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Greater first year effectiveness drives favorable cost-effectiveness of brand risedronate versus generic or brand alendronate: modeled Canadian analysis |
Grima D T, Papaioannou A, Thompson M F, Pasquale M K, Adachi J 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. CRD summary This study assessed the cost-effectiveness of risedronate in comparison with generic or brand alendronate, for the treatment of osteoporotic women, aged 65 years or older, with a bone mineral density T-score of -2.5 or less. The authors concluded that risedronate was a cost-effective treatment, when using efficacy data from a large real-world clinical practice. The study was well conducted and used a validated modelling approach. The extensive use of sensitivity analyses makes the authors’ conclusions more robust. Type of economic evaluation Cost-effectiveness analysis, cost-utility analysis Study objective The objective was to assess the cost-effectiveness of risedronate in comparison with generic or brand alendronate for the treatment of osteoporotic women, aged 65 years or older, with a bone mineral density T-score of -2.5 or less, with or without previous fractures. Interventions The two interventions were one year of treatment with either risedronate (35mg once a week) or alendronate (70mg once a week). Methods Analytical approach:This economic evaluation used a published decision model which was populated with Canadian data. The time horizon of the study was five years. The authors stated that the perspective of the Canadian public payer (the provincial Ministry of Health) was adopted.
Effectiveness data:The clinical data were derived from a selection of known, relevant studies which were identified by the authors. The bulk of evidence on the treatment efficacy came from the RisedronatE and ALendronate (REAL) retrospective cohort study which enrolled over 35,000 women receiving brand risedronate or brand alendronate once a week. The length of follow-up for these women appears to have been one year. Other epidemiological data came from national sources such as the Canadian Multicentre Osteoporosis Study database or Canadian life tables. Well-known published studies, performed in other countries, were used only when Canadian data were not available.
Monetary benefit and utility valuations:The utility values were derived from published sources, but the details of these were not given.
Measure of benefit:Quality-adjusted life-years (QALYs) and hip fractures were the summary benefit measures derived from the decision model. A 5% annual discount rate was applied to the QALYs.
Cost data:The economic analysis included the costs of physician visits, tests and procedures, emergency room visits, hospitalisations (ward stay, procedures, assessments, and medications), long-term care, home care, and study medications. All medical costs referred to hip fractures. The costs of drugs came from the Ontario Drug Benefit Formulary and did not include dispensing fees or mark-ups. The unit costs for brand risedronate and generic alendronate were used in the base case. The first year of costs for hip fractures were derived from a published study, after excluding the cost of long-term care, informal care, and patient co-payments. The cost of hip fracture after the first year was based on some authors’ assumptions and published evidence and was mainly the costs of long-term care. All costs were discounted at an annual rate of 5%. They were in Canadian dollars (CAD) and the price year was 2006.
Analysis of uncertainty:A probabilistic sensitivity analysis based on a second-order Monte Carlo simulation was carried out, using published confidence intervals, to deal with the issue of uncertainty around the estimated relative risk of fracture. A deterministic sensitivity analysis was also undertaken on the key model inputs considering alternative estimates or scenarios. Results In a hypothetical cohort of 1,000 patients, the expected costs were CAD 2,931,773 with generic alendronate and CAD 2,945,078 with risedronate, while the expected total hip fractures were 92.91 with alendronate and 85.78 with risedronate and the expected QALYs were 3,521.94 with alendronate and 3,525.37 with risedronate.
The incremental cost per hip fracture avoided with risedronate over generic alendronate was CAD 1,867, while the incremental cost per QALY was CAD 3,877.
The probabilistic sensitivity analysis indicated that in 94% of the simulations the incremental cost (for risedronate over alendronate) per hip fracture avoided was below the threshold of CAD 20,000 and in 68% of simulations the incremental cost per QALY gained was below this threshold.
The deterministic sensitivity analysis showed that the cost-effectiveness of risedronate ranged from dominant (less expensive and more effective than alendronate) with a longer time-horizon or a higher cost of hip fractures, to an incremental cost per QALY gained of CAD 14,985 under the less favourable conditions. Authors' conclusions The authors concluded that risedronate was a cost-effective treatment for osteoporosis compared with generic or brand alendronate, in postmenopausal Canadian women, when using efficacy data from a large real-world clinical practice. CRD commentary Interventions:The authors justified their selection of the comparators. Risedronate and alendronate were the most commonly prescribed oral bisphosphonates in Canada.
Effectiveness/benefits:The authors justified their selection of the REAL study as the main source for evidence. It was noted that large cohort studies provide reliable data on the efficacy of treatment, as suggested in the Canadian guidelines for cost-effectiveness studies. The authors used an appropriate regression model to adjust for any potential differences in the two treatment groups. Other sources of data were appropriately selected to reflect the country-specific epidemiological setting. Little information on the derivation of the utility data used to calculate the QALYs was provided, which prevents an objective assessment of the validity of these estimates. However, all uncertain inputs were tested in the sensitivity analysis. Both a disease-specific and a more generalisable benefit measure were used, which are appropriate for making relevant comparisons with the results from other studies.
Costs:The analysis of costs was consistent with the perspective. The costs were presented as macro-categories and a breakdown of cost items was not provided. The data on resource use and unit costs were not reported. This limits the transparency of the economic analysis. Furthermore, fracture costs were derived from a published study, the methodology of which was not described. Other details of the study, such as the price year and use of discounting were reported. In general, the cost estimates were treated deterministically, but variation in costs was considered in the sensitivity analysis.
Analysis and results:The synthesis of the costs and benefits was appropriately carried out using an incremental approach. The findings were clearly presented. The issue of uncertainty was appropriately addressed in the sensitivity analysis which used both a deterministic and a probabilistic approach. The results of the alternative scenarios were clearly presented and discussed. The authors noted that country-specific data were used, which limits the external validity and the generalisability of the findings to other settings. The authors noted some limitations of their analysis, mainly related to the need for assumptions and data extrapolation beyond the study follow-up period.
Concluding remarks:Overall, the study was well conducted and used a validated modelling approach. The extensive use of sensitivity analyses makes the authors’ conclusions more robust. Funding Funding provided by the Alliance for Better Bone Health. Bibliographic details Grima D T, Papaioannou A, Thompson M F, Pasquale M K, Adachi J D. Greater first year effectiveness drives favorable cost-effectiveness of brand risedronate versus generic or brand alendronate: modeled Canadian analysis. Osteoporosis International 2008; 19(5): 687-697 Other publications of related interest Borgstrom F, Carlsson A, Sintonen H, et al. The cost-effectiveness of risedronate in the treatment of osteoporosis: an international perspective. Osteoporos Int 2006;17:996-1007.
Zethraeus N, Borgstrom F, Strom O, et al. Cost-effectiveness of the treatment and prevention of osteoporosis-a review of the literature and a reference model. Osteoporos Int 2007;18:9-23.
Silverman SL, Watts NB, Delmas PD, et al. Effectiveness of bisphosphonates on nonvertebral and hip fractures in the first year of therapy: the risedronate and alendronate (REAL) cohort study. Osteoporos Int 2007;18:25-34.
Tosteson AN, Jönsson B, Grima DT, et al. Challenges for model-based economic evaluations of post-menopausal osteoporosis interventions. Osteoporos Int 2001;12:849-57.
Kanis JA, Borgstrom F, Johnell O, et al. Cost-effectiveness of risedronate for the treatment of osteoporosis and prevention of fractures in postmenopausal women. Osteoporos Int 2004;15:862-71. Indexing Status Subject indexing assigned by NLM MeSH Aged; Aged, 80 and over; Alendronate /economics /therapeutic use; Bone Density /drug effects; Bone Density Conservation Agents /economics /therapeutic use; Canada; Cost-Benefit Analysis; Etidronic Acid /analogs & Female; Hip Fractures /drug therapy /economics; Humans; Models, Biological; Osteoporosis, Postmenopausal /drug therapy /economics; Quality-Adjusted Life Years; Risedronate Sodium; Severity of Illness Index; derivatives /economics /therapeutic use AccessionNumber 22008100785 Date bibliographic record published 03/02/2009 Date abstract record published 13/05/2009 |
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