The effect of aspirin and low-molecular-weight heparin on venous thromboembolism after knee replacement: a non-randomised comparison using National Joint Registry data

BackgroundThe most appropriate form of chemical thromboprophylaxis following knee replacement is a contentious issue. Most national guidelines recommend the use of low molecular weight Heparin (LMWH) whilst opposing the use of aspirin. We compared thromboembolic events, major haemorrhage and death after knee replacement in patients receiving either aspirin or LMWH.MethodsData from the National Joint Registry for England and Wales was linked to an administrative database of hospital admissions in the English National Health Service. A total of 156 798 patients undergoing knee replacement between April 2003 and September 2008 were included and followed up for 90 days. Multivariable risk modelling was used to estimate odds ratios adjusted for baseline risk factors (AOR). An AOR < 1 indicates that risk rates are lower with LMWH than with aspirin.ResultsIn all, 23.1% of patients were prescribed aspirin and 76.9% LMWH. We found no statistically significant differences in the rate of pulmonary embolism (aspirin ...