Association of Body Mass Index With Care and Outcomes in Patients With Atrial Fibrillation: Results From the ORBIT-AF Registry

Objectives This study sought to determine the association between body mass index (BMI) and clinical outcomes among patients with prevalent atrial fibrillation (AF). Background Higher BMI is an independent risk factor for incident AF. However, its impact on management strategies and clinical outcomes among patients with prevalent AF is unclear. Methods Patients with AF enrolled in the ORBIT-AF (Outcomes Registry for Better Informed Treatment of Atrial Fibrillation) registry from June 2010 through August 2011 were stratified into BMI-based categories as normal weight, overweight, class I obese, class II obese, and class III obese. Unadjusted and adjusted Cox frailty models were constructed to assess the association of BMI with clinical outcomes over a 2-year follow-up. Results We evaluated 9,606 patients with AF (42% women; 78% overweight/obese) from 174 ORBIT participating practices in the United States. Higher BMI patients were younger and had a greater prevalence of diabetes, hypertension, and obstructive sleep apnea (OSA). Use of anticoagulation and rhythm control strategies was significantly greater among higher BMI patients. Rates for all-cause mortality and thromboembolic events decreased in a near linear fashion across increasing BMI categories (p < 0.001). After multivariable adjustment, higher BMI was associated with lower risk for all-cause mortality with lowest risk among class I obese patients (hazard ratio [HR]: 0.65; 95% CI: 0.54 to 0.78); reference: normal weight). For every 5-kg/m² increase in BMI, the odds of risk-adjusted mortality were 7% lower. In contrast, BMI was not associated with adjusted risk for thromboembolic events and AF progression. Conclusions Although AF patients with higher BMI were significantly younger, higher BMI in AF patients was associated with similar or better clinical outcomes.