Study population The study population comprised patients undergoing major hip or knee surgery.

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1 Pharmacoeconomic analysis of fondaparinux versus enoxaparin for the prevention of thromboembolic events in orthopedic surgery patients Dranitsaris G, Kahn S R, Stumpo C, Paton T W, Martineau J, Smith R, Ginsberg J S Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology This study considered the use of fondaparinux, a synthetic antithrombotic, administered 6 hours after surgery for 7 days, for the prevention of thromboembolic events following orthopaedic surgery. Type of intervention Primary prevention. Economic study type Cost-effectiveness analysis. Study population The study population comprised patients undergoing major hip or knee surgery. Setting The setting was secondary care. The economic study was carried out in Canada. Dates to which data relate The effectiveness data were taken from papers published between 2001 and The dates of the resource use data and the price year were not reported. Source of effectiveness data The effectiveness data were derived from a review or synthesis of completed studies. Modelling A cohort deterministic model was used to model the clinical and economic implications of using fondaparinux versus enoxaparin to prevent thromboembolic events following major orthopaedic surgery. The cohort studied was the cohort of patients undergoing major hip or knee surgery in Canada during 1999 and Outcomes assessed in the review The absolute risks of a venous thromboembolism (VTE) in patients treated with fondaparinux and those treated with enoxaparin were identified. Study designs and other criteria for inclusion in the review This paper did not list the criteria used to identify papers to provide the model parameters. However, it was indicated Page: 1 / 5

2 that the published paper used was a meta-analysis of four randomised controlled trials (Turpie et al. 2002, see 'Other Publications of Related Interest' below for bibliographic details). Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included The model parameters were identified from one published paper. Methods of combining primary studies The published paper used to identify model parameters was a meta-analysis of four randomised controlled trials. Investigation of differences between primary studies Results of the review The meta-analysis identified a 6.8% absolute risk of a VTE by day 11 postoperatively for patients treated with fondaparinux, compared with an absolute risk of 13.7% for those treated with enoxaparin. This equates to a relative odds reduction of 55.2% (95% confidence interval: ) in favour of fondaparinux, (p<0.001). Measure of benefits used in the economic analysis The measures of health benefit used were the number of deep vein thromboses (DVT) and pulmonary emboli (PE) prevented in each of the patient groups. Direct costs The costs of the Canadian health system were identified in the analysis. Individual level resource use data were taken from a survey of four Canadian centres. This was then extrapolated to the study population (the cohort of Canadian patients undergoing hip or knee surgery in 1999/2000) using the model outlined already. The unit costs of fondaparinux and enoxaparin were obtained from the manufacturer. The costs of warfarin, drug administration, nursing and diagnostic tests (excluding ultrasound) were taken from the University Health Network. The costs of ultrasound diagnostic tests were taken from the Capital Health Region, British Columbia. The Ontario Hospital Association provided the cost of each day in hospital, while the cost of physician assessments and visits were taken from the schedule of benefits, Ontario. Resource use and unit costs were identified separately in the paper. No clear price year was identified, although the paper indicated that some unit costs related to Statistical analysis of costs The cost data were treated deterministically. Page: 2 / 5

3 Indirect Costs No indirect costs were included in the study. Currency Canadian dollars (Can$). Sensitivity analysis Several one-way sensitivity analyses were used to investigate the impact of variability in the data. The ranges used to consider the impact of variability in the effectiveness of the two treatments were taken from the confidence intervals for the relative risks. Variations in the cost data were based on the upper and lower ranges reported in the survey of clinicians. Estimated benefits used in the economic analysis In the 20,036 patients undergoing total hip replacement, 138 DVTs and 82 PEs would be prevented in the first 90 days postoperatively with the use of fondaparinux rather than enoxaparin. A total of 284 DVTs and 120 PEs would be avoided with the use of fondaparinux rather than enoxaparin in total knee replacement patients. In the 8,353 patients undergoing hip fracture surgery, the use of fondaparinux rather than enoxaparin would avoid 116 DVTs and 73 PEs. Cost results The mean cost of treatment with fondaparinux would be Can$228 per patient, compared with Can$283 for patients treated with enoxaparin. All of the sensitivity analyses confirmed that fondaparinux was cost-saving in comparison with enoxaparin. Synthesis of costs and benefits The costs and effectiveness were not combined. Authors' conclusions In a Canadian setting, prophylactic treatment with fondaparinux rather than enoxaparin avoided venous thromboembolic events and was cost-saving. CRD COMMENTARY - Selection of comparators This study compared prophylactic treatment with fondaparinux and enoxaparin (a low molecular weight heparin) for the preventions of venous thromboembolic events. No explicit reason for this comparator was given, but the authors reported that low molecular weight heparins are widely used. You should consider how this relates to current practice in your own setting before applying the results of this study. Validity of estimate of measure of effectiveness The measure of effectiveness was modelled using a cohort deterministic model. The model parameters were obtained from a published meta-analysis of four randomised controlled trials. The methods used to identify this meta-analysis and any quality criteria applied were not reported, thus it is not possible to comment on whether the search methods lead to a potential for bias. Page: 3 / 5

4 Validity of estimate of measure of benefit The model produced two outcome measures to compare the effectiveness of the interventions. However, no summary measure of health benefit was synthesised with the costs. In effect, the study was a cost-consequences analysis. Validity of estimate of costs The cost perspective of the study was the Canadian health service. As such, all the appropriate costs appear to have been included. Several one-way sensitivity analyses were conducted to assess uncertainty and variability in the unit cost and resource use data. The ranges used were taken from appropriate sources. A clear breakdown of resource use and units costs was provided. These factors increase the generalisability of the study findings. Unfortunately, no clear price year was reported in the paper and this will limit any future reflation exercises. Other issues The authors presented their results in a comprehensive manner and their conclusions reflected the scope of their analysis. They compared their results with other studies that had used the same model in other patient populations. The study was specific to the Canadian setting, therefore the scope to generalise the study findings to other countries was not considered. The authors acknowledged that their study was limited by the fact that they used modelled data rather than information taken directly from a randomised controlled trial. They suggested that a Markov model, rather than a cohort deterministic model, would have provided a more robust estimate of the impact of these treatments. Implications of the study The authors did not make any specific recommendations for changes in policy or further research. Source of funding Funded by an unrestricted grant-in-aid from Sanofi Synthelabo, Canada. Bibliographic details Dranitsaris G, Kahn S R, Stumpo C, Paton T W, Martineau J, Smith R, Ginsberg J S. Pharmacoeconomic analysis of fondaparinux versus enoxaparin for the prevention of thromboembolic events in orthopedic surgery patients. American Journal of Cardiovascular Drugs 2004; 4(5): PubMedID Other publications of related interest Turpie AG, Bauer, KA, Eriksson BI, et al. Fondaparinux vs enoxaparin for the prevention of venous thromboembolism in major orthopaedic surgery: a meta-analysis of 4 randomised double blind studies. Arch Intern Med 2002;262: Indexing Status Subject indexing assigned by NLM MeSH Anticoagulants /administration & dosage /classification /economics /therapeutic use; Arthroplasty, Replacement, Hip /adverse effects /economics; Arthroplasty, Replacement, Knee /adverse effects /economics; Canada /epidemiology; Cost-Benefit Analysis; Economics, Pharmaceutical; Enoxaparin /administration & dosage /economics /therapeutic use; Hospital Costs /statistics & numerical data; Humans; Models, Econometric; Orthopedic Procedures /adverse effects; Polysaccharides /administration & dosage /economics /therapeutic use; Randomized Controlled Trials as Topic; Safety; Thromboembolism /epidemiology /prevention & control Page: 4 / 5

5 Powered by TCPDF ( AccessionNumber Date bibliographic record published 28/02/2006 Date abstract record published 28/02/2006 Page: 5 / 5