The prevalence and predictors of comorbid bipolar disorder and obsessive-compulsive disorder: A systematic review and meta-analysis

•BD-OCD comorbidity is a critical issue in psychiatry.•The pooled prevalence of both OCD in BD and BD in OCD was around 17.0-18.0%.•Further studies are needed to clarify BD-OCD clinical meaning and treatment approach.

Background: Although some authors have recently investigated the co-occurrence of anxiety and bipolar disorders, the topic remains insufficiently studied. Defining the prevalence and predictors of BD-OCD comorbidity has important nosological, clinical and therapeutic implications.Methods: A systematic review and meta-analysis was conducted on the prevalence and predictors of comorbid BD-OCD. Relevant papers published through March 30th, 2015 were identified searching the electronic databases MEDLINE, Embase, PsycINFO and the Cochrane Library.Results: 46 articles met inclusion criteria. The pooled prevalence of OCD in BD was 17.0% (95% CI 12.7-22.4%), which was comparable to the results reported by the pooled prevalence of BD in OCD (18.35%, 95% CI 13.2-24.8%). With regard to OCD-BD predictors, a higher mean age predicted a lower prevalence of OCD in BD patients. Sub group meta-analyses reported higher OCD prevalence rates in BD children and adolescents (24.2%, compared to 13.5% in adults), in BD-I patients (24.6%, compared to 13.6% in mixed BD patients), and among population-based studies (22.2%, compared to 13.2% in hospital-based studies).Limitations: Most studies use retrospective assessment scales with low sensitivity in discriminating true ego-dystonic obsessions from depressive ruminations that may bias results towards an overestimation of obsessive symptom prevalence.Conclusions: This first systematic review and meta-analysis of the prevalence and predictors of comorbid BD-OCD confirms that BD-OCD comorbidity is a common condition in psychiatry with children and adolescents and BD-I patients as the most affected subgroups.