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Cost effectiveness of leukotriene receptor antagonists versus long-acting beta-2 agonists as add-on therapy to inhaled corticosteroids for asthma: a pragmatic trial |
Wilson EC, Price D, Musgrave SD, Sims EJ, Shepstone L, Murdoch J, Mugford HM, Blyth A, Juniper EF, Ayres JG, Wolfe S, Freeman D, Gilbert RF, Hillyer EV, Harvey I |
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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 aim was to estimate the costs and health effects of additional therapy for the management of patients with chronic asthma, the symptoms of which were not controlled on low-dose inhaled corticosteroids. The authors concluded that leukotriene receptor antagonists were marginally cost-effective compared with long-acting beta-2 adrenergic receptor agonists, but there was significant uncertainty. The methods were satisfactory and they and the results were sufficiently reported. The authors’ conclusions appear to be appropriate. Type of economic evaluation Cost-effectiveness analysis, cost-utility analysis Study objective The aim was to estimate the costs and health effects of add-on therapies in the management of patients with chronic asthma, the symptoms of which were not controlled with low-dose inhaled corticosteroids. Interventions Leukotriene receptor antagonist (LTRA) therapy was compared with the usual add-on therapy of a long-acting beta-2 adrenergic receptor agonist (β2 agonist). The LTRA was either montelukast 10mg once daily or zafirlukast 20mg twice daily, while the β2 agonist was salmeterol, formoterol, or a fixed-dose combination with an inhaled corticosteroid, which were fluticasone-salmeterol or budesonide-formoterol. Methods Analytical approach:An economic evaluation was undertaken alongside a randomised controlled clinical trial, in 53 primary care practices. The time horizon was two years and the authors’ stated that the perspectives were those of the UK National Health Service (NHS) and society.
Effectiveness data:The effectiveness data were from a multicentre, single-blind, prospective, randomised controlled trial (Price, et al. 2011, see ‘Other Publications of Related Interest’ below for bibliographic details). The primary outcome was the improvement in asthma-specific quality of life measured by the Mini Asthma Quality of Life Questionnaire (AQLQ) and the Asthma Control Questionnaire (ACQ).
Monetary benefit and utility valuations:The utility scores were measured using the European Quality of life (EQ-5D) questionnaire. They were converted into the measure of benefit, using standard UK population conversion algorithms. Measurements were taken during the trial at two, six, 12, 18, and 24 months of follow-up.
Measure of benefit:The measures of benefit were quality-adjusted life-years (QALYs) and the improvements in Mini AQLQ and ACQ; these were discounted at a rate of 3.5% per annum.
Cost data:The cost categories were prescribed medications and devices, over-the-counter (OTC) medications, primary and secondary care, and lost productivity. These were reported for resource use due to asthma, lower respiratory tract infections, and other relevant allergic conditions. The resource estimates were from general practitioner databases and patient-completed diaries. The unit costs for prescription medicines were from the British National Formulary, and for OTC medicines they were from patient estimates or pharmacy websites. NHS Reference costs were used for NHS care and patient-reported hours off work were used to estimate the lost productivity costs, by multiplying the hours by the 2005 national average gross hourly wage. All costs were reported in 2005 UK pounds sterling (£) and discounted at 3.5% per annum.
Analysis of uncertainty:A non-parametric bootstrapping approach was used to generate 95% confidence intervals and cost-effectiveness acceptability curves. Results The asthma-specific quality of life scores were similar between the two interventions and the differences were not statistically significant. Over two years, from a NHS perspective, the discounted mean QALYs were 1.601 for LTRA treatment and 1.548 for long-acting β2 agonists. From a societal perspective, they were 1.610 for LTRA treatment and 1.566 for long-acting β2 agonists.
There were no statistically significant cost differences at either two months or two years. From a NHS perspective, the discounted mean costs, over two years, were £956 for LTRA treatment and £869 for long-acting β2 agonists. From a societal perspective, they were £1,157 for LTRAs and £952 for long-acting β2 agonists.
From a NHS perspective, the incremental cost per QALY gained for LTRA over long-acting β2 agonists was £11,919 and, from a societal perspective, it was £22,589.
At a willingness-to-pay threshold of £30,000 per QALY, there was a 53.16% probability that LTRAs were cost-effective, from an NHS perspective, and a 51.56% probability, from a societal perspective. Authors' conclusions The authors concluded that LTRA therapy was marginally cost-effective, compared with long-acting β2 agonists, for patients with chronic asthma, but there was significant uncertainty. CRD commentary Interventions:The interventions were described and long-acting β2 agonists were the usual clinical practice in the UK. The interventions appear to have been appropriate comparators and the population was reported.
Effectiveness/benefits:The effectiveness data were from a rigorous multicentre randomised controlled trial, which appears to have produced estimates of high quality. It is unclear if a systematic review was performed to identify the relevant data, which means that it is unclear if all the best available evidence was used. The measure of benefit was described and appropriate discounting was performed.
Costs:The costing methods, types of resources included, price sources, and the results were clearly stated. The costs appear to have been relevant to each perspective and productivity losses were appropriately included for the societal perspective. The costs were discounted at a recommended rate and adjusted for inflation.
Analysis and results:The details of the model structure were reported, and it appears to have appropriately synthesised the information. The results were reported separately and combined into incremental cost-effectiveness ratios, making them generalisable to other settings. The authors discussed the limitations of their study and a patient-level bootstrapping analysis tested the uncertainty in the individual results.
Concluding remarks:The methods were satisfactory and the results were reported with sufficient detail. The authors’ conclusions appear to be appropriate. Funding Funded by the NIHR Health Technology Assessment programme. Support also received from Clement-Clarke International, Merck Sharpe and Dohme Ltd, AstraZeneca Ltd, and Respiratory Research Ltd. Bibliographic details Wilson EC, Price D, Musgrave SD, Sims EJ, Shepstone L, Murdoch J, Mugford HM, Blyth A, Juniper EF, Ayres JG, Wolfe S, Freeman D, Gilbert RF, Hillyer EV, Harvey I. Cost effectiveness of leukotriene receptor antagonists versus long-acting beta-2 agonists as add-on therapy to inhaled corticosteroids for asthma: a pragmatic trial. PharmacoEconomics 2010; 28(7): 597-608 Other publications of related interest Price D, Musgrave SD, Wilson E, et al. A pragmatic single-blind RCT and health economic evaluation of leukotriene receptor antagonists in primary care at steps two and three of the national asthma guidelines (ELEVATE). Health Technology Assessment 2011; In press. Indexing Status Subject indexing assigned by NLM MeSH Administration, Inhalation; Adolescent; Adrenal Cortex Hormones /administration & Adrenergic beta-2 Receptor Agonists; Adrenergic beta-Agonists /administration & Adult; Aged; Aged, 80 and over; Asthma /drug therapy; Child; Cost-Benefit Analysis; Delayed-Action Preparations; Drug Therapy, Combination; Great Britain; Humans; Leukotriene Antagonists /administration & Middle Aged; Quality-Adjusted Life Years; Surveys and Questionnaires; Treatment Outcome; Young Adult; dosage /economics /therapeutic use; dosage /economics /therapeutic use; dosage /economics /therapeutic use AccessionNumber 22010001236 Date bibliographic record published 10/11/2010 Date abstract record published 02/02/2011 |
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