The relationship between vitamin D and risk of atrial fibrillation: a dose-response analysis of observational studies

Background The relationship between serum vitamin D and atrial fibrillation (AF) or postoperative atrial fibrillation (POAF) in patients undergoing coronary artery bypass graft (CABG) is still debated. It is also unclear whether there is a dose-response relationship between circulating vitamin D and the risk of AF or POAF. Methods The Cochrane Library, PubMed, and Embase databases were searched for relevant studies. We used a “one-stage approach” with a restricted cubic spline model to summarize the dose-specific relationships between serum vitamin D and AF. Relative risk (RR) was used to measure the effects in this meta-analysis. Results In total, 13 studies were included with a total of 6519 cases of AF among 74,885 participants. Vitamin D deficiency (< 20 ng/ml) was associated with increased risks of AF (RR: 1.23, 95% CI: 1.05–1.43). In the dose-response analysis, the summary RR for a 10 ng/ml increased in vitamin D was 0.88 (95% CI: 0.78–0.98) and there was no evidence of a non-linear association, P non-linearity = 0.86. In the age subgroup, high vitamin D (per 10 ng/ml increase) reduced the risk of AF in the older group (> 65 years) (RR = 0.68, 95% CI = 0.52–0.89) but not among young individuals (< 65 years) (RR = 0.87, 95% CI = 0.72–1.06). In addition, a strong association was found between a 10 ng/ml increased in vitamin D and POAF incident in the patient after CABG (RR: 0.44, 95% CI: 0.24–0.82). Conclusion Our dose-response meta-analysis suggested serum vitamin D deficiency was associated with an increased risk of AF in the general population and POAF in patients after CABG. Further studies are needed to explore the age difference in the association between serum vitamin D level and the risk of AF and whether vitamin D supplements will prevent AF. Trial registration This study has been registered with PROSPERO (International prospective register of systematic reviews)-registration number- CRD42019119258 .