Impact of thromboprophylaxis timing and duration on thromboembolism and bleeding in metabolic bariatric surgery

BACKGROUND: Patients undergoing metabolic bariatric surgery are at risk of both venous thromboembolism (VTE) and bleeding complications, but the optimal thromboprophylaxis strategy remains uncertain. Therefore, this retrospective cohort study evaluated perioperative outcomes depending on the perioperative thromboprophylaxis strategy. METHODS: This study used data from the validated nationwide Scandinavian Obesity Surgery Registry, including all primary bariatric procedures in Sweden between 2008 and 2023. Exposures were timing of initiation (preoperative, postoperative, other) and the duration of thromboprophylaxis (< 7, 7-10, 11-14, or > 14 days). The primary outcome was VTE; secondary outcomes were intraoperative and postoperative bleeding. Outcomes were analysed using logistic regression models, adjusting for demographic, clinical, and surgical covariates. RESULTS: Among 83 801 patients (76.9% female, mean age 40.9 years, mean body mass index 41.8 kg/m2), the incidences of VTE, intraoperative bleeding, and postoperative bleeding were 0.1% (76 patients), 0.7% (577), and 1.6% (1373), respectively. No statistically significant associations were observed between the timing of thromboprophylaxis and VTE, or between thromboprophylaxis duration and either VTE or postoperative bleeding. Initiation of prophylaxis after surgery was associated with a lower risk of intraoperative bleeding than preoperative initiation (odds ratio 0.52; 95% confidence interval 0.37 to 0.74). Risk factors for VTE included previous VTE, intraoperative bleeding, and longer operating time, whereas risk factors for postoperative bleeding included higher age, male sex, cardiovascular co-morbidity, and antidepressant use. CONCLUSION: The overall incidence of thrombotic complications after metabolic bariatric surgery was low, whereas bleeding events were more common. Compared with preoperative thromboprophylaxis initiation, postoperative initiation was associated with reduced intraoperative bleeding, whereas no increase in VTE was detected.