A Systematic Review of Evidence-based Treatment Strategies for Obsessive- compulsive Disorder Resistant to first-line Pharmacotherapy

Background: Serotonin reuptake inhibitors (SRIs) and cognitive-behavioral psychotherapy (CBT) are first-line treatments for obsessive-compulsive disorder (OCD). However, a significant proportion of patients do not respond satisfactorily to first-choice treatments. Several options have been investigated for the management of resistant patients.

Objective: The aim of the present paper is to systematically review the available literature concerning the strategies for the treatment of resistant adult patients with OCD.

Method: We first reviewed studies concerning the definition of treatment-resistant OCD; we then analyzed results of studies evaluating several different strategies in resistant patients. We limited our review to double-blind, placebo-controlled studies performed in adult patients with OCD whose resistance to a first adequate (in terms of duration and dosage) SRI trial was documented and where outcome was clearly defined in terms of decrease in Yale-Brown Obsessive-Compulsive Scale (YBOCS) scores and/or response/ remission rates (according to the YBOCS).

Results: We identified five strategies supported by positive results in placebo-controlled randomized studies: 1) antipsychotic addition to SRIs (16 RCTs, of them 10 positive; 4 head-to-head RCTs); among antipsychotics, available RCTs examined the addition of haloperidol (butyrophenone), pimozide (diphenyl-butylpiperidine), risperidone (SDA: serotonin- dopamine antagonist), paliperidone (SDA), olanzapine (MARTA: multi-acting receptor targeted antipsychotic), quetiapine (MARTA) and aripiprazole (partial dopamine agonist); 2) CBT addition to medication (2 positive RCTs); 3) switch to intravenous clomipramine (SRI) administration (2 positive RCTs); 4) switch to paroxetine (SSRI: selective serotonin reuptake inhibitor) or venlafaxine (SNRI: serotonin-norepinephrine reuptake inhibitor) when the first trial was negative (1 positive RCT); and 5) the addition of medications other than an antipsychotic to SRIs (18 RCTs performed with several different compounds, with only 4 positive studies).

Conclusion: Treatment-resistant OCD remains a significant challenge to psychiatrists. To date, the most effective strategy is the addition of antipsychotics (aripiprazole and risperidone) to SRIs; another effective strategy is CBT addition to medications. Other strategies, such as the switch to another first-line treatment or the switch to intravenous administration are promising but need further confirmation in double-blind studies. The addition of medications other than antipsychotics remains to be studied, as several negative studies exist and positive ones need confirmation (only 1 positive study).