Impact of obesity on real-world clinical outcomes in patients with atrial fibrillation on direct oral anticoagulant therapy : a retrospective cohort study

Objectives: To assess the impact of body mass index on real-world clinical outcomes in patients with atrial fibrillation taking direct oral anticoagulants (DOACs) within the Baylor Scott & White healthcare system.
Methods: This was a retrospective, observational cohort study of adult patients (≥18 years of age) with atrial fibrillation or atrial flutter with ≥1 pharmacy claim for a DOAC (dabigatran, rivaroxaban, apixaban, edoxaban) between 2015 and 2017. Patients were stratified into cohorts based on body mass index: normal weight, overweight, obese class I, obese class II, obese class III. The primary effectiveness outcome was any stroke or systemic embolic event and the primary safety outcome was any major bleed event. Baseline characteristics across the cohorts were compared descriptively and using bivariate analyses. Unadjusted outcome event rates across the cohorts were compared descriptively. Results: The primary analysis consisted of 1,035 patients (normal 245 (23.4%), overweight 352 (33.6%), obese class I 220 (21.0%), obese class II 132 (12.6%), and obese class III 86 (8.2%)). Overweight and obese cohorts were younger and had a lower proportion of females, Medicare insurance, prior stroke/transient ischemic attack (TIA) and bleed history, higher proportions of hypertension and diabetes rates, and lower CHA₂DS₂-VASc and HAS-BLED scores than the normal weight cohort.. Eleven (1.1%) stroke or systemic embolic events were observed and similar rates were seen across the BMI cohorts (normal 3 (1.2%), overweight 3 (0.9%), obese class I 3 (1.4%), obese class II 1 (0.8%), obese class III 1 (1.2%)). About three percent (n= 29; 2.8%) of those studied had major bleed events and decreasing rates were seen with increasing BMI cohorts (normal 9 (3.7%), overweight 11 (3.1%), obese class I 5 (2.3%), obese class II 3 (2.3%), obese class III 1 (1.2%)). Conclusion: A small percentage of stroke/systolic embolism and major bleed event rates were observed across all BMI groups, such that no statistical tests could be performed to compare the event rates among the BMI groups. DOAC-receiving atrial fibrillation patients who are overweight or obese may see similar, and potentially lower, rates of stroke and systemtic emoblism or major bleed events compared to normal weight patients.