Red blood cell distribution width as a predictor of atrial fibrillation

Background: Current evidence suggests that a higher red blood cell distribution width (RDW) may be associated with increased risk of atrial fibrillation (AF) development. Given that some controversial results have been published, we conducted a systematic review of the current literature along with a comprehensive meta-analysis to evaluate the association between RDW and AF development. Methods: We performed a systematic search of the literature using electronic databases (PubMed, Ovid, Embase, and Web of Science) to identify studies reporting on the association between RDW and AF development published until June 2016. We used both fix-effects and random-effects models to calculate the overall effect estimate. An I² > 50% indicates at least moderate statistical heterogeneity. A sensitivity analysis and subgroup analysis were performed to find the origin of heterogeneity. Results: A total of 12 studies involving 2721 participants were included in this meta-analysis. The standardized mean difference in the RDW levels between patients with and those without AF development was 0.66 units (P <.05; 95% confidence interval 0.44-0.88). A significant heterogeneity between the individual studies was observed (P <.05; I² = 80.4%). A significant association between the baseline RDW levels and AF occurrence or recurrence following cardiac procedure or surgery was evident (SMD: 0.61; 95% confidence interval 0.33-0.88; P <.05) with significant heterogeneity across the studies (I² = 80.7%; P <.01). Conclusions: Our comprehensive meta-analysis suggests that higher levels of RDW are associated with an increased risk of AF in different populations.