Venous thromboembolism after major orthopaedic surgery: a population-based cohort study.

Venous thromboembolism (VTE) is an important cause of morbidity and mortality following major orthopaedic surgery. However, the incidence of VTE and the role of additional risk factors have not yet been well explored in Italian clinical practice. The objective of the study is to estimate the incidence of VTE in the 3 months following elective hip and knee replacement (HR, KR) in a large cohort of patients, and the association between some selected risk factors and the occurrence of VTE. A large cohort study based on the record linkage between automated archives of the National Health System was analysed. In particular, all the residents in the Lombardy Region (Italy) who underwent HR and KR between 2005 and 2008 were followed for 3 months after surgery. The odds ratio (OR) of VTE associated with selected known risk factors was estimated by multivariate logistic regression. Amongst the 69,770 patients included in the study, 2,393 experienced at least one VTE event during the follow-up; the overall risk of VTE after HR or KR was 3.4%. The adjusted odds of experiencing a VTE event was higher in male patients (OR 1.11; 95% confidence interval 1.01-1.21), aged 60 years or older (1.30; 1.00-1.68), undergoing KR (1.47; 1.35-1.61), with previous deep vein thrombosis (1.96; 1.20-3.19), pulmonary embolism (3.25; 1.84-5.75) or cancer (1.21; 1.00-1.46). In conclusion, the incidence of VTE after elective HR and KR in the Italian clinical practice is high. Our results suggest the need of optimising the management of thromboprophylaxis to further reduce postoperative VTE.