|An economic evaluation of quantitative ultrasonometry as pre-screening test for the identification of patients with osteoporosis
|Hiligsmann M, Ethgen O, Bruyere O, Reginster JY
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 objective was to assess the cost-effectiveness of pre-screening for osteoporosis using several quantitative ultrasound index thresholds to identify those at risk. The authors concluded that quantitative ultrasound could be useful as a pre-screening tool and index thresholds of -1.0 and -1.5 were the most appropriate. The methodology was adequate and, with the exception of details of the literature review, the methods and results were well reported. The authors’ conclusions appear to be appropriate, given the scope of the analysis.
Type of economic evaluation
Cost-effectiveness analysis, cost-utility analysis
The objective was to assess the cost-effectiveness of pre-screening for osteoporosis, using several quantitative ultrasound (QUS) index thresholds to identify those at high risk.
The three screening strategies for osteoporosis were dual-energy X-ray absoptiometry (DXA) testing; QUS pre-screening with DXA testing for those at high risk, defined by several QUS index thresholds, which were -2.5, -2.0, -1.5, -1.0, -0.5, and 0.0; and no screening. Three age groups were analysed; 50 to 59 years, 60 to 69 years, and 70 to 79 years.
Belgium/out-patient secondary care.
A decision tree model, with a cohort of 1,000 women, was used for the cost-effectiveness analysis. This model was then combined with a validated Markov micro-simulation model to estimate the lifetime costs and outcomes (Hiligsmann, et al. 2009, see 'Other Publications of Related Interest' below for bibliographic details). A lifetime horizon was used and the authors reported that the perspective was that of the Belgian health care system.
The effectiveness and clinical data were derived from published studies. The main clinical effectiveness estimate was the sensitivity and specificity of QUS at different index thresholds. These estimates were obtained from a recent meta-analysis.
Monetary benefit and utility valuations:
The utilities for the general population and the relative reductions due to fractures were derived from a published systematic review (Hiligsmann, et al. 2008, see 'Other Publications of Related Interest' below for bibliographic details).
Measure of benefit:
The number of DXA scans required per patient detected and quality-adjusted life-years (QALYs) gained were the measures of benefit. As QALYs could be generated over the lifetime of the patient, these were discounted at an annual rate of 1.5%.
The direct costs were those relating to QUS and DXA screening; physician visits; medications, including alendronate, calcium and vitamin D; bone densitometry measurements; and the health care costs of treating bone fractures, including hospitalisation and long-term institutionalisation. All these direct costs were derived from published studies. The indirect costs were also included and these were estimated by multiplying the proportion of productivity lost due to fractures by the workforce participation rates and by the average annual wage for employed women. The price year was 2006 and, as the costs could be incurred over the lifetime of the patient, future costs were discounted at an annual rate of 3%. All costs were reported in Euros (EUR).
Analysis of uncertainty:
A series of univariate analyses were performed to test the stability of the results. The following model parameters were varied: screening costs, discount rate, fracture risk, fracture disutility, fracture cost, treatment cost, treatment efficacy, and medication non-adherence.
The strategies using QUS thresholds of -2.5, -2.0, -0.5, and 0.0 were extendedly dominated for all age groups, because their incremental cost-effectiveness ratios were greater than the next more effective alternative. The remaining strategies were no screening, pre-screening using QUS thresholds of -1.0 and -1.5, and DXA screening alone, except in women aged 70 to 79 years, where pre-screening using a QUS threshold of -1.0 was also dominated.
For all age groups, DXA screening alone generated the highest average costs, ranging for different age groups from EUR 4,993 to EUR 7,424, and the highest number of QALYs, which ranged from 8.0622 to 18.2772. No screening generated the lowest average costs (EUR 4,889 to EUR 7,318) and the lowest number of QALYs (8.0565 to 18.2759).
In the cost-utility analysis, the strategies using QUS thresholds of -2.5, -2.0, -0.5, and 0.0 were extendedly dominated for all age groups. Compared with no screening, pre-screening using a QUS threshold of -1.5 had an incremental cost per QALY gained of EUR 75,073 for 55-year-old women, EUR 33,466 for 65-year-old women, and EUR 17,831 for 75-year-old women. Compared with pre-screening using a threshold of -1.5, using a threshold of -1.0 generated an incremental cost per QALY gained of EUR 92,010 for 55-year-old women, EUR 38,085 for 65-year-old women, and was extendedly dominated in 75-year-old women. Compared with pre-screening using a threshold of -1.0, DXA screening generated an additional cost per QALY gained of EUR 106,938 for 55-year-old women, EUR 41,181 for 65-year-old women, and EUR 19,707 for 75-year-old women.
The univariate sensitivity analysis found that changes in the screening costs had the most impact on the results. A 20% reduction in DXA costs resulted in nearly all the other interventions being dominated and all pre-screening QUS strategies were dominated at a DXA cost of EUR 27.
The authors concluded that QUS could be useful as a pre-screening tool and index thresholds of -1.0 and -1.5 were the most appropriate.
The interventions were reported clearly and in detail.
The effectiveness and clinical data were derived from published studies. The authors did not report how these studies were sought nor the criteria used to select them. As a result, it is not possible to determine if all the relevant information was included. The main effectiveness and clinical parameters, the values used in the model, and their sources were reported. The methods used to obtain the utility measures for the QALYs were adequately reported.
The authors reported that a Belgian health care system perspective was adopted, but productivity costs were included and the perspective should, therefore, have been societal. They adequately reported how the cost information was obtained, the price year, time horizon, discount rate used, and currency information.
Analysis and results:
A decision tree and a Markov model were used to combine the costs and outcomes. Adequate details of the models and diagrams were reported. The Markov model had already been validated and the authors provided the references for this. The impact of uncertainty on the model’s results was considered using one-way sensitivity analyses, but probabilistic sensitivity analyses would have more thoroughly captured the overall model uncertainty. The authors adequately reported the limitations of their analysis.
The methodology was adequate and, with the exception of the details of the literature review, the methods and results were well reported. The authors’ conclusions appear to be appropriate, given the scope of the analysis.
Hiligsmann M, Ethgen O, Bruyere O, Reginster JY. An economic evaluation of quantitative ultrasonometry as pre-screening test for the identification of patients with osteoporosis. Disease Management and Health Outcomes 2008; 16(6): 429-438
Other publications of related interest
Hiligsmann M, Ethgen O, Bruyere O, et al. Development and validation of a Markov microsimulation model for the economic evaluation of treatments in osteoporosis. Value in Health. 2009; 12(5): 687-696.
Hiligsmann M, Ethgen O, Richy F, et al. Utility values associated with osteoporotic fracture: a systematic review of the literature. Calcified Tissue International 2008; 82: 288-292.
Subject indexing assigned by CRD
Absorptiometry, Photon; Bone Density; Cost-Benefit Analysis; Humans; Markov Chains; Mass Screening; Osteoporosis; Quality-Adjusted Life Years; Ultrasonography
Date bibliographic record published
Date abstract record published