results Random effects meta-analyses of CBT trials found large treatment effects for treatment efficacy (g=1.21), treatment response [relative risk (RR)=3.93], and symptom/diagnostic remission (RR=5.40). Greater co-occurring anxiety disorders, therapeutic contact, and lower treatment attrition were associated with greater CBT effects. The number needed to treat (NNT) was three for treatment response and symptom/diagnostic remission. Random effects meta-analyses of SRI trials found a moderate treatment effect for treatment efficacy (g=0.50), treatment response (RR=1.80), and symptom/diagnostic remission (RR=2.06). Greater methodological quality was associated with a lower treatment response for SRI trials. The NNT was five for treatment response and symptom/diagnostic remission. Conclusions Findings demonstrate the treatment effects for CBT and SRIs across three important outcome metrics, and provide evidence for moderators of CBT across trials.