Association between serum uric acid and atrial fibrillation: A systematic review and meta-analysis

BACKGROUND Atrial fibrillation (AF) is mediated by oxidative stress, neurohormonal activation, and inflammatory activation. Serum uric acid (SUA) is a surrogate marker of oxidative stress. Xanthine oxidase produces SUA and is upregulated by inflammation and neurohormones. OBJECTIVE To perform a meta-analysis to evaluate the evidence supporting an association between AF and SUA. METHODS We searched the MEDLINE database (1966 to 2013) supplemented by manual searches of bibliographies of key relevant articles. We selected all cross-sectional and cohort studies in which SUA was measured and AF was reported. In cross-sectional studies, we calculated the pooled standardized mean difference of SUA between those with AF and those without AF. In cohort studies, we calculated the pooled relative risk with the corresponding 95% confidence interval (CI) for incident AF by using the random effects method. RESULTS The search strategy yielded 40 studies, of which only 9 met our eligibility criteria. The 6 cross-sectional studies comprised 7930 evaluable patients with a median prevalence of heart failure of 4% (IQR 0%-100%). The standardized mean difference of SUA for those with AF was 0.42 (95% CI 0.27-0.58) compared with those without AF. The 3 cohort studies evaluated 138,306 individuals without AF. The relative risk of having AF for those with high SUA was 1.67 (95% CI 1.23-2.27) compared with those with normal SUA. CONCLUSION High SUA is associated with AF in both cross-sectional and cohort studies. It is unclear whether SUA represents a disease marker or a treatment target.