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Economic analysis of the use of coronary calcium scoring as an alternative to stress ECG in the non-invasive diagnosis of coronary artery disease |
Raman V, McWilliams ET, Holmberg SR, Miles K |
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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. CRD summary The study estimated the cost-effectiveness of coronary calcium scoring compared with stress electrocardiogram (ECG) testing for diagnosis of coronary artery disease. The authors concluded that coronary calcium scoring as an initial diagnostic test was cost-effective if the prior probability of coronary artery disease was below 30%. Most of the study methods used seemed adequate but some were not reported in detail, particularly the costs and utilities. This makes it difficult to fully assess the authors' conclusions. Type of economic evaluation Cost-effectiveness analysis, cost-utility analysis Study objective The objective was to estimate the cost-effectiveness of coronary calcium scoring testing as an alternative to stress ECG testing for non-invasive diagnosis of coronary artery disease in patients with symptoms suspicious of stable angina. Interventions Six strategies (tests) were compared. Four tests were previously assessed management pathways: coronary angiography alone; stress ECG before coronary angiography; myocardial perfusion scintigraphy before coronary angiography; and stress ECG before myocardial perfusion scintigraphy and coronary angiography. The two new tests assessed were coronary calcium scoring before coronary angiography, and coronary calcium scoring before myocardial perfusion scintigraphy plus coronary angiography. Methods Analytical approach:A decision-tree model was used to combine data that reported the diagnostic accuracy of the different tests from the published literature. The authors stated the study perspective was that of the healthcare purchaser. Effectiveness data:Clinical effectiveness estimates for the sensitivity and specificity of the tests came from an update of a published systematic literature review with meta-analysis (O’ Rourke, et al, 2000, see 'Other Publications of Related Interest' below for bibliographic details) conducted by the authors to include more recent studies (published from 2000 up to 2008). The primary clinical outcomes were the proportion of patients correctly diagnosed and correctly defined health states (true positive, false negative, true negative, death). Monetary benefit and utility valuations:The utility values were based on previous National Institute for Health and Clinical Excellence (NICE) appraisals (NICE, 2003 and Mowatt, et al, 2004, see 'Other Publications of Related Interest' below for bibliographic details). Measure of benefit:Quality-adjusted life-years (QALYs) and the net monetary benefit were the summary benefit measures. Cost data:The costs included were the prices of different diagnostic tests and the average treatment costs for each health state following diagnosis. The cost data were taken from a previous published economic analysis conducted for the NICE (NICE, 2003 and Mowatt, 2004) and national tariffs from the UK Department of Health, which reflected the average prices for hospital procedures in 2004. All costs were reported in UK £. Analysis of uncertainty:One-way sensitivity analysis was conducted on the estimates of baseline prevalence of coronary artery disease, and the sensitivity and specificity of diagnostic tests. The results were presented using cost-effectiveness acceptability curves using the derived net monetary benefit. Results At the baseline prevalence of coronary artery disease of 10.5%, the QALY estimates ranged from 12.472 for the stress ECG before myocardial perfusion scintigraphy to 12.509 for coronary calcium scoring. At higher prevalence of coronary artery disease, these tests also gave the highest and lowest QALY estimates. At the baseline prevalence of coronary artery disease of 10.5%, the total cost of diagnosis ranged from £6,239 with stress ECG before myocardial perfusion scintigraphy to £7,114 for coronary calcium scoring. At higher disease prevalence, the same tests were still the most and least costly. Compared with myocardial perfusion scintigraphy (at the baseline prevalence of coronary artery disease of 10.5%), the most cost-effective option was coronary calcium scoring, with a net monetary benefit of £759.40. Coronary calcium scoring remained the most cost-effective strategy at higher disease prevalence levels compared with stress ECG before myocardial perfusion scintigraphy, unless disease prevalence was higher than 30%; at a disease prevalence of 50%, coronary angiography was the most cost-effective test. Authors' conclusions The authors concluded that use of coronary calcium scoring as an initial method for investigating patients with suspected stable angina was cost-effective if the prior probability of coronary artery disease was less than 30%. In patients with a prior probability of coronary artery disease higher than 30%, it would be more cost-effective to proceed to myocardial perfusion scintigraphy or coronary angiography alone than to use either coronary calcium scoring or stress ECG tests. CRD commentary Interventions:The rationale for the selection of the comparators appeared to be relevant as they were based on guidelines produced for the study setting (UK). The tests evaluated were not described in depth. Effectiveness/benefits:The effectiveness data came from an update of an existing systematic review with meta-analysis; the authors reported the methods used in this updated systematic review. The time horizon of the analysis was not stated explicitly; it appeared to cover the initial diagnostic period, subsequent treatment period, and the quality adjusted survival over the longer term. The estimates of average QALYs and average treatment costs were related according to diagnosis. The authors did not report details supporting the calculation of QALYs, so the quality of these estimates could not be assessed. Costs:The included costs appeared to be relevant to the perspective stated by the authors. The sources of resource use and prices were provided with references but were reported as total costs, so it was difficult to assess whether all relevant costs were included or whether they were applicable to other settings. A number of cost assumptions came from previous NICE assessments (NICE, 2003 and Mowatt, 2004), but full details were not reported in the study. The time horizon of the analysis was not stated, so it was difficult to assess whether discounting of costs should have been included. No other adjustments of costs were reported. Analysis and results:All the selected evidence on costs and outcomes was combined in a decision-tree model. Details of the model were given including a diagram. The use of an incremental analysis was appropriate to assess the relative cost-effectiveness of the different strategies. The level of reporting of the results was adequate. Uncertainty was addressed to an extent using a one-way sensitivity analysis, but a probabilistic sensitivity analysis could have captured the overall parameter uncertainty more thoroughly. The authors acknowledged some limitations of their analysis. The generalisability of the results to other settings was discussed. Concluding remarks:Most of the methods used seemed adequate but some were not reported in detail, particularly the costs and utilities. This makes it difficult to fully assess the authors' conclusions. Bibliographic details Raman V, McWilliams ET, Holmberg SR, Miles K. Economic analysis of the use of coronary calcium scoring as an alternative to stress ECG in the non-invasive diagnosis of coronary artery disease. European Radiology 2012; 22(3): 579-587 Other publications of related interest O'Rourke RA, Brundage BH, Froelicher VF, Greenland P, Grundy SM, Hachamovitch R, Pohost GM, Shaw LJ, Weintraub WS, Winters WL, Forrester JS, Douglas PS, Faxon DP, Fisher JD, Gregoratos G, Hochman JS, Hutter AM Jr, Kaul S, Wolk MJ. American College of Cardiology/American Heart Association Expert Consensus document on electron-beam computed tomography for the diagnosis and prognosis of coronary heart disease. Circulation 2000;102(1):126-140. National Institute for Health and Clinical Excellence (2003) Myocardial perfusion scintigraphy for the diagnosis and management of angina and myocardial infarction. London. National Institute for Health and Clinical Excellence. Technology Appraisal; 73. 2003 Mowatt G, Vale L, Brazzelli M, Hernandez R, Murray A, Scott N, Fraser C, McKenzie L, Gemmell H, Hillis G, Metcalfe M. Systematic review of the effectiveness and cost-effectiveness, and economic evaluation, of myocardial perfusion scintigraphy for the diagnosis and management of angina and myocardial infarction. Health Technology Assessment 2004;8(30):1-222. Indexing Status Subject indexing assigned by NLM MeSH Calcinosis /radiography; Coronary Angiography /economics; Coronary Disease /radiography; Cost-Benefit Analysis; Decision Trees; Electrocardiography /economics; Exercise Test /economics; Great Britain; Humans; Predictive Value of Tests; Quality-Adjusted Life Years; Sensitivity and Specificity; Tomography, X-Ray Computed /economics AccessionNumber 22012007366 Date bibliographic record published 19/04/2012 Date abstract record published 10/07/2012 |
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