Lower early mortality after acute pulmonary embolism in patients with WHO-defined obesity: results from a post-hoc cohort analysis with external validation

Abstract Background The relationship between obesity, defined as a Body Mass Index (BMI) ≥ 30 kg/m2, and mortality in venous thrombo-embolism remains controversial. Objectives To compare early outcomes after pulmonary embolism (PE) between obese patients, and non-obese, non-underweight patients. Methods We performed a post-hoc analysis based on prospectively recorded individual patient data from the multicenter BFC-FRANCE registry. We compared rates of outcomes using multivariable logistic regression or a Cox model for 30-day and 6-month outcomes respectively. We assessed the incremental value of adding BMI information on top of the 30-day European Society of Cardiology (ESC) prognostic algorithm. Results A total of 2,390 patients with a BMI ≥ 18.5 kg/m2 (mean age, 66.9±16.8 years; 1,188 men [49.7%]) were included, 686 patients [28.7%] in the obese group, and 1,704 patients [71.3%] in the non-obese group. Mortality rates were significantly lower in obese patients versus non-obese patients at 30 days (OR, 0.59; 95% CI, 0.35-0.98), and 6 months. Cox-model-derived adjusted curves for all-cause death at 6 months, with hazard ratios (HRs) between obese and non-obese patients, after acute PE, are shown in the Figure. Rates of secondary non-fatal outcomes (including recurrent VTE) did not differ between groups. The addition of the obesity information on top of the ESC prognostic model improved global model fit, and discriminatory and calibration capacities, yielding significant reclassification based on the observed mortality rates with the ESC model as reference. Findings were confirmed in an external validation using 35,796 PE patients from the RIETE registry. Conclusion We present evidence indicating lower early and mid-term mortality after PE in patients classified as obese based on BMI, compared with non-obese, non-underweight patients. BMI should likely be incorporated into algorithms or scoring systems for predicting early mortality following PE.