A 2014 meta-analysis by Veale et al3 included double-blind, randomized trials that examined atypical antipsychotics compared with placebo for adults with OCD that used an intention-to-treat analysis. Unlike the Cochrane Review, these studies used the Y-BOCS as a primary outcome measure. Participants had a Y-BOCS score of ≥16; had at least 1 appropriate trial of an SSRI or clomipramine (defined as the maximum dose tolerated for at least 8 weeks); and had to continue taking the SSRI or clomipramine throughout the trial, which was a duration of at least 4 weeks. Of 46 published antipsychotic papers that were identified, 20 were excluded and 12 were duplicates. The primary reason for trial exclusion was open-label study design.
Fourteen articles were included in the meta-analysis, but all had small sample sizes and no long-term follow-up data.3 Antipsychotics in the meta-analysis included risperidone (4 studies), quetiapine (5 studies), olanzapine (2 studies), aripiprazole (2 studies), and paliperidone (1 study).
The overall difference in Y-BOCS score change between drug and placebo groups was 2.34 points, which had an overall effect size of d = 0.40. Those taking antipsychotics had approximately a 10% reduction in Y-BOCS score over time. The overall difference was statistically significant with risperidone (overall mean reduction of 3.89 points on the Y-BOCS; 95% CI 1.43 to 5.48; effect size of d = 0.53) and aripiprazole (difference in Y-BOCS outcome 0.1 scores of 6.29 points; effect size of d = 1.11). One trial of risperidone used a low dose (0.5 mg) and had a larger effect size than the studies that used moderate doses. The overall difference was not statistically significant for quetiapine (difference of Y-BOCS outcome scores of 0.81 points) or olanzapine (difference in Y-BOCS outcome scores of −0.19; indicating <1 point difference on the Y-BOCS).3
Studies included in the meta-analysis ranged in durations from 6 to 16 weeks; duration of ≥4 weeks did not make a difference in response. One study demonstrated a worsening of symptoms in the quetiapine group between weeks 4 and 12. Only 4 studies included most patients that had a previous trial of CBT. One study with an additional treatment arm evaluating CBT found that adding CBT was superior to adjunctive risperidone or placebo. Another study found that adding clomipramine or placebo to fluoxetine was superior to treatment with quetiapine. All study participants had Y-BOCS scores that indicated moderate OCD severity (16 to 23). Those with higher baseline Y-BOCS scores had a larger effect size for risperidone and quetiapine.3
Two studies included in the meta-analysis classified OCD symptoms by subtype, such as by dimensions of checking; symmetry, ordering, counting, and repeating; contamination and cleaning; and hoarding. Currently, no clinically significant predictor of outcome of antipsychotic therapy has been identified. Two studies included in the meta-analysis assessed patients with comorbid tic disorders and found no difference by treatment. One study demonstrated benefit of haloperidol in patients with comorbid tic disorders compared with those without comorbid tic disorders. Of note, none of the studies included in the meta-analysis excluded patients with hoarding characteristics, which generally indicate a worse prognosis with treatment.3
In 2015, Dold et al6 provided an update to a 2013 meta-analysis7 assessing antipsychotic augmentation of SSRIs in treatment-resistant OCD. This update included 2 new RCTs. The 2013 analysis7 concluded that risperidone should be considered first-line and is preferred over olanzapine and quetiapine. However, the update found the highest effect size for aripiprazole (d = −1.35), followed by haloperidol (d = −0.82), risperidone (d = −0.59), quetiapine (d = −0.50), olanzapine (d = −0.49), and paliperidone (d = −0.21).6,7
The 2015 update6 concluded that the antipsychotic doses used in trials were moderate and that there was no association between dose and treatment response, indicating that high doses of antipsychotics may not be more effective. Dold et al6 postulated that the antipsychotic doses required for treating OCD are similar to those used in treating major depressive disorder and lower than doses used in treating schizophrenia. The 2013 meta-analysis demonstrated that moderate doses of antipsychotics resulted in statistically significant efficacy (relative risk [RR] = 3.99, 95% CI 1.92 to 8.27), while low doses did not demonstrate statistical significance (RR = 1.06, 95% CI 0.45 to 2.53).6,7
The 2015 subgroup analysis update evaluated the duration of SSRI treatment prior to the antipsychotic augmentation phase, but did not demonstrate statistically significant efficacy for studies with <8 weeks’ duration of SSRI treatment, further highlighting the need for extended duration of treatment with an SSRI prior to augmentation.6
The 2013 meta-analysis discussed populations with comorbid tic disorders, including a study that found that patients with OCD and comorbid tic disorders benefit more from adjunctive antipsychotic therapy than those without the comorbidity. The 2015 update excluded trials that included patients with comorbid tic disorders to reduce bias, which did not affect the overall effect sizes of the data.6,7
In summary, efficacy has been demonstrated for risperidone and aripiprazole. There has been no benefit demonstrated with olanzapine and limited benefit with quetiapine. One study suggested worsening of symptoms with quetiapine the longer that treatment persisted.3,5-7