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The lifetime cost effectiveness of amlodipine-based therapy plus atorvastatin compared with atenolol plus atorvastatin, amlodipine-based therapy alone and atenolol-based therapy alone: results from ASCOT |
Lindgren P, Buxton M, Kahan T, Poulter NR, Dahlof B, Sever PS, Wedel H, Jonsson B, Anglo-Scandinavian Cardiac Outcomes Trial investigators |
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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 This study evaluated the cost-effectiveness of four strategies for the treatment of patients who had hypertension and three or more cardiovascular risk factors, in the UK and Sweden. These were amlodipine- or atenolol-based therapy, with or without atorvastatin. The authors concluded that amlodipine-based therapy with atorvastatin appeared to be cost-effective. The methods seem to have been appropriate and were clearly and transparently reported. The conclusions reached by the authors appear to be valid. Type of economic evaluation Cost-effectiveness analysis, cost-utility analysis Study objective The aim was to evaluate the cost-effectiveness of four strategies for the treatment of patients who had hypertension and three or more cardiovascular risk factors, in the UK and Sweden. Interventions The four strategies were amlodipine-based with atorvastatin, atenolol-based with atorvastatin, amlodipine-based only, and atenolol-based only. The amlodipine-based regimen was supplemented with perindopril if needed to reach the blood pressure targets and the atenolol-based regimen was supplemented with bendroflumethiazide and potassium if needed. Placebo was given in the two strategies without atorvastatin. Location/setting UK and Sweden/out-patient and in-patient care. Methods Analytical approach:A Markov model, with a lifetime horizon, was used to capture the ongoing risk of cardiovascular-related clinical events. The data were derived from a single clinical study. The authors reported that a UK National Health Service (NHS) perspective was used for the UK, and a societal perspective was used for Sweden.
Effectiveness data:The evidence came from patient-level data from the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT). This was a randomised multi-centre two-by-two factorial trial that evaluated 19,257 patients. The blood-pressure lowering arm was stopped prematurely after a median follow-up of 5.5 years. The results for Sweden and the UK were used. The primary endpoint was the combined outcome of non-fatal myocardial infarction and fatal coronary heart disease.
Monetary benefit and utility valuations:Event-free patients were assumed to have the utilities of the general Swedish or UK populations and these were from published studies that used the European Quality of life (EQ-5D) questionnaire. To evaluate the utilities for events, data from a subsample of Swedish patients from the ASCOT were used for myocardial infarction and stroke, and an assumption based on another Swedish study was used for revascularisations.
Measure of benefit:The measures of benefit were life-years gained and quality-adjusted life-years (QALYs). Future benefits were discounted annually at 3.5% in the UK and at 3.0% in Sweden.
Cost data:The cost categories were in-patient and out-patient care and drugs. The resource use was based on the ASCOT data. For the Swedish societal perspective, the indirect costs for the first year were based on a Swedish subsample of the trial. The costs were inflated to the 2007 price year, using the consumer price index, and expressed in Euros (EUR). The conversion rates were EUR 1 was equal to 9.08 Swedish Kronor or 0.66 UK pounds sterling. The unit costs were from local sources, except for the cost of perindopril, which was not available in Sweden and was assumed to be the same as in the UK.
Analysis of uncertainty:One-way sensitivity analysis was performed to assess the impact of variations in the key model inputs. Probabilistic sensitivity analysis was also performed, using the underlying parameter distributions from the trial data, and the results were presented in cost-effectiveness acceptability curves. Results In the base case, the QALYs for Sweden were 9.94 for atenolol-based therapy with placebo; 9.96 for amlodipine-based therapy with placebo; 9.98 for atenolol-based therapy with atorvastatin; and 10.03 for amlodipine-based therapy with atorvastatin. In the UK, the QALYs were 8.94 for atenolol-based therapy; 8.96 for amlodipine-based therapy; 8.98 for atenolol-based therapy with atorvastatin; and 9.02 for amlodipine-based therapy with atorvastatin.
The total costs in Sweden were EUR 4,778 for atenolol-based therapy; EUR 4,878 for amlodipine-based therapy; EUR 5,444 for atenolol-based therapy with atorvastatin; and EUR 5,493 for amlodipine-based therapy with atorvastatin. In the UK, the costs were EUR 3,221 for atenolol-based therapy; EUR 3,417 for amlodipine-based therapy; EUR 3,989 for atenolol-based therapy with atorvastatin; and EUR 4,169 for amlodipine-based therapy with atorvastatin.
Atenolol-based therapy with atorvastatin was extendedly dominated, which means that it was less effective than another regimen that had a lower cost per QALY. In Sweden, the incremental cost per QALY, for non-dominated strategies, was EUR 3,965 for amlodipine-based only over atenolol-based only, and EUR 8,591 for amlodipine-based with atorvastatin over amlodipine-based without. In the UK it was EUR 9,548 for amlodipine-based over atenolol-based and EUR 11,965 for amlodipine-based with atorvastatin over without. If the willingness-to-pay was over EUR 12,000, amlodipine-based therapy with atorvastatin was the best strategy, in either country.
These results were robust to the variations tested. Authors' conclusions The authors concluded that, in the UK and Sweden, the combination of amlodipine-based therapy and atorvastatin appeared to be cost-effective. CRD commentary Interventions:The interventions were described and the reference for the clinical trial was given. The trial appears to have been relevant for the health problem and these comparators might be relevant in other settings.
Effectiveness/benefits:The clinical data were from a large, well-conducted randomised controlled trial, in a relevant setting, and this should ensure a high quality for these data. The benefits were estimated using patient-level data from the ASCOT. The details were adequately reported, except for the utility estimation, where the authors referred the reader to other studies.
Costs:It appears that the cost categories were relevant to the selected perspective, for each country. The costs of the events were from the clinical trial and these might have been different to the real costs, as they excluded some items, such as the rehabilitation of stroke. The authors stated that the Swedish indirect costs were a conservative assumption, as they were only included for the first year. The methods used to adjust the cost data were well reported.
Analysis and results:An incremental cost-effectiveness analysis was performed and the authors appropriately reported the study and analysed the data. The uncertainty was generally sufficiently evaluated.
Concluding remarks:On the whole, the methods seem to have been appropriate and were clearly and transparently reported. The conclusions reached by the authors appear to be valid. Funding Supported by Pfizer Inc, New York, USA. Bibliographic details Lindgren P, Buxton M, Kahan T, Poulter NR, Dahlof B, Sever PS, Wedel H, Jonsson B, Anglo-Scandinavian Cardiac Outcomes Trial investigators. The lifetime cost effectiveness of amlodipine-based therapy plus atorvastatin compared with atenolol plus atorvastatin, amlodipine-based therapy alone and atenolol-based therapy alone: results from ASCOT. PharmacoEconomics 2009; 27(3): 221-230 Indexing Status Subject indexing assigned by NLM MeSH Adrenergic beta-Antagonists /economics /therapeutic use; Amlodipine /economics /therapeutic use; Antihypertensive Agents /economics /therapeutic use; Atenolol /economics /therapeutic use; Atorvastatin Calcium; Calcium Channel Blockers /economics /therapeutic use; Cardiovascular Diseases /economics /prevention & Cost-Benefit Analysis; Drug Therapy, Combination; Heptanoic Acids /economics /therapeutic use; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors /economics /therapeutic use; Hypertension /drug therapy /economics; Models, Economic; Pyrroles /economics /therapeutic use; Scandinavian and Nordic Countries; Treatment Outcome; control AccessionNumber 22009101471 Date bibliographic record published 27/01/2010 Date abstract record published 06/10/2010 |
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