Meta-Regression Analysis to Indirectly Compare Prophylaxis With Dalteparin or Enoxaparin in Patients at High Risk for Venous Thromboembolic Events

Abstract

Background: Dalteparin and enoxaparin are recommended as thromboprophylaxis for at least 10 days in patients undergoing abdominal surgery (AS) or hospitalized patients with acute medical illnesses. Even though both agents have proven clinical effectiveness through randomized trials, there have been no head-to-head studies. In this evaluation, indirect statistical techniques were used to compare safety and efficacy between dalteparin and enoxaparin in these 2 high-risk patient populations. Methods: A literature search was conducted from January 1980 to November 2010 for randomized trials evaluating dalteparin or enoxaparin prophylaxis following AS or in hospitalized patients. Binary outcomes for safety and efficacy were statistically pooled using fixed or random effects models in cases of significant heterogeneity. In trials where a common control was used (eg, unfractionated heparin [UH]), indirect statistical comparisons between dalteparin and enoxaparin were performed using meta-regression analysis with active drug as the primary independent variable. Results: The meta-analysis in AS patients showed that enoxaparin or dalteparin had comparable efficacy to UH in terms of venous thromboembolic events (VTEs; relative risk reduction [RR] = 0.87, P = .46). The indirect statistical comparison was unable to find significant differences between enoxaparin and dalteparin in terms of risk for VTE ( P = .84), major bleeding ( P = .38), heparin-induced thrombocytopenia ([HIT]; P = .084), or death ( P = .97). In acutely ill medical patients, treatment with enoxaparin or dalteparin had a 52% VTE risk reduction compared to placebo (RR = 0.48, P < .001). The indirect comparison was also unable to find significant differences between enoxaparin and dalteparin in terms of VTEs ( P = .15), major bleeds ( P = .39), HIT ( P = .48), and death ( P = .41). Conclusions: The findings suggest comparable safety and efficacy between dalteparin and enoxaparin in AS and in acutely ill medical patients.