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Cost-effectiveness of different ACE inhibitor treatment scenarios post-myocardial infarction |
McMurray J J, McGuire A, Davie A P, Hughes D |
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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 Angiotensin Converting Enzyme (ACE) inhibitor treatment scenarios post-myocardial infarction.
Economic study type Cost-effectiveness analysis.
Study population Patients suitable for ACE inhibitor treatment after myocardial infarction.
Setting Hospital. The economic study was carried out in London, UK.
Dates to which data relate The main effectiveness data were taken from previously completed studies conducted between 1988 and 1995. Resource and cost data were mainly derived from 1994-95 sources. Resources were measured in 1994-95 values. The price year was 1994.
Source of effectiveness data Estimates of the number of patients who fulfilled AIRE and SAVE type criteria, rates of revascularization, myocardial infarction and hospitalization for heart failurewere derived from reviews of previous studies.
Modelling A model was used to predict the 4-year mortality, life years gained and costs of each treatment strategy. The model's output was incremental cost per life year gained and incremental cost per Quality-adjusted life year (QALY).
Outcomes assessed in the review The outcomes assessed in the review were survival rate (mortality) for ACE inhibitor use (to calculate the hazard rate for each treatment group), incidence of angina, estimates of the number of patients who fulfilled AIRE and SAVE type criteria, rates of revascularization, myocardial infarction and hospitalization for heart failure.
Study designs and other criteria for inclusion in the review Previously completed studies and hospital records were included in the review. The inclusion/exclusion criteria were not stated.
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 Approximately 11 studies were used.
Methods of combining primary studies Investigation of differences between primary studies Not stated, even though it would have been applicable.
Results of the review The 4-year mortality rate was 0.3. The calculated hazard rates for placebo and active therapy for AIREwere 222 and 222, and the actual rates were 170 and 169, respectively. The corresponding figures for SAVE were 275 and 275 (calculated), and 228 and 228 (actual), respectively. The incidence of angina on active treatment in both the AIRE and SAVE strategies was 1%. Thirty-five percent of patients with acute myocardial infarction were estimated to fulfil AIRE type criteria and 60% were estimated to fulfil SAVE type criteria. Estimates of the rates of revascularization, myocardial infarction and hospitalization for heart failure were not reported.
Measure of benefits used in the economic analysis Life years gained (LYG) and QALYs gained were the measures of benefit used in the economic analysis. The method of valuation of health states was based on the authors' assumptions in the light of values from the literature. QALYs were derived by multiplying LYG by an arbitrary figure of 0.6.
Direct costs Treatment costs were included in the analysis. Quantities were analysed separately from costs. The discount rate was 6%. The quantity/cost boundary adopted was that of the hospital. The price date was 1994.
Statistical analysis of costs Sensitivity analysis A one-way sensitivity analysis was carried out in order to test the variability in the data. The parameters on which the sensitivity analysis was based were the estimate of long-term survival, the direct incremental cost of treatment, and the incremental costs or savings associated with improved survival in the ACE inhibitor subgroups.
Estimated benefits used in the economic analysis The life years gained with post-MI ACE inhibitor treatment strategies with AIRE type strategy were estimated to be 0.15 and 0.35 for 4 and 10 years, respectively. The corresponding figures with the SAVE strategy were 0.12 and 0.35, respectively. The QALYs with SAVE type strategy were estimated to be 0.12 and 0.35 for 4 and 10 years, respectively.
Cost results The costs of investigations and treatments were estimated to be 2,175 for myocardial infarction, 3,050for chronic heart failure in-patient, 704 for chronic heart failure out-patient, 2,950 for unstable angina and4,799 for stroke.
Synthesis of costs and benefits The estimated benefits and costs were combined as cost per life year and cost per QALY gained. An incremental analysis was therefore performed. Incremental costs per life year gained were calculated for each of the above scenarios. The most optimistic cost per life year gained over 10 years was 1,752 (Strategy A) and 2,962 (Strategy B). Strategy C increased the cost per life year gained of Strategy A to 2,017 and Strategy B to 3,110. The corresponding figures for 4 years were 2,881 and 4,887, 3,408 and 5,241. The incremental cost-effectiveness ratio was found to be very sensitive to drug cost. The results for cost/QALY show that the ratio of the basic risk (AIRE type) scenarios rise to 4,802 per QALY at 4 years and 2,919 per QALY at 10 years. The equivalent ratios for the basic SAVE type scenarios rise to 8,145 and 4,937 respectively.
Authors' conclusions If a low cost ACE inhibitor is used, initial treatment of relatively unselected patients followed by long-term treatment of those at high and medium risk maximises benefit at an acceptable cost. Use of an ACE inhibitor after myocardial infarction is very cost-effective by comparison with many other treatments.
CRD COMMENTARY - Selection of comparators The reason for the choice of comparator is clear. AIRE and SAVE type strategies are two broad approaches of ACE.
Validity of estimate of measure of benefit As noted by the authors, no major effects such as complications of treatment (renal failure) were recorded in the literature used, which is not likely to be the case in 'real life'. This was also the case for compliance with treatment, which may be lower than that used in this study. The validity of estimate of benefit may, therefore need to be treated with some caution.
Validity of estimate of costs Adequate details of the methods of quantity/cost estimation were given except that the potential real life complications were not taken into account in the analysis.
Other issues The authors' conclusions are likely to be justified, although the limitations identified above should not be overlooked. The issue of generalisability to other countries was addressed and appropriate comparisons were made with other studies in terms of lifetime cost per life year gained for the SAVE strategy. The results do not appear to have been presented selectively.
Bibliographic details McMurray J J, McGuire A, Davie A P, Hughes D. Cost-effectiveness of different ACE inhibitor treatment scenarios post-myocardial infarction. European Heart Journal 1997; 18: 1411-1415 Indexing Status Subject indexing assigned by NLM MeSH Angiotensin-Converting Enzyme Inhibitors /economics /therapeutic use; Cost-Benefit Analysis; Humans; Models, Economic; Myocardial Infarction /drug therapy /economics; Quality-Adjusted Life Years; Risk Assessment; Treatment Outcome; Value of Life AccessionNumber 21997008272 Date bibliographic record published 30/04/1999 Date abstract record published 30/04/1999 |
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