|
Economic evaluation of desirudin vs heparin in deep vein thrombosis prevention after hip replacement surgery |
Levin L, Horst M, Bergqvist D |
|
|
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 Prophylactic treatment against deep vein thrombosis (DVT) following orthopaedic surgery using selective inhibitors of human thrombin, specifically desirudin 15mg twice daily and unfractionated heparin 5000IU 3 times daily.
Economic study type Cost-effectiveness analysis.
Study population Patients between the ages of 18 and 85, weighing more than 50kg, and undergoing elective orthopaedic surgery. The mean age of hypothetical patients was 68 years of age.
Setting Hospital. The economic analysis was conducted in Linkoping, Sweden.
Dates to which data relate Effectiveness and resource data were taken from studies previously published in 1987, 1994, 1995 and 1997. 1995 price years appear to have been used, although this was not clearly stated.
Source of effectiveness data Effectiveness data were derived from a review of previously completed studies.
Modelling A decision tree simulation model was used to combine information identified from previous publications on the clinical effectiveness, probabilities of detection of DVT and mortality data relating to the two treatment options with information on the costs of treatment and associated long term consequences in order to identify costs per life year gained. Markov iterations were used to incorporate annual mortality and the risk of long term complications. The mean age of patients in the model was 68 and iterations of the model were run for hypothetical patients until they reached 85 years of age.
Outcomes assessed in the review Efficacy of unfractionated heparin, desirudin and other prophylaxis against DVT and probabilities of detecting DVT, dying from DVT, developing a pulmonary embolism (PE) following DVT, sudden death from a PE, detection of PE, dying from detected and treated PE, dying from non-detected PE, and probabilities of false positive diagnoses.
Study designs and other criteria for inclusion in the review 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 One multicentre randomised controlled trial, and one economic evaluation examining prophylaxis for DVT following surgery were included in the review.
Methods of combining primary studies Both studies had separate inputs in the analysis.
Investigation of differences between primary studies Results of the review The probabilities identified in the review were as follows:
DVT rate using desirudin 0.075;
DVT rate using unfractionated heparin 0.232;
probabilities of detecting DVT 0.162;
dying from DVT 0.006;
developing a pulmonary embolism (PE) if patient has DVT 0.1145;
sudden death from a PE 0.110;
detection of PE 0.290;
dying from detected and treated PE 0.080;
dying from non detected PE 0.300;
false positive diagnosis of DVT 0.044;
false positive diagnosis of PE 0.020.
Measure of benefits used in the economic analysis The benefit measure was life years gained. Benefits were discounted at a rate of 5% per annum.
Direct costs The costs of treatment, hospital stay, diagnostic procedures and complications were included in the analysis. Costs for treatment for DVT and pulmonary embolisms, hospital stay and diagnostic procedures were taken from a 1994 Swedish publication. Costs of unfractionated heparin were taken from the 1995 Swedish pharmacy price list. Costs of desirudin were not available as the drug had not, as yet, been marketed. The costs of long term consequences of DVT were taken from a 1997 Swedish cost-effectiveness analysis. Costs were determined from the perspective of a third party payer and were discounted at a rate of 5% per annum. 1995 base price years appear to have been used.
Sensitivity analysis A number of parameters were varied in one-way sensitivity analysis to account for uncertainty in the model. These parameters included discount rates for both costs and benefits, cost of heparin, inclusion of long term complications, mortality risks etc.
Estimated benefits used in the economic analysis 4.5 incremental life years were gained per 100 patients using desirudin compared with patients treated with unfractionated heparin.
Cost results The mean cost per patient for treatment of DVT using unfractionated heparin was SEK 6,470, compared with a mean cost per patient of SEK 2,070 for patients receiving desirudin (not including direct costs of desirudin prophylaxis).
Synthesis of costs and benefits If the cost of desirudin prophylaxis were SEK4,400 or less, then the intervention would be dominant over unfractionated heparin treatment.
Authors' conclusions Desirudin would improve patient outcomes, and also reduce costs of treatment compared with unfractionated heparin treatment for DVT, if costs of desirudin prophylaxis were no more than SEK4,400 per patient. The results were robust in sensitivity analysis.
CRD COMMENTARY - Selection of comparators A justification was provided by the authors for the comparator used, unfractionated heparin. This is a standard, widely used regimen against DVT. As noted by the authors, future economic analyses would also consider the intervention compared with low molecular weight heparin.
Validity of estimate of measure of benefit Benefits were modelled using data from one clinical trial and an economic evaluation of prophylaxis for DVT. It is not clear how the authors identified these sources of data, and this may make the analysis prone to bias. It would also have been helpful had the authors indicated whether there have been any other clinical trials published for desirudin.
Validity of estimate of costs Costs and resources used were principally identified from previously published estimates. Only direct costs were considered in the analysis, and future studies should also consider other costs, such as those to society. It is not entirely clear whether a 1995 base price year was used for the estimate of the costs of long term complications of deep vein thrombosis.
Other issues The estimates of costs and resources used in the analysis may not be generalisable outside the Swedish healthcare system.
Implications of the study There is a need for well designed prospective economic evaluations to compare desirudin with other appropriate comparators in the treatment of DVT and prevention of pulmonary embolisms.
Source of funding Funded by Ciba-Geigy AG, Basle, Switzerland.
Bibliographic details Levin L, Horst M, Bergqvist D. Economic evaluation of desirudin vs heparin in deep vein thrombosis prevention after hip replacement surgery. PharmacoEconomics 1998; 13(1 Part 2): 111-118 Indexing Status Subject indexing assigned by NLM MeSH Anticoagulants /economics /therapeutic use; Arthroplasty, Replacement, Hip /adverse effects /economics; Clinical Trials as Topic; Cost-Benefit Analysis; Heparin /economics /therapeutic use; Hirudin Therapy; Hirudins /analogs & Humans; Models, Economic; Recombinant Proteins /economics /therapeutic use; Sweden; Thrombosis /economics /prevention & control; derivatives /economics AccessionNumber 21998008025 Date bibliographic record published 30/04/2000 Date abstract record published 30/04/2000 |
|
|
|