Is Intensive Cognitive Behavioural Therapy an Efficacious and Acceptable Treatment Format for Adults with Obsessive Compulsive Disorder? A Systematic Review of Randomised Controlled Trials

Background: Clinical guidelines recommend the use of an intensive version of cognitive behavioural therapy (iCBT) in obsessive compulsive disorder (OCD) when evidence-based treatment has previously failed. This systematic review aimed to 1) assess the efficacy of iCBT for adults with OCD; 2) assess the acceptability of iCBT for adults with OCD.Methods: PROSPERO ID: CRD42018106840. We searched the Cochrane Controlled Register of Trials (CENTRAL), Cochrane Library, PubMed, Embase and PsycINFO for articles published between 1966 and November 2018, and reference lists and other sources for registered or ongoing studies. We included Randomised Controlled Trials (RCTs) of adults with OCD comparing iCBT to active or non-active controls. iCBT was defined as: at least five hours of CBT delivered per week in no more than four weeks for at least 10 CBT hours. The primary outcome was change in OCD symptoms from baseline to follow-up; secondary outcome was attrition; risk of bias was assessed using the Cochrane Tool. Results: Searches retrieved 5125 records, with only four RCTs with a total of 313 participants meeting inclusion criteria. Large effect sizes in favour of iCBT relative to controls were found, range (1.35 to 3.18). Drop-out rate across studies was low. However, none of the included studies focused on participants with a specific history of treatment failure. Studies were highly heterogeneous, which precluded meta-analysis. Conclusions: There was evidence that iCBT may be efficacious and acceptable. Further high quality RCTs are required to assess the efficacy and acceptability of iCBT specifically for OCD non-responders.