|The cost-effectiveness of the treatment of high risk women with osteoporosis, hypertension and hyperlipidaemia in Sweden
|Zethraeus N, Strom O, Borgstrom F, Kanis J A, Jonsson B
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.
The study assessed the cost-effectiveness of treatment of osteoporosis, hypertension, and hyperlipidaemia in different high-risk female populations aged 50 to 80 years. A five-year cholesterol-lowering, antihypertensive, and osteoporosis treatment was cost-effective in nearly all the high-risk female populations from the perspective of Swedish society. The study was based on robust methodology. Although some aspects of the analysis were only partially reported because the economic evaluation was based on a previous model, the authors’ conclusions are likely to be valid.
Type of economic evaluation
The objective was to assess, using a single model, the cost-effectiveness of different treatments for osteoporosis, hypertension and hyperlipidaemia (alone or in combination) in different groups of high-risk female populations aged 50 to 80 years. The risk factors included previous fractures, diabetes and smoking.
The intervention was five-year treatment for osteoporosis, hypertension, and hyperlipidaemia using the following drugs: alendronate (70mg weekly), hydrochlorthiazide (25mg daily), and simvastatin (20mg daily). Each treatment strategy was compared with a no treatment option.
This economic evaluation used a published decision model which was developed to assess the cost-effectiveness of hormone replacement therapy (HRT) for the prevention and treatment of osteoporosis. This model was used to calculate the cost-effectiveness of treatments for osteoporosis, hypertension and hyperlipidaemia which were seen as multifactorial, non-communicable diseases, but with some common possible outcomes (e.g. stroke, coronary heart disease). A lifetime horizon was considered and the authors stated that a societal perspective was adopted.
The clinical data were derived from selected studies which included meta-analyses and randomised clinical trials (RCTs). Baseline risks of events were mostly taken from studies carried out in Sweden. The treatment effect was mainly obtained from RCTs and meta-analyses of RCTs. The key inputs for the decision model were determined in the published model analysis using the available evidence and Swedish epidemiological studies.
Monetary benefit and utility valuations:
The derivation of utility valuations was not described, but it is likely to have been obtained from the previous decision model.
Measure of benefit:
Quality-adjusted life-years (QALYs) were used as the summary benefit measure. QALYs accrued after the first year were discounted at an annual rate of 3%.
The analysis included the costs of the interventions (drugs, consultation, travel, and time) and the direct and indirect costs of the diseases. The analysis also included the costs associated with added years of life. The estimation of costs and resource consumption was based on the previous model which was updated using two more recent studies, the details of which were not given. Some unit costs were reported separately from resource quantities and drug costs were obtained from the Swedish Drug Compendium. The costs were in Swedish kronor (SEK) and were converted to US dollars ($) at the exchange rate of $1 equals SEK 7.5. Future costs were discounted at an annual rate of 3% and the price year was 2005.
Analysis of uncertainty:
A stochastic sensitivity analysis was undertaken using published confidence intervals for the risk reductions of the different therapies. Cost-effectiveness acceptability curves were then generated. In a deterministic sensitivity analysis, the duration of treatment effectiveness was varied between 0 and 10 years, with the effectiveness diminishing linearly during the five years after stopping therapy.
The expected costs and QALYs were not reported.
The cost-effectiveness of interventions versus no interventions varied greatly on the basis of different risk and age-groups.
For osteoporosis treatment in comparison with no treatment, the incremental cost per QALY gained ranged from cost-saving (age 80, T-score -3, previous fractures) to $97,000 (age 50, T-score -2.5, no previous fractures). In general, favourable results were observed in all populations except in 50-year-old women without previous fractures.
For hypertension, treatment was generally cost-effective, with an incremental cost per QALY gained ranging from $25,000 (age 60, with diabetes, a smoker) to $79,000 (age 50, without diabetes, a non-smoker).
For hyperlipidaemia, the incremental cost-utility ratios were even more favourable, ranging from $7,000 (age 50, with diabetes, a smoker) to $52,000 (age 80, without diabetes, a non-smoker).
The treatments of osteoporosis, hypertension, and hyperlipidaemia were cost-effective for most combinations of ages and risk profiles and the exclusion of costs in added years made the cost-utility ratios lower (i.e. more favourable).
The probabilistic sensitivity analysis indicated that treatments were cost-effective at reasonable levels of societal willingness to pay for a QALY.
The authors concluded that a five-year cholesterol-lowering, antihypertensive, and osteoporosis treatment was cost-effective in nearly all the high-risk female populations aged 50 to 80 years from the perspective of Swedish society. The study also demonstrated the feasibility of assessing the cost-effectiveness of interventions in different areas within the context of a single model.
The authors stated that the treatments under examination were the cheapest within one class of first-line drugs. Thus, their selection was justified.
: Relevant sources of data were searched to select recent evidence to supplement the data already included in the previous model. The design of some of these more recent sources was reported and should have ensured the validity of the clinical evidence (RCTs and meta-analyses of RCTs for treatment effect; local data for baseline risk). The authors explained the approach used to calculate risk reductions. The use of QALYs was appropriate not only because they are a validated measure of the impact of the interventions on patients’ health (both quality of life and survival), but also because QALYs allow cross-disease comparisons.
The analysis of costs was carried out from the broadest possible perspective, which included all costs regardless of the payer. As the economic study relied on the previous model, the current analysis provided only information related to the three therapies under examination. The sources of these costs were described in part. Most reflected the Swedish setting, although the provision of more details would have been useful. In general, the methodology of the cost analysis was robust and some characteristics of the study such as the price year, conversion rates, and the use of discounting were appropriately reported.
Analysis and results:
The synthesis of costs and benefits was appropriately performed by means of incremental analysis. However, the study findings were presented selectively given the very large number of risk groups considered. On the one hand, the expected costs and benefits were not reported, but on the other, cost-utility ratios were presented for different patient populations. This enhances the validity of the study. Furthermore, the extensive sensitivity analysis addressed the issue of uncertainty, the key findings being clearly presented. The authors compared their findings with those of published economic evaluations and explained, when appropriate, the reasons for differences in the results.
The study was, in general, based on robust methodology. Some aspects of the analysis were only partially reported because the economic evaluation was based on a previous model. The authors’ conclusions are likely to be valid.
Supported by a grant from the International Osteoporosis Foundation.
Zethraeus N, Strom O, Borgstrom F, Kanis J A, Jonsson B. The cost-effectiveness of the treatment of high risk women with osteoporosis, hypertension and hyperlipidaemia in Sweden. Osteoporosis International 2008; 19(6): 819-827
Other publications of related interest
Zethraeus N, Borgstrom F, Jonsson B, et al. Reassessment of the cost-effectiveness of hormone replacement therapy in Sweden: results based on the Women’s Health Initiative randomised controlled trial. Int J Technol Assess Health Care 2005;21:433–41.
Johannesson M, Jonsson B, Kjekshus J, et al. Cost effectiveness of simvastatin treatment to lower cholesterol levels in patients with coronary heart disease. Scandinavian Simvastatin Survival Study Group. N Engl J Med 1997;336:332–6.
Fleurence RL, Iglesias CP, Torgerson DJ. Economic evaluations of interventions for the prevention and treatment of osteoporosis: a structured review of the literature. Osteoporos Int 2006;17:29–40.
Stevenson M, Lloyd Jones M, De Nigris E, et al. A systematic review and economic evaluation of alendronate, etidronate, risedronate, raloxifene and teriparatide for the prevention and treatment of postmenopausal osteoporosis. Health Technol Assess 2005;9:1–160.
Subject indexing assigned by NLM
Aged; Aged, 80 and over; Alendronate /therapeutic use; Antihypertensive Agents /therapeutic use; Bone Density Conservation Agents /therapeutic use; Cost-Benefit Analysis; Female; Health Care Costs /statistics & Humans; Hydrochlorothiazide /therapeutic use; Hydroxymethylglutaryl-CoA Reductase Inhibitors /therapeutic use; Hyperlipidemias /drug therapy /economics /epidemiology; Hypertension /drug therapy /economics /epidemiology; Middle Aged; Models, Econometric; Osteoporosis, Postmenopausal /drug therapy /economics /epidemiology; Quality-Adjusted Life Years; Simvastatin /therapeutic use; Sweden /epidemiology; numerical data
Date bibliographic record published
Date abstract record published