In-Hospital VTE Risk Despite Recommended Prophylaxis after Hip, Knee Arthroplasty

A systematic review of the available literature has revealed that patients undergoing total or partial hip or knee arthroplasty may be at risk for venous thromboembolism (VTE) events, including deep vein thrombosis (DVT) or pulmonary embolism (PE), despite recommended prophylaxis. The findings were reported in the Journal of the American Medical Association [2012;307(3):294-303]. The study authors included researchers from Switzerland, France, and Canada. Their systematic literature review and meta-analysis included randomized clinical trials testing the efficacy of VTE prophylaxis regimens and observational studies of patients receiving VTE prophylaxis. Studies were included if they reported confirmed postoperative symptomatic VTE that occurred prior to hospital discharge following total or partial knee arthroplasty (TPKA) or total or partial hip arthroplasty (TPHA). A total of 47 studies were included in the analysis, of which 6 were observational studies and 41 were randomized controlled trials. The trials included 21 describing patients undergoing hip arthroplasty, 20 describing patients undergoing knee arthroplasty, and 6 that included both knee and hip arthroplasty patients. The VTE prophylaxis regimens evaluated in the studies included low-molecular-weight heparin (LMWH), oral direct factor Xa/IIa inhibitors, or indirect factor Xa/IIa inhibitors. All of the observational studies were in patients receiving LMWH prophylaxis. The analysis found that in patients undergoing TPHA, the pooled incidence rates were 0.53% for symptomatic postoperative VTE, 0.26% for DVT, and 0.14% for PE. In patients undergoing TPKA, pooled incidence rates were 1.09%, 0.63%, and 0.27% for symptomatic postoperative VTE, DVT, and PE, respectively. The risk of VTE varied by type of prophylaxis therapy. For instance, VTE rates were 1.42% and 0.58% in TPKA and TPHA studies, respectively. Prophylaxis with an oral direct factor Xa/IIa inhibitor in TPKA and TPHA was associated with VTE rates of 0.81% and 0.31%. There was no appreciable difference between VTE incidence rates in randomized controlled trials and observational studies with LMWH prophylaxis. Overall, the authors reported pooled in-hospital incidence rates of symptomatic postoperative VTE of approximately 1% following TPKA and approximately 0.5% after TPHA among patients who received recommended VTE prophylaxis during hospitalization. Based on these findings, the authors noted that approximately 1 in 100 patients undergoing TPKA, and 1 in 200 patients undergoing TPHA, would experience a VTE event before discharge, despite recommended VTE prophylaxis. The authors noted that the findings could be used to propose a benchmark value for the incidence of postoperative VTE. As postoperative VTE has been identified as a patient safety indicator by organizations such as the Agency for Healthcare Research and Quality, a benchmark value might be used to validate this safety indicator, the authors explained. Study limitations discussed by the authors included the fact that some relevant studies, especially observational studies, could have been missed in their search. In addition, most of the studies included in the analysis were randomized controlled trials, which could have affected the patient population represented. Finally, the year or the country in which the study was conducted could have impacted thromboprophylaxis strategies. The authors also cautioned that comparative efficacy between specific thromboprophylaxis strategies could not be inferred outside of the setting of randomized trials in a common pool of patients.