Influence of patient's weight and body mass index on presentation, time of onset, and impact of postoperative venous thromboembolism (RIETE registry).

The influence of weight and body mass index (BMI) on the initial presentation of venous thromboembolism (VTE) has not been consistently studied in patients undergoing non-bariatric surgery. This study aimed to assess and compare the time-course, initial presentation, and 3-month outcomes of patients with acute VTE after non-orthopedic surgery, according to weight and BMI. We conducted an observational study using an international database (RIETE registry), an ongoing inception cohort of patients with confirmed postoperative VTE. A total of 3196 patients were included during the study period (2001-2019). The median age was 62 years, 51.7% were female, and 2195 patients (68.7%) had overweight or obesity. Overall, 46.2% presented with isolated deep vein thrombosis (DVT). The percentage of patients with pulmonary embolism (PE) significantly increased with BMI: 49.4% in normal weight, 54% in overweight and 58.5% in obesity. The median duration of VTE prophylaxis and the time from surgery to VTE detection was shorter in patients with higher weight. Bleeding rates decreased in those patients weighing > 100 kg (3.7%), compared to 7.9% and 15.2% in the 50-100 kg and < 50 kg groups, respectively. Mortality rate was significantly higher in normal weight patients (12.2%) compared to overweight (7.7%) and obese patients (5.8%). The proportion of patients with PE increased significantly with BMI and weight. Interval between surgery and detection of VTE was shorter in patients with obesity, with most thrombotic events occurring after discontinuation of pharmacological prophylaxis. The use and duration of thromboprophylaxis were lower than current guidelines recommend for patients with obesity.