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Cost effectiveness of micronised fenofibrate and simvastatin in the short term treatment of type IIa and type IIb hyperlipidaemia |
Kirchgassler K U, Schiffner-Rohe J, Stahlheber U |
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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 Micronised Fenofibrate and Simvastatin in the treatment of type IIa and IIb hyperlipidaemia.
Type of intervention Treatment; Secondary prevention.
Economic study type Cost-effectiveness analysis.
Study population Patients (median age 51 years) with type IIa hyperlipidaemia (low density lipoprotein (LDL) cholesterol levels >= 160 mg and triglyceride levels lower than 200 mg) and type IIb hyperlipidaemia (LDL cholesterol levels >= 160 mg and triglyceride levels above 200 mg) defined according to Frederickson's classification.
Setting Primary care. The studies from which the clinical data were drawn were carried out in France and Germany.
Dates to which data relate The effectiveness data and resource use quantities were obtained from two studies published in 1996 and 1994. The prices used were from 1995.
Source of effectiveness data The evidence for effectiveness was based on a synthesis of previously completed studies.
Modelling A decision tree was used to estimate expected average costs. Each treatment arm included the probability of occurrence of adverse events and the probabilities of study termination or continuation.
Outcomes assessed in the review The outcomes assessed in the review were the response rates, probabilities of occurrence/no occurrence of adverse events and of continuation/discontinuation of therapy for each treatment arm, for each of the types of hyperlipidaemia, both combined and analysed separately.
Study designs and other criteria for inclusion in the review The authors reported that the analysis considered "all trials available at the data lock point".
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 The judgement criteria for relevance and validity used by the authors were not reported. The original data used in the studies were extracted.
Number of primary studies included Two primary studies were included in the analysis. One single-centre randomised controlled trial and one multi-centre randomised controlled trial.
Methods of combining primary studies Meta-analysis was undertaken by pooling original raw data from the two primary studies.
Investigation of differences between primary studies The French study had a crossover design with a duration of 12 weeks per treatment. In order to maximise comparability of treatments, the authors used only data from the first treatment period.
Results of the review The probabilities of an adverse event with micronised fenofibrate for type IIa, type IIb, and both types combined were 0.14, 0.20, and 0.16, respectively. The corresponding probability values for simvastatin were 0.16, 0.19 and 0.18. The probability values of study termination with an adverse eventwere, for micronised fenofibrate, 0.13, 0.00, and 0.07, for type IIa, type IIb, and both types combined, respectively. The corresponding values for the study termination without an adverse event in the micronised fenofibrate arm were 0.04, 0.08, and 0.05, respectively. The probabilities of patients in the simvastatin group withdrawing from therapy due to adverse events were 0.00, 0.29, and 0.13, in the case of type IIa, IIb, and both types combined, respectively. The corresponding values for withdrawal from the study without adverse event occurrence in the simvastatin group were 0.02, 0.07, and 0.04, respectively. The response rate of simvastatin 20 mg in patients with type IIa hyperlipidaemia was 98%, against 78% with micronised fenofibrate 200 mg for the same patient group. For the type IIb patient group, the response rates were 31% and 57%, respectively.
Measure of benefits used in the economic analysis The number of responders for a given number of patients (response rate) was the measure of benefits used in the economic analysis. The original response criteria were determined as a 15% decrease in LDL cholesterol for patients with type IIa hyperlipidaemia, and a 15% decrease in LDL cholesterol in combination with a 30% decrease in triglycerides for type IIb patients.
Direct costs The resource quantities were not reported separately from costs. The costs measured were operating costs and costs of complications. The boundary adopted was that of the health services. The estimation of most quantities was based on actual data from both clinical trials and the unit costs for medications were mainly based on the German National Formulary, this source being complemented by the French National Formulary. The costs of visits to the physician and routine examinations were excluded from the analysis because they were found, in the opinion of experts, to be common to both drug regimens. Also, the protocol related costs were excluded.
Currency German marks (DM). The reported exchange rate for April 1995 was DM1=US$0.66.
Sensitivity analysis The response rates and costs were varied in the sensitivity analysis, and a separate analysis was carried out based on data from two drug-monitoring programmes of micronised fenofibrate of 3 months duration. In addition, two different response criteria were analysed. A best-worst case scenario was used in the analysis. One-way and multi-way sensitivity analyses were performed. Monte Carlo simulation was used to analyse the asymptotic behaviour of the final estimates.
Estimated benefits used in the economic analysis The response rate of simvastatin 20 mg in patients with type IIa hyperlipidaemia was 98%, against 78% with micronised fenofibrate 200 mg for the same patient group. For the type IIb patient group, the response rates were 31% and 57%, respectively. The overall response rates (both types combined) were 69.4% and 70.5%, respectively.
Cost results The expected cost of treatment per patient for simvastatin was DM 561, and that for micronised fenofibrate was DM 378.
Synthesis of costs and benefits The measure used in the synthesis of costs and benefits was the expected cost per responder in DM at 1995 prices. The cost per responder for simvastatin was DM 809 and for micronised fenofibrate was DM 537. The corresponding figures were DM 517 and DM 450, and DM 2080 and DM 768 for patients with type IIa , and type IIb hyperlipidaemia, respectively. The sensitivity analysis yielded the same results for micronised fenofibrate once the data from the drug-monitoring programmes were included. An exception was the worst case scenario, which was justified by the authors by noting the presence of outliers. The superiority of micronised fenofibrate over simvastatin in terms of cost-effectiveness was reported to hold in all cases tested except when the response criteria were changed. In this case, simvastatin had an expected cost per responder of DM 1,760, against DM 2,178 for micronised fenofibrate in patients with coronary heart disease with type IIb hyperlipidaemia and the response criterion defined as less than 115 mg/dl.
Authors' conclusions The authors concluded that, in terms of short term cost-effectiveness, micronised fenofibrate 200 mg was superior to simvastatin 20 mg, with this result being stronger for type IIb hyperlipidaemia patients. They went on to suggest that, in view of the large difference in cost of therapy between micronised fenofibrate and simvastatin, consideration should be given, in patients with type IIa hyperlipidaemia, to beginning therapy with micronised fenofibrate, and then switching to simvastatin in cases of insufficient response.
CRD COMMENTARY - Selection of comparators The strategies compared were examples of the most widely used types of technology for the treatment of hyperlipidaemia. You, as a user of this database, should consider whether these are widely used health technologies in your own setting.
Validity of estimate of measure of benefit The study was based on an overview and synthesis of two randomized controlled trials. However, the trials provided data for up to 12 weeks and, therefore, used a short-term outcome measure (response rate), which may not be an accurate representation of effectiveness (CHD risk). The authors did not discuss the differences between the primary studies and how they might affect the final results. The data have not been used selectively to prove any particular point.
Validity of estimate of costs The resource quantities were not reported separately from the costs. Adequate details of cost estimation were given. Protocol driven costs (e.g. laboratory tests) were excluded due to differences in tests performed between the primary studies included in the analysis. Furthermore, based on experts' opinion, the costs associated with visits to the physician and routine examinations were excluded from the analysis because they were determined to be common.
Other issues The conclusions were justified. An extensive sensitivity analysis and a Monte Carlo simulation were performed to address the uncertainties related to the data. However, the study does not provide evidence for the long term cost-effectiveness. The results may not be generalisable to other countries than Germany and France from where the resource use and price data were obtained. The sensitivity analysis of the results was presented only for a combination of both types of hyperlipidaemia.
Bibliographic details Kirchgassler K U, Schiffner-Rohe J, Stahlheber U. Cost effectiveness of micronised fenofibrate and simvastatin in the short term treatment of type IIa and type IIb hyperlipidaemia. PharmacoEconomics 1997; 12(2): 237-246 Indexing Status Subject indexing assigned by NLM MeSH Anticholesteremic Agents /administration & Double-Blind Method; Female; Fenofibrate /administration & Humans; Hyperlipoproteinemia Type II /drug therapy /economics; Hypolipidemic Agents /administration & Lovastatin /administration & Male; Middle Aged; Retrospective Studies; Simvastatin; derivatives /economics /therapeutic use; dosage /analogs & dosage /economics /therapeutic use; dosage /economics /therapeutic use; dosage /economics /therapeutic use AccessionNumber 21997008285 Date bibliographic record published 31/12/1998 Date abstract record published 31/12/1998 |
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