Individual patient data meta-analysis of enoxaparin vs. unfractionated heparin for venous thromboembolism prevention in medical patients.

Background: Unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) are both recommended for venous thromboembolism (VTE) prophylaxis in hospitalized medical patients.

Objective: To perform an individual patient data meta-analysis to evaluate the relative efficacy and safety of the LMWH enoxaparin and UFH in preventing VTE in hospitalized medical patients.

Methods: Randomized clinical trials comparing subcutaneous enoxaparin (4000 IU once-daily) and UFH (5000 IU subcutaneous two- or three-times daily) for VTE prevention were identified by a systematic search. Individual patient data were obtained from each eligible trial.

Results: Overall, four trials were eligible, including 3600 patients randomized to receive enoxaparin (n = 1799) or UFH (n = 1801). Median patient age was 71 years, and 49.3% were female. Compared with UFH, enoxaparin was associated with risk reductions of 37% for total VTE [relative risk (RR) 0.63, 95% confidence interval (CI) 0.51-0.77] and 62% for symptomatic VTE (RR 0.38, 95% CI 0.17-0.85) at day 15. RR for total VTE in stroke and non-stroke patients was 0.59 (95% CI 0.47-0.74) and 0.87 (95% CI 0.51-1.50), respectively. Major bleeding rates were consistently low and similar between treatment groups at day 15 (RR 1.13, 95% CI 0.53-2.44). There was a trend towards reduced risk for mortality in patients receiving enoxaparin (RR 0.83, 95% CI 0.64-1.08), compared with UFH.

Conclusions: Enoxaparin significantly reduces VTE in hospitalized medical patients, compared with UFH, without increasing the risk for major bleeding, and was associated with a trend towards reduced all-cause mortality.