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Cost-effectiveness analysis of ramipril in heart failure after myocardial infarction: economic evaluation of the Acute Infarction Ramipril Efficacy (AIRE) Study for Germany from the perspective of statutory health insurance |
Schadlich P K, Huppertz E, Brecht J G |
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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 The use of ACE inhibitors in patients following myocardial infarction.
Economic study type Cost-effectiveness analysis.
Study population Patients with evidence of heart failure following myocardial infarction.
Setting Hospital. The economic analysis was conducted in Hamburg, Germany.
Dates to which data relate Data on effectiveness and resources used were taken from a study published in 1993. In addition further resource use information was determined by an expert panel.
Source of effectiveness data Effectiveness data were taken from a single study. 1993 and 1995 prices were used for different elements of the analysis.
Link between effectiveness and cost data Costing was undertaken retrospectively and did not use the same patient sample as in the effectiveness study.
Study sample 2,006 patients with a mean age of 65 years, from 144 study centres were included in the Acute Infarction Ramipril Efficacy (AIRE) study and were randomly allocated to either a placebo group or the ramipril group. There were 992 patients in the placebo group and 1,014 in the ramipril group. It is not clear if power calculations were used to determine the sample size.
Study design The study was a multi-centre, multi-national, double-blinded randomised controlled trial. The method of randomisation used was not stated. The duration of follow up was to the end of the treatment course, which ranged from 6 months to 3.8 years, with an average of 15 months. Overall 20 patients (1%) were lost to follow up.
Analysis of effectiveness The analysis was based on treatment completers only. The primary health outcomes used were the rate of mortality and reduction of incidence of secondary events.
Effectiveness results Ramipril was found to lead to a significant reduction in the rate of mortality compared with patients in the placebo group. The relative reduction in all cause mortality was 27% (95% CI: 11 - 40%; p=0.002). The relative risk reduction of all secondary events (including death, severe/resistant heart failure/myocardial infarction and stroke) was 19% for ramipril (95% CI: 5 - 31%; p = 0.008).
Clinical conclusions Ramipril is an effective therapy in the treatment of patients with signs of heart failure following myocardial infarction.
Modelling Modelling was used to estimate the incremental cost effectiveness ratio for ramipril.
Measure of benefits used in the economic analysis The measure of benefits used was life years gained (LYGs).
Direct costs The direct medical treatment costs related to the acquisition of ramipril and inpatient/outpatient treatment of one episode of heart failure were estimated. All costs were estimated from the perspective of the statutory health insurers in Germany. The price of ramipril was derived from a national pricing list and its cost was determined by calculating daily dose on discharge, and including co-payments from patients for prescription charges and the 5% discount which pharmacies must grant the statutory health insurance funds. Information on lengths of stay due to heart failure was taken from the weighted mean of statistics from the local sickness funds. Information on the cost per treatment day in hospital was taken from the official statistics of the Federal Statistical Office. Some resource use was also estimated by a panel of experts. Costs were discounted at a rate of 5% per annum. Costs for adverse events such as strokes and reinfarction were excluded as no difference in these events between the two study groups had been observed in the AIRE study. 1995 prices were used for drug costs and outpatient medical services. 1993 prices were used for inpatient treatment.
Statistical analysis of costs A Monte Carlo simulation model was used to compare the distribution costs between the ramipril and placebo groups and also to measure the variance in the incremental cost-effectiveness ratios.
Sensitivity analysis Probabilistic sensitivity analysis was used to examine the relationship between cost-effectiveness and a range of independent variables within the model including the incremental cost of ramipril, length of stay, cost for admissions due to heart failure, hospitalisation impact of adding ramipril to conventional therapy, the hospitalisation rate, number of life years gained and the discount rate.
Estimated benefits used in the economic analysis In the first year of treatment there was an increase of 0.027 life years gained (LYG) in the ramipril group when the proportion of patient time spent on ramipril was 69%. Due to deaths and withdrawals, by the end of year 2, LYGs had increased to 0.090 but the proportion of patient time had decreased to 53%. Similarly at the end of year 3, LYGs were 0.170 and patient time was 41% and by the end of 3.8 years, LYGs were 0.289 and patient time had decreased to 25%.
Cost results The total treatment costs for inpatient treatment and additional outpatient medical services ranged from DM6,743 to DM15,547 with a mean of DM9,136. The mean cost for ramipril for 1 patient per year was DM946 (minimum 914, maximum 992) and the mean costs for inpatient treatment of one episode of decompensated heart failure was DM8,882 (minimum 6,633, maximum 15,028). Outpatient medical services mean cost per directly linked admission was 314 (minimum 110, maximum 519).
Synthesis of costs and benefits The incremental cost per life year gained at the end of year 1 was DM8,271 (lower limit -3,712, upper limit 13,624);
at the end of year 2 this was DM4,012 (LL -2,402, UL 6,863);
at the end of year 3 this was DM5,056 (LL 2,203 , UL 6,438);
after 3.8 years the incremental cost per life year gained was DM2,456 (LL -102, UL 3,623).
Sensitivity analysis demonstrated that the model was robust to changes in parameters.
Authors' conclusions The authors concluded that the addition of ramipril to conventional therapy at a cost of DM2,500 per life year gained was favourable from the perspective of the German statutory health insurance system.
CRD COMMENTARY - Selection of comparators Ramipril was compared with standard conventional care for patients with heart failure following myocardial infarction.
Validity of estimate of measure of benefit The estimate of benefit was derived from a large multi-centre multi-national randomised blinded controlled trial which ran for almost four years which should reduce any potential bias.
Validity of estimate of costs Adequate details were given of the sources of costs and resources used, although it is not clear why the authors used two different base price years (1993 and 1995) for different elements of costs. In addition resources usedwere not linked to the clinical data but were determined partly in consultation with a group of experts. Only direct medical costs were included in the analysis and costs to others in society have been excluded. The authors claimed that there is no need to include indirect costs as the average age of presenting patients in Germany is over the retirement age, and hence there would be no productivity losses. However, in addition to paid labour, there are also household production losses which may be significant and would be incurred due to mortality, whilst the amount of informal care provided by family members may increase as a result of an improvement in survival.
Other issues The cost data are not generalisable beyond the German statutory health insurance system.
Implications of the study There is a need for well designed economic evaluations to consider both the direct and indirect costs associated with the use of ramipril and also to identify costs and resource use in a number of different settings and scenarios.
Source of funding Funded by Hoechst Marion Roussel Germany, Hoechst AG.
Bibliographic details Schadlich P K, Huppertz E, Brecht J G. Cost-effectiveness analysis of ramipril in heart failure after myocardial infarction: economic evaluation of the Acute Infarction Ramipril Efficacy (AIRE) Study for Germany from the perspective of statutory health insurance. PharmacoEconomics 1998; 14(6): 653-669 Other publications of related interest The Acute Infarction Ramipril Efficacy (AIRE) Study Investigation. Effect of ramipril on mortality and morbidity of survivors of acute myocardial infarction with clinical evidence of heart failure. Lancet 1993;342:821-828.
Indexing Status Subject indexing assigned by NLM MeSH Angiotensin-Converting Enzyme Inhibitors /economics /therapeutic use; Cost-Benefit Analysis; Germany; Heart Failure /drug therapy /economics /mortality; Humans; Models, Economic; Myocardial Infarction /complications; Outpatients; Patient Admission; Ramipril /economics /therapeutic use; Retrospective Studies AccessionNumber 21999008010 Date bibliographic record published 31/03/1999 Date abstract record published 31/03/1999 |
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