What is already known on this topic?

For adult patients with obsessive-compulsive disorder (OCD) resistant to serotonin reuptake inhibitors (SRIs), American Psychological Association practice guidelines1 recommend adding either behavioural therapy based on exposure and response prevention (EX/RP) or a second-generation antipsychotic. Factors mentioned in the guidelines1 that might lead patients and clinicians to prefer the antipsychotic option includes local availability of properly trained cognitive-behavioural therapy (CBT) therapists, treatment costs and the patient's ability to comply with CBT (willingness to do the time-intensive and emotionally challenging work of CBT over several weeks). Among antipsychotics, risperidone has been most effective in small trials.2–4

What this paper adds?

• This first large-scale (100 patients) comparison of the two augmentation strategies yielded far superior efficacy in symptom reduction, remission and other metrics for EX/RP than for risperidone.

• Risperidone was only slightly (but not significantly) more effective than placebo.

• Adverse effects of 12-week SRI treatment were also observed in overall 37% of patients at baseline, which is more than expected.

Limitations

• Successful augmentation (EX/RP) produced a small (25%) improvement in 80% of patients, however, only 43% achieved ‘minimal’ symptoms, meaning most patients were still partial responders even after augmentation.

• Maximum permitted dose of risperidone was 4 mg/day, …