Background Atrial fibrillation (AF) is a stronger risk factor for cardiovascular disease in women than men. We assessed whether there are sex differences in the effects of 43 established and novel risk factors and the risk of incident AF.

Methods Data were used from the Scottish Heart Health Extended Cohort, a prospective cohort study with over 20 years of follow-up for AF incidence. Cox regression models were used to obtain the adjusted sex-specific HRs and 95% CIs, and the women-to-men ratio of HRs (RHRs), of incident AF associated with personal characteristics, smoking, physical measurements, diabetes mellitus, lipid, inflammatory, cardiac, and diet- and renal-related markers.

Results Overall, 15 737 participants (52% women) were included. There were sex differences in the relationship between a 1 SD increase in body mass index (BMI), NT-pro-BNP, uric acid, and cystatin-C and the risk of AF. The HRs were 1.17 (95% CI 1.08 to 1.27) in women and 1.36 (95% CI 1.24 to 1.49) in men for BMI (RHR 0.86, 95% CI 0.77 to 0.97); 1.84 (95% CI 1.62 to 2.09) in women and 1.54 (95% CI 1.40 to 1.68) in men for NT-pro-BNP (RHR 1.22, 95% CI1.05 to 1.42); 1.27 (95% CI 1.14 to 1.41) in women and 1.10 (95% CI 1.00 to 1.20) in men for uric acid (RHR 1.17, 95% CI 1.01 to 1.35); and 1.22 (95% CI 1.13 to 1.32) in women and 1.07 (95% CI 0.96 to 1.18) in men for cystatin-C (RHR 1.16, 95% CI 1.05 to1.27).

Conclusion Higher BMI is a stronger risk factor for AF in men whereas elevated NT-pro-BNP, uric acid and cystatin-C were more strongly associated with the risk of AF in women.