Source of effectiveness data The evidence for effectiveness was based on a synthesis of previously completed studies.

Transcription

1 Economic evaluation of the use of nadroparin calcium in the prophylaxis of deep vein thrombosis and pulmonary embolism in surgical patients in Italy Lloyd A, Aitken J A, Hoffmeyer U K, Kelso E J, Wakerly E C, Barber N 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 The use of nadroparin calcium (a low-molecular weight heparin (LMWH)) in the prophylaxis of deep vein thrombosis (DVT) and pulmonary embolism (PE). Type of intervention Primary prevention. Economic study type Cost-effectiveness analysis. Study population Patients, in Italy, undergoing orthopaedic surgery (elective or traumatic hip surgery) or major general surgery (abdominothoracic or gynaecological). Setting Hospital. The study was carried out in Italy. Dates to which data relate The effectiveness data were obtained from studies published in 1991 and 1992 (study report and meta-analysis, respectively). The dates to which the resource use data refer were not reported prices were used. Source of effectiveness data The evidence for effectiveness was based on a synthesis of previously completed studies. Modelling A decision tree was used in order to estimate the expected costs associated with each strategy. Outcomes assessed in the review The outcomes assessed were the risk of VTE occurrence (efficacy) and risk of major, clinically significant, bleeding. Study designs and other criteria for inclusion in the review Not stated. Page: 1 / 5

2 Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Not stated. Methods used to judge relevance and validity, and for extracting data Number of primary studies included Four studies were used to obtain parameter estimates for the model, including one meta-analysis of 23 randomised controlled trials. Methods of combining primary studies Not combined. Investigation of differences between primary studies Results of the review The intervention appeared to be more efficacious than the comparator in terms of risk of VTE episodes. The probabilities with UFH prophylaxisand LMWH (figures for general surgery in parentheses) were: symptomatic DVT: UFH (0.064); LMWH (0.059) non-symptomatic DVT: UFH (0.909); LMWH (0.918) symptomatic PE: UFH (0.025); LMWH (0.022) massive PE: UFH (0.002); LMWH (0.001). The risk ratio for bleeding with LMWH relative to UFH after major general surgery was 1.01 (95% CI: ), whereas, after orthopaedic surgery it was 0.75 (95% CI: ). Measure of benefits used in the economic analysis The measure of benefits used in the economic analysis was cases of symptomatic VTE (either pulmonary embolism or deep vein thrombosis) prevented. This definition of outcome differed from that reported in most clinical studies, since clinically detected VTE includes both symptomatic and asymptomatic cases. The treatment decision in general practice in Italy is based on symptomatic cases only. A 35% rate of symptomatic cases (from one-hundred percent of objectively-detected cases) was used in the analysis. Direct costs The resource quantities were not reported separately from costs. The costs measured were operating costs (prophylaxis, screening and treatment of VTE). The costs boundary adopted was the hospital. The estimation of resource use and costs was based mainly on experts' opinions. The amount of time of prophylaxis and treatment with heparin was based on actual data from a general hospital in Milan, Italy. The (unit) costs were obtained from Italian 'list prices', the San Carlo Borromeo General Hospital in Milan and manufacturers' prices. The prices used were from Costs of major Page: 2 / 5

3 bleeding (complications) were excluded as they were considered to be common. Currency Italian lire (L). The exchange rate reported (1994) was $US 1=L 1600 (approx). Sensitivity analysis The parameters explored in the sensitivity analysis were the duration of prophylaxis, frequency of dosage per day for the comparator, duration of treatment and treatment costs, duration of additional hospital stay, and relative risk of VTE. In addition, the assumption of empirical treatment (based on symptoms rather than diagnostic procedures) was introduced. One-way and multi-way sensitivity analyses were performed. Estimated benefits used in the economic analysis The expected number of cases of DVT for a hypothetical cohort of 1,000 patients undergoingorthopaedic surgery with the comparator was 74, whereas the corresponding figure for the intervention was 48. The values for PE occurrence were 41 and 17, respectively. The expected number of cases of DVT for a hypothetical cohort of 1000 patients undergoing major general surgery with the comparator was 24, whereas the corresponding figure for the intervention was 19. The values for PE occurrence were 7 and 3, respectively. Cost results The expected costs of managing VTE per patient undergoing orthopaedic surgery were: DVT: intervention L179,340; comparator L274,102 PE: intervention L12,9723; comparator L308,588 For patients undergoing major general surgery the costs were: DVT: intervention L69,822; comparator L88,251 PE: intervention L27,853; comparator L56,710 For patients undergoing orthopaedic surgery, prophylaxis with nadroparin calcium reduced costs by L267,226 compared to UFH, and for general surgery patients the cost savings were L45,588. The main result from the sensitivity analysis was that the price of 0.3 ml pre-filled nadroparin calcium syringe would have to increase by more than 250% and 700%, for major general and orthopaedic surgery patients, respectively, in order for the expected costs of nadroparin calcium prophylaxis to exceed those of UFH prophylaxis. The results were not sensitive to the incidence rate of VTE. Synthesis of costs and benefits The costs and benefits associated with each strategy were not combined since the intervention was shown to be the dominant strategy (i.e. it showed lower expected costs and more favourable health outcomes). Authors' conclusions The authors concluded that nadroparin calcium (LMWH), used instead of UFH in the prophylaxis of VTE, reduced the costs of managing VTE. CRD COMMENTARY - Selection of comparators A justification was given for the comparator used. The comparator chosen was unfractionated heparin (UFH), in prophylaxis of VTE, at a dose of 5,000 units administered 3 times per day for a period of 6 days, in patients undergoing Page: 3 / 5

4 major general surgery, and for a period of 8 days in patients undergoing orthopaedic surgery. UFH was chosen as a comparator because the newer LMWHs are derived from this traditionally used form of heparin. You, as a user of this database, should consider whether this is a widely used technology in your own setting. Validity of estimate of measure of benefit The effectiveness estimation was derived from a set of assumptions based on a non-systematic review of the literature, and hence, may be subject to bias. The key efficacy estimates, however, were derived from a previously published metaanalysis of 23 randomised controlled trials, which is more likely to produce objective and unbiased estimates. The authors also investigated the potential effects of parameter changes on the final results using a sensitivity analysis. The data were not used to prove any particular point. Validity of estimate of costs The resource quantities used were not reported separately from the costs. The details of the cost estimation were provided, and the model used for the final expected cost estimate was obtained from a "European consensus statement". The estimation of resource use and costs was based on experts' opinions. The costs associated with complications (i.e. major bleeding) were excluded from the analysis after finding a similar risk between strategies. In addition, long-term complication costs and travel expenses by patients were not included due to lack of data. Other issues The conclusions reached seem to be justified. The sensitivity analysis demonstrated the robustness of the results to changes in several of the model parameters. This study was carried out with the purpose of determining whether results in other health care systems (payers' perspective) could be extended to the setting relevant for Italy. It was not quite clear, however, how the results of the study compared with those in other settings. The results were not presented selectively. Source of funding Funded by Sanofi Winthrop SpA and Italfarmaco SpA. Bibliographic details Lloyd A, Aitken J A, Hoffmeyer U K, Kelso E J, Wakerly E C, Barber N D. Economic evaluation of the use of nadroparin calcium in the prophylaxis of deep vein thrombosis and pulmonary embolism in surgical patients in Italy. PharmacoEconomics 1997; 12(4): PubMedID Indexing Status Subject indexing assigned by NLM MeSH Fibrinolytic Agents /economics /therapeutic use; Humans; Italy; Nadroparin /economics /therapeutic use; Postoperative Complications /economics /prevention & control; Pulmonary Embolism /economics /prevention & control; Thrombophlebitis /economics /prevention & control AccessionNumber Date bibliographic record published 31/12/1998 Page: 4 / 5

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