Association between body mass index and the risk of bleeding in elderly patients with non-valvular atrial fibrillation taking dabigatran: a cohort study

BACKGROUND: Uncertainty remains regarding the association between body mass index (BMI) and the risk of bleeding in patients with non-valvular atrial fibrillation (NVAF). We aimed to investigate the association between BMI and the risk of bleeding in elderly NVAF patients taking dabigatran. METHODS: A total of 509 elderly NVAF patients, who were being treated at twelve centers in China from February 2015 to December 2017 and taking dabigatran, were analyzed. The exposure and outcome variables were BMI at baseline and bleeding events within the subsequent six months, respectively. Cox proportional hazards regression analysis was used to evaluate the association between BMI and the risk of bleeding. Moreover, the Cox proportional hazards regression with cubic spline functions and smooth curve fitting was conducted. RESULTS: During the six-month follow-up, 50 participants experienced bleeding. Every 1 kg/m(2) increase in BMI was associated with a 12% increased risk of bleeding (P = 0.021). Compared to those with BMI values in Tertile 1 (< 22.5 kg/m(2)), the adjusted hazard ratio (HR) of bleeding for participants in Tertile 2 (22.5–25.3 kg/m(2)) and Tertile 3 (> 25.3 kg/m(2)) were 2.71 (95% CI: 1.02–7.17) and 3.5 (95% CI: 1.21–8.70), respectively. The P(trend)-value was significant in all models. The adjusted smooth curve showed a linear association between BMI and bleeding. None of the stratified variables showed significant effect modification on the association between BMI and bleeding (P(interaction) > 0.05). CONCLUSIONS: BMI was significantly and positively associated with the risk of bleeding in elderly NVAF patients treated with dabigatran.