01-09-2005 | Original Research Article
Cost effectiveness of dalteparin for preventing venous thromboembolism in abdominal surgery
Published in: PharmacoEconomics | Issue 9/2005
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Introduction: Patients undergoing abdominal surgeries face substantial risk of experiencing venous thromboembolic events in the perioperative period. The low-molecular-weight heparin dalteparin sodium is clinically effective in reducing the incidence of venous thromboembolism (VTE) in these patients. Dalteparin may be used in low (2500 units [U]) and high (5000U) once-daily doses for this indication. However, the cost effectiveness of dalteparin 5000U compared with dalteparin 2500U and unfractionated heparin (UFH) for this indication has not been studied.
Objective: To conduct a cost-utility analysis to evaluate the cost effectiveness of dalteparin compared with UFH for preventing VTE in patients undergoing elective abdominal surgery.
Methods: A Markov model, from a healthcare perspective, was constructed to evaluate the cost effectiveness of dalteparin 5000U and dalteparin 2500U compared with UFH. A 69-year-old mixed sex patient population was studied using pooled probabilities of clinical outcomes from randomised, controlled trials. Cost data were mostly derived from Medicare reimbursement, in year 2002–03 values. Cost effectiveness was measured as cost per QALY gained over the patient’s lifetime.
Results: Total costs for patients given UFH, dalteparin 2500U and dalteparin 5000U were $US45 855, $US45 882 and $US46 308, respectively, while QALYs were 9.5603, 9.5632 and 9.5811, respectively. Hence, the incremental cost effectiveness of dalteparin 5000U over dalteparin 2500U and UFH was $US23 799/QALY and $US21 779/QALY gained, respectively. Similarly, cost effectiveness for dalteparin 2500U over UFH was $US9310/QALY gained. Univariate sensitivity analysis showed that dalteparin 5000U maintained its cost effectiveness (incremental cost-effectiveness ratio [ICER] <$US50 000/QALY gained) over the other two regimens for a wide range of cost and effectiveness estimates. Acceptability curves based on the results of Monte Carlo simulation (50 000 patients) showed that dalteparin 5000U would achieve cost effectiveness for 90% of patients at values close to $US230 000/QALY. Dalteparin 2500U was less effective than UFH for patients aged <63 years.
Conclusion: Even though our base-case analysis seems to show that dalteparin 5000U is cost effective compared with dalteparin 2500U and UFH for prophylaxis of VTE in patients undergoing abdominal surgery, Monte Carlo simulation demonstrated that this was the case for only about 50% of the patients if the threshold for cost effectiveness is set at $US50 000 per QALY gained. Furthermore, there was substantial uncertainty in the cost-effectiveness results. To ensure that ≥90% patients receive the benefit of the medication, policy makers would need to commit substantially more resources than suggested by the baseline ICERs.