Rivaroxaban Deemed Safe, Effective for VTE Prophylaxis After Bariatric Surgery

Venous thromboembolism (VTE) is known to be a leading cause of morbidity and mortality following bariatric surgery. Research published in JAMA Network Open demonstrated that 10 mg of rivaroxaban a day for both 7 and 28 days following the surgery was both effective and safe for patients.

According to the study authors, this is the first study prospectively investigating an oral factor Xa inhibitor in patients after gastrointestinal surgery in general and in bariatric surgery specifically.

“All patients undergoing bariatric surgery are considered to be at least at moderate risk for VTE events because of severe obesity with associated comorbidities, laparoscopic surgery, and perioperative immobility,” the authors wrote. “Clinical guidelines recommend some form of pharmacologic thromboprophylaxis after bariatric surgery in addition to mechanical prophylaxis to reduce the risk of thromboembolic events. However, there is a lack of consensus regarding the optimal type, dose, and especially duration of pharmacologic prophylaxis after bariatric surgery.”

To assess this, between July 2018 and June 2021, the authors conducted an assessor-blinded, phase 2, multicenter randomized clinical trial in Switzerland involving 272 participants from 3 hospitals, both academic and non-academic.

The day following their bariatric surgery, participants were randomized to receive 10 mg of oral rivaroxaban for either 7 or 28 days, referred to as short and long prophylaxis, respectively. The primary measure of effectiveness focused on the combined occurrence of deep vein thrombosis—whether symptomatic or asymptomatic—and pulmonary embolism within 28 days after undergoing bariatric surgery. The main safety outcomes included significant bleeding events, clinically significant non-major bleeding, and mortality.

Among the 272 patients, the mean (SD) age was 40 (12.1) years, with a mean body mass index of 42.2. Most (80.3%) participants were women. Of this cohort, 134 patients were randomized to the short VTE prophylaxis course and 135 were randomized to the long VTE prophylaxis course.

During the study period, only 1 thromboembolic event occurred, accounting for 0.4% of total participants. According to the study authors, this event involved asymptomatic thrombosis in a patient who underwent sleeve gastrectomy and received extended prophylaxis. There were 5 patients (1.9%) who experienced major or clinically relevant non-major bleeding events, with 2 in the short prophylaxis group and 3 in the long prophylaxis group. Additionally, 10 patients (3.7%) experienced clinically insignificant bleeding events, with 3 in the short prophylaxis group and 7 in the long prophylaxis group.

While the amount of safety events was higher in the long prophylaxis group compared with the short prophylaxis group, this difference was not deemed statistically significant.

The subgroup analysis did not find any variation in VTE outcomes among patients who underwent different types of surgeries, such as sleeve gastrectomy, Roux-en-Y gastric bypass, or revisional surgery. According to the authors, there was also no difference observed within the subgroups based on the duration of prophylaxis. Because of this, they believe the type of surgical procedure does not appear to affect the effectiveness of thromboembolic prophylaxis. They also noted that none of the patients displayed clinically obvious signs or symptoms indicative of pulmonary embolism.

Low-molecular-weight heparins (LMWHs) are the most frequently prescribed pharmacologic prophylaxis for VTE after bariatric surgery. The study’s limitations include the lack of a LMWH treatment arm, preventing a direct comparison of thromboembolic prophylaxis effectiveness between rivaroxaban and LMWH. Also, the low number of primary outcome events was deemed noteworthy and unexpected by the study authors, making it difficult to directly compare efficacy between the 2 treatment length groups.

“Of note, this study was not designed to prove equivalence between the 2 treatment durations, and no equivalence testing has been planned or performed,” the authors said. “Testing for equivalence would have required a larger study population.”

The sample size of this trial is also relatively small compared to larger phase 3 trials. However, it is the first randomized clinical study to investigate thromboembolic prophylaxis using a direct oral anticoagulant (DOAC) in bariatric surgery, and the inclusion of compression ultrasound to detect asymptomatic deep vein thrombosis enhances the validity of the efficacy findings, according to the authors.

“A larger prospective trial in patients undergoing bariatric surgery comparing thromboembolic prophylaxis with short-term DOAC and extended LMWH treatment would be valuable to confirm the results of this study and to guide future prophylactic treatment,” the authors closed.

Reference

Kröll D, Nett PC, Rommers N, et al. Efficacy and safety of rivaroxaban for postoperative thromboprophylaxis in patients after bariatric surgery: a randomized clinical trial. JAMA Netw Open. Published online May 1, 2023. doi:10.1001/jamanetworkopen.2023.15241