Background: There is limited information on the influence of body mass index (BMI) on clinical outcomes in patients with venous thromboembolism (VTE).

Objectives: Investigate the influence of BMI on baseline characteristics, treatment patterns, and 24-month outcomes in VTE patients.

Methods: GARFIELD-VTE is a prospective, non-interventional study of 10 869 patients with objectively confirmed VTE. Patients were grouped according to BMI: <18.5 (underweight; n = 214); 18.5-24.9 (normal; n = 2866); 25.0-29.9 (overweight; n = 3326); ≥30 (obese; n = 3073).

Results: Compared with patients with a normal BMI, obese patients were more frequently Caucasian (77.4% vs. 57.9%), treated in the outpatient setting (30.4% vs. 23.1%), and had previous VTE (17.5% vs. 11.7%). Active cancer was associated with lower BMI (underweight: 30.4%, normal: 13.5%, overweight: 9.4%, obese: 7.0%). At baseline, overweight and obese patients less often received parenteral therapy alone (16.7% and 14.4%) compared with those with an underweight or normal BMI (30.8% and 21.6%). Obese patients more commonly remained on anticoagulants for ≥2-years compared to those with a normal BMI (52.3% vs. 37.7%). After 24-months, the risk of all-cause mortality was lower in overweight and obese patients than in those with normal BMI (adjusted hazard ratio [95% CI]; 0.75 [0.63-0.89] and 0.59 [0.49-0.72], respectively). Underweight patients more often experienced major bleeding (2.45 [1.41-4.26]) and all-cause mortality (1.90 [1.43-2.53]) than patients with a normal BMI. Recurrent VTE was comparable among groups.

Conclusion: Underweight VTE patients have the highest risk of mortality and major bleeding. The risk of mortality in obese VTE patients is lower than that in VTE patients with a normal BMI.