Epidemiology of post-operative venous thromboembolism in Asian patients. Results of the SMART venography study.

BACKGROUND AND OBJECTIVES The rate of post-operative asymptomatic deep-vein thrombosis in Asian patients remains uncertain. The aim of this study was to estimate the rate of venous thromboembolism, including asymptomatic deep-vein thrombosis, undergoing hip or knee surgery and not receiving pharmacological thromboprophylaxis. DESIGN AND METHODS This was a prospective observational study of a cohort of consecutive Asian patients. The primary study outcome was the composite of venographically detected asymptomatic, or confirmed symptomatic venous thromboembolism, or sudden death at hospital discharge. Bilateral venography was to be performed in all patients between days 5 and 14 after surgery. Follow-up lasted 1 month. RESULTS A total of 386 patients (median age: 65 years, female: 63.7%, body-mass index > or = 30 kg/m2: 15.4%) undergoing hip (n=160) or knee (n=226) replacement surgery satisfied the study selection criteria and 326 (84.5%) had evaluable venograms. The rate of the primary outcome was 36.5% (119 patients, 99% confidence interval: 29.7 to 43.7). The rate of symptomatic venous thromboembolism was 0.9% (3 patients, 99% confidence interval: 0.1 to 3.3). During follow-up (358 patients for a median duration of 33 days after surgery), two additional episodes of symptomatic venous thromboembolism occurred. Multivariate analysis identified that knee replacement surgery, duration of surgery and treatment with antibiotics within 1 week before surgery were independent risk factors (p<0.05) for venous thromboembolism or sudden death at hospital discharge. INTERPRETATION AND CONCLUSIONS In Asian patients, the incidence of asymptomatic and symptomatic venous thromboembolism after major orthopedic surgery is high. These results suggest that thromboprophylaxis should be considered in these patients.