Safety
Assessing potential harms related to the use of antipsychotics in treating OCD is complicated, because this information is not always assessed in trials. Instead, researchers often focus on exploring potential benefits because long-term effects of antipsychotics, including sedation, weight gain, metabolic syndrome, and extrapyramidal side effects, are well documented.3
Trials included in the meta-analysis by Veale et al3 had a maximum duration of 16 weeks, so it is likely that many of the potential harms of antipsychotic use would not yet have been measurable. The authors cautioned that, although aripiprazole and risperidone demonstrated benefit, their benefit must be weighed against the potential physical risks of long-term antipsychotic use.3One study that was not included in the meta-analysis by Veale et al3 evaluated individuals who did not respond to a SSRI, and randomly assigned them to quetiapine, olanzapine, or risperidone plus CBT. At 1-year follow-up, 50% of participants receiving an antipsychotic had an increase of >10% in body mass index (BMI) and had higher fasting blood sugars compared with only 15.2% of participants with increased BMI in the comparison group (SSRI responders).3
Foa et al8 investigated long-term outcomes (ie, 6 months) of SSRI augmentation with ERP or risperidone in patients with OCD. Forty patients were randomized to receive risperidone, and 9 were considered responders. Only 8 chose to enter the maintenance phase, and of those participants, 5 did not complete the study. Two withdrew due to worsening depression, 2 withdrew due to intolerable adverse effects, and 1 was lost to follow-up. Unfortunately, there was no further discussion of what the intolerable adverse effects were.8
Patients with comorbid schizophrenia and OCD face additional risks. Lifetime prevalence rates of OCD are greater in persons with schizophrenia compared with the general population (26% vs 8%, respectively). Most studies have demonstrated poor prognosis and medication adherence among patients with comorbid schizophrenia and OCD. Fonseka et al9 assessed the risk of antipsychotic induction and exacerbation of OCD symptoms in patients with schizophrenia. Induction and exacerbation of OCD symptoms with clozapine was evident in several case reports, series, and retrospective reviews. A dose-dependent relationship is demonstrated in the literature as well. It is thought that this risk is related to clozapine’s action at the 5-HT2 receptor. Although evidence is limited, it appears that compared with other antipsychotics, clozapine is associated with the greatest risk of induction and exacerbation of OCD symptoms, with 20% to 28% of clozapine-treated patients exhibiting induction of OCD symptoms and 10% to 18% exhibiting an exacerbation of existing OCD symptoms.
Evidence of olanzapine induction and exacerbation of OCD symptoms is also limited to case reports and retrospective studies. However, some studies have estimated induction of OCD symptoms with olanzapine in 11% to 20% of patients.9 There is insufficient evidence to form conclusions regarding other antipsychotics. Fonseka et al9 recommends switching to an antipsychotic with lower 5HT-2 binding affinity or adding an SSRI, such as fluvoxamine, if induction or exacerbation of OCD symptoms occurs.
Consider long-term risks
The evidence for benefits with antipsychotics in treatment-resistant OCD is limited by different populations recruited, small sample sizes, and lack of long-term follow-up. Most evidence supports using ERP over antipsychotics for treating OCD symptoms that have not responded to SSRIs. However, ERP poses its own challenges that may limit clinical utility, such as economic and time restraints. Therefore, benefits with antipsychotics, such as risperidone and aripiprazole, must be weighed against potential long-term risks of treatment, including sedation, weight gain, metabolic syndrome, and extrapyramidal side effects.
Regarding Mr. E’s case, because he had been maximized on SSRI therapy for an adequate duration (escitalopram, 40 mg/d, for 12 weeks) and completed CBT with ERP with a partial response, adding risperidone, 0.5 mg at bedtime, was an appropriate treatment option that is supported by the available guidelines and evidence. The risperidone dose is reflective of the initial dosing strategies used in clinical trials. It is recommended to assess efficacy of treatment at 8 weeks with a validated measure, such as the Y-BOCS. A dose increase may be needed to achieve clinically significant symptom improvement, because moderate doses of risperidone have demonstrated efficacy in trials; however, high doses of risperidone are unlikely to provide additional benefit and increase the risk of adverse effects. If risperidone does not provide a clinically favorable risk–benefit ratio for Mr. E, aripiprazole is a potential alternative.