COST-EFFECTIVENESS OF ENOXAPARIN VERSUS WARFARIN PROPHYLAXIS AGAINST DEEP-VEIN THROMBOSIS AFTER TOTAL HIP-REPLACEMENT

Objective: To compare the efficacy and cost-effectiveness of enoxapari n, a low-molecular-weight heparin derivative, with that of low-dose wa rfarin in the prevention of deep-vein thrombosis (DVT) after total hip replacement. Data sources: English-language articles on enoxaparin an d warfarin prophylaxis in patients undergoing total hip replacement pu blished from January 1982 to December 1992. Study selection: Four tria ls of enoxaparin (involving 567 patients) and six trials of warfarin ( involving 630) met the following criteria: randomized controlled trial , prophylaxis started no later than 24 hours after surgery and continu ed for at least 7 days, warfarin dose monitored and adjusted appropria tely, enoxaparin dosage 30 mg twice daily, and DVT confirmed by bilate ral venography. Data extraction: Rates of DVT, cost of prophylaxis, di agnosis and treatment per patient, rate of pulmonary embolism (PE), nu mber of deaths and incremental cost-effectiveness (cost per life-year gained). Data synthesis: The pooled rate of DVT was 13.6% with enoxapa rin (95% confidence interval [CI] 10.9% to 16.3%) and 20.6% with warfa rin (95% CI 17.4% to 23.8%). At a cost of $19.55 per day for enoxapari n the total cost per patient, including prophylaxis and management of DVT, exceeded that per patient receiving warfarin by about $121. For e very 10 000 patients treated the use of enoxaparin will prevent 47 cas es of DVT, 3 cases of PE and 4 deaths. Thus, the estimated incremental cost-effectiveness of enoxaparin is $29 120 per life-year gained. Con clusion: On the basis of current Canadian cost-effectiveness guideline s the results of this study would be considered moderate to strong evi dence to adopt enoxaparin prophylaxis against DVT after total hip repl acement. However, because of the limited data the estimates are uncert ain. Future trials should compare enoxaparin and warfarin and incorpor ate a prospective economic appraisal.