Long-term Impact of Bariatric Surgery on Venous Thromboembolic Risk: A Matched Cohort Study.

OBJECTIVE: The aim of this study is to evaluate the effect of bariatric surgery on long-term risk of VTEs in a large cohort of patients with obesity.

BACKGROUND: Obesity is a well-established risk factor for VTEs, such as pulmonary embolism and deep vein thrombosis. The rising prevalence of obesity and its associated co-morbidities, including VTE, represent a growing public health issue.

METHODS: A nested, retrospective matched cohort study was designed and conducted on prospectively collected national electronic healthcare records data from the Clinical Practice Research Datalink. Eight thousand, one hundred twelve patients were included in the study: the 4056 patients on the database who had undergone bariatric surgery, and equal numbers of age, sex, and body mass index matched controls. The primary endpoint was the occurrence of VTEs; secondary endpoints were the occurrence of deep vein thrombosis alone, pulmonary embolism alone.

RESULTS: Patients were followed up for a median of 10.7 years. The bariatric surgery cohort had a significantly lower occurrence of the primary outcome [hazard ratio (HR) 0.601; 95% confidence interval (CI) 0.430-0.841, P = 0.003]; mainly driven by a reduction in deep vein thrombosis (HR 0.523; 95% CI 0.349-0.783, P = 0·002) and not in pulmonary embolism (HR 0.882; 95% CI 0.511-1.521, P = 0.651).

CONCLUSIONS: The results of this nation-wide study set out to characterize the impact of bariatric surgery on long-term risk of thromboembolic events outline a significant reduction in thromboembolic events, driven by a reduction in deep vein thrombosis.