Is Infection an Independent Risk Factor for Venous Thromboembolism? A Population-Based, Case-Control Study

Background: The independent association of recent infection with venous thromboembolism is uncertain. The study aims were to test both overall infection (site unspecified) and specific infection sites as potential risk factors for deep vein thrombosis and pulmonary embolism adjusting for other known venous thromboembolism factors. Methods: By using Rochester Epidemiology Project resources, we identified all Olmsted County, Minnesota, residents with objectively diagnosed incident deep vein thrombosis or pulmonary embolism over the 13-year period 1988 to 2000 (cases; n = 1303) and 1 to 2 residents without venous thromboembolism matched to each case on age, sex, and incident venous thromboembolism date (controls; n = 1494). Using conditional logistic regression, we tested recent infection and infection site(s) for an association with venous thromboembolism, adjusting for body mass index, smoking, current/recent hospitalization with/without surgery, nursing home confinement, active cancer, trauma/fracture, leg paresis, prior superficial vein thrombosis, transvenous catheter/pacemaker, ischemic heart disease, congestive heart failure, chronic lung or renal disease, serious liver disease, asthma, diabetes mellitus, hormone therapy, and pregnancy/postpartum. Results: A total of 513 cases (39.4%) and 189 controls (12.7%) had an infection in the previous 92 days (odds ratio, 4.5; 95% confidence interval, 3.6-5.5; P <.0001). In a multivariable analysis adjusting for common venous thromboembolism risk factors, pneumonia and symptomatic urinary tract, oral, intra-abdominal, and systemic bloodstream infections were associated with significantly increased odds of venous thromboembolism. Conclusions: Infection as a whole and specific infection sites in particular are independent risk factors for venous thromboembolism and should be considered as potential indications for venous thromboembolism prophylaxis.