Association between REM sleep behavior disorder and impulsive–compulsive behaviors in Parkinson’s disease: a systematic review and meta-analysis of observational studies

Background Both REM sleep behavior disorder (RBD) and impulsive–compulsive behaviors (ICBs) are well-recognized non-motor features in patients with Parkinson’s disease (PD). Studies have given contradictory results about the potential association between RBD and ICBs. Methods PubMed, Embase (via Ovid), and the Cochrane Central Registry of Controlled Trials (CENTRAL) databases were systematically searched till August 20, 2019 to identify studies that explored the possible correlation between RBD and ICBs in patients with PD. Two authors independently screened records, extracted data and evaluated quality of included studies. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated by employing a random or fixed-effects model. We performed subgroup and sensitivity analyses, and we assessed potential publication bias. Results A total of 134 references were screened and 10 studies involving 2781 PD patients were included. Overall, RBD was associated with a more than twofold higher risk of developing ICBs (OR 2.12, 95% CI 1.43–3.14, I 2 = 56.7%, P