Deep Vein Thrombosis Risk Declines After Bariatric Surgery

By Will Boggs MD

December 31, 2019

NEW YORK (Reuters Health) - Bariatric surgery is associated with a significant decrease in the long-term risk of venous thromboembolic events (VTEs), principally deep vein thrombosis (DVT), according to findings from the UK Clinical Practice Research Datalink (CPRD).

Obesity is associated with a 2- to 3-fold increased risk of VTEs, including pulmonary embolism and DVT. Surgery is also a risk factor for VTE, and the long-term effect of bariatric surgery on VTE remains unclear.

Dr. Maddalena Ardissino from Imperial College London and colleagues analyzed data from 8146 obese patients, including 4073 who had undergone bariatric surgery and 4073 matched controls.

During a median follow-up of 10.7 years, the adjusted rates of VTE were significantly lower in the bariatric surgery group (1.7%) than in the control group (4.4%), with a number needed to treat (NNT) to prevent 1 VTE of 37, according to the online report in Annals of Surgery.

This difference was driven by significant differences in DVT events (1.1% after bariatric surgery versus 3.4% among controls), whereas the rate of pulmonary embolism events did not differ significantly between the groups.

All-cause mortality was significantly lower in the bariatric surgery group (1.3%) than in the control group (4%).

The strongest reduction in VTE risk was observed in patients with class II obesity (BMI 35-40), with a smaller effect in patients with class I obesity (BMI 30-35), and no significant reduction in patients with class III obesity (BMI above 40).

"Overall, this study adds to the rapidly growing pool of evidence that highlights the wide-ranging metabolic, clinical, and lifestyle benefits of bariatric surgery for the management of patients with obesity and provides new knowledge regarding its effect on lowering long-term VTEs in this high-risk population," the researchers conclude.

Dr. Jon C. Gould from Medical College of Wisconsin, in Milwaukee, who has researched various aspects of bariatric surgery, told Reuters Health by email, "The body of literature outlining the long-term benefits of bariatric surgery from a health, quality of life, and cost perspective is robust. This is one more example of a positive impact of bariatric surgery over a very long term."

"In many parts of the United States, access to bariatric surgery is limited by arbitrary insurance exclusions," he said. "This is short-sighted. Far less than 1% of the eligible population undergoes a bariatric procedure in the U.S., mostly due to these access issues."

Dr. Shaun Daly from University of California Irvine Medical Center, in Orange, who recently reported risk factors for VTE after bariatric surgery, told Reuters Health by email, "While there is a known increased risk of short-term VTE in obese patients undergoing weight-loss surgery, the long-term reduction in VTE, specifically DVT, appears to outweigh this risk and improves overall health and risk in obese patients."

"Surgery reduces long-term VTE risk compared to matched obese individuals, (but) the long-term risk in both these populations remains higher than the general non-obese population, and a high level of suspicion needs to be maintained in any obese patient with potential signs and symptoms of VTE disease, post-surgery or not," he said.

Dr. Ardissino did not respond to a request for comments.

SOURCE: Annals of Surgery, online December 17, 2019.