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Treatment of proximal vein thrombosis with subcutaneous low-molecular-weight heparin vs intravenous heparin |
Hull R D, Raskob G E, Rosenbloom D, Pineo G F, Lerner R G, Gafni A, Trowbridge A A, Elliott C G, Green D, Feinglass J, Feldstein W, Brant R |
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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 Using a once daily fixed dose of subcutaneous low-molecular-weight (LMW) heparin or intravenous (IV) heparin given by continuous infusion for the treatment of proximal vein thrombosis.
Economic study type Cost-effectiveness analysis.
Study population Patients with acute proximal deep vein thrombosis.
Setting Hospital. The economic study was carried out in the USA, and Canada.
Dates to which data relate The effectiveness and resource data were derived from a paper reporting the results of a randomised controlled trial carried out by the authors and published in 1992 (New England Journal of Medicine 1992:326; 975-862).1992 prices were used.
Source of effectiveness data The evidence for the final outcomes was derived from a single study.
Link between effectiveness and cost data Costing was undertaken prospectively on the same patient sample as that used in the effectiveness study.
Study sample Power calculations were used to determine the sample size. The study sample consisted of 432 patients, of whom 213 were randomly assigned to the LMW group and 219 to the IV group.
Study design The study was a multicentre randomized controlled trial. Patients were followed up for 3 months.
Analysis of effectiveness It was not stated whether the analysis of the clinical study was based on intention to treat or on treatment completers only. Primary health outcomes were the frequency of recurrent venous thromboembolism, major bleeding complication and death. The groups were shown to be comparable.
Effectiveness results The frequency of recurrent venous thromboembolism was 6.9% for patients receivingadjusted-dose IV heparin and 2.8% for patients receiving LMW heparin therapy (P= 0.07, 95% CI: for the difference = 0.02% - 8.1%). The respective rates of major bleeding complication were 5.0% and 2.8% for IV heparin and low molecular weight heparin respectively. The rate of death in LMW group was 4.7% versus 9.6% in the IV group (P=0.06 by Fisher Exact test and P=0.049 by the uncorrected chi-square test; risk reduction, 51%).
Clinical conclusions The study revealedthat low-molecular-weight heparin was at least as effective and safe as intravenous heparin.
Measure of benefits used in the economic analysis The benefit measures were the frequency of recurrent venous thromboembolism, major bleeding complications and death.
Direct costs Quantities were not reported separately from the costs. The unit cost items were reported separately. The total cost per 100 patients was reported for each health technology (the cost measure was also calculated for a case in which the possible proportion of patients (37%) in the LMW group were treated as outpatients). The treatment costs were divided into the cost of anticoagulant therapy including drugs and laboratory tests, inpatient costs of hospitalization, the cost of treating the illness for 12 months, and the costs of major bleeding complications. The cost analysis was undertaken from a third-party payer's perspective. The sources of cost data were two hospitals, one in Canada and the other in the USA. The costs of clinical examination and documentation were omitted since they were common to both alternatives. Indirect costs, and the costs of minor bleeding episodes and nonhaemorrhagic complications were not considered in the cost calculations. The date to which the price data referred was 1992.
Currency Canadian dollars (Can$) and US dollars ($).
Sensitivity analysis Multiple sensitivity analyses were carried out on a large number of variables involved in the cost calculations including initial drug treatment with either LMW heparin or IV heparin, long-term anticoagulant therapy, pharmacy, laboratory monitoring, an objective diagnosis and treatment of recurrent venous thromboembolism, management of haemorrhagic complications, inpatient costs of hospitalization, and physician input and the number of hospital days. The purpose of the sensitivity analysis was to assess the effects of regional variations in unit costs.
Estimated benefits used in the economic analysis The frequency of recurrent venous thromboembolism was 6.9% for patients receivingadjusted-dose IV heparin and 2.8% for those receiving LMW heparin therapy, (P= 0.07, 95% CI for the difference = 0.02% - 8.1%). The respective rates of major bleeding complication were 5.0% and 2.8% for IV heparin and low molecular weight heparin, respectively. The rate of death in LMW group was 4.7% versus 9.6% in the IV group (P=0.06 by Fisher Exact test and P=0.049 by the uncorrected chi-square test; risk reduction, 51%).
Cost results The total cost per 100 patients treated with intravenous heparin was Can$414,655 ($375,836). The corresponding figure forpatients treated with low-molecular-weight heparin was Can$399,403 ($335,687). The total costs per 100 patients treated with LMW heparin in a case in which 37% of the patients had outpatient therapy would have been Can$318,919 ($284,504).
Synthesis of costs and benefits A synthesis was not undertaken by the authors since the use of LMW heparin was the weakly dominant strategy. The sensitivity analysis established the robustness of the results to a wide range of alterations in the baseline values.
Authors' conclusions The findings indicate that LMW heparin is at least as effective and safe, but less costly than, IV heparin treatment. The potential for outpatient therapy in up to 37% of patients who are receiving LMW heparin would substantially augment the cost saving.
CRD COMMENTARY - Selection of comparators A justification was provided for the choice of the comparator. Intravenous heparin therapy was considered as the gold standard for the treatment of proximal vein thrombosis. You should consider whether this is a widely used health technology in your own setting.
Validity of estimate of measure of benefit The estimates of the benefit measure are likely to be internally valid.
Validity of estimate of costs Resource quantities were not reported separately from the unit costs. Adequate details of the methods of cost calculations were given. Indirect costs were excluded from the study. The authors' conclusion in regard to LMW therapy being a less costly policy was not justified because, in the absence of statistical analysis of the costs, the statistical significance of difference cannot be assessed.
Other issues The authors pointed out that their findings may not be generalisable to other LMW heparin fractions.
Source of funding Supported by a grant from the Heart and Stroke Foundation of Alberta, Calgary and also by Novo Nordisk, Bagsvaerd, Denmark.
Bibliographic details Hull R D, Raskob G E, Rosenbloom D, Pineo G F, Lerner R G, Gafni A, Trowbridge A A, Elliott C G, Green D, Feinglass J, Feldstein W, Brant R. Treatment of proximal vein thrombosis with subcutaneous low-molecular-weight heparin vs intravenous heparin. Archives of Internal Medicine 1997; 157: 289-294 Other publications of related interest Commentary in: ACP Journal Club 1997;127(1):23.
Hull R D, Pineo G F, Raskob G E; The economic impact of treating deep vein thrombosis with low-molecular-weight heparin: outcome of therapy and health economy aspects. Haemostasis 1998;28(suppl 3);pp.8-16
Indexing Status Subject indexing assigned by NLM MeSH Anticoagulants /administration & Bias (Epidemiology); Canada; Cost-Benefit Analysis; Drug Administration Schedule; Heparin /administration & Heparin, Low-Molecular-Weight /administration & Humans; Infusions, Intravenous; Injections, Subcutaneous; Sensitivity and Specificity; Thromboembolism /etiology /prevention & Thrombosis /complications /drug therapy /pathology; United States; control; dosage /economics; dosage /economics; dosage /economics AccessionNumber 21997008060 Date bibliographic record published 31/12/1998 Date abstract record published 31/12/1998 |
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