Abstract
Background: Screening for osteoporosis has been recommended to identify patients at high risk of fracture in order to provide preventative treatment. Given the limited availability of dual-energy x-ray absorptiometry (DXA) and health resources, quantitative ultrasonometry (QUS) has emerged as an attractive tool for the mass screening scenario. The objective of this study was to evaluate whether a screening strategy using QUS as a pre-screening tool for bone densitometry would be cost effective and, if so, at what cut-off thresholds.
Methods: Decision analytic models were used to compare the cost effectiveness and cost utility of several screening strategies: DXA measurement alone and pre-screening strategies that use different QUS index cut-off thresholds. For each strategy, and for hypothetical cohorts of women, we estimated the number of DXA scans required, the number of osteoporotic patients detected and missed, the total screening cost, and the incremental cost per patient detected. A validated Markov microsimulation model with a lifetime horizon and from a healthcare perspective was also computed in order to estimate the cost per quality-adjusted life-year (QALY) gained of the alternative screening strategies combined with 5 years of alendronate therapy for women who have osteoporosis (T-score -2.5 or less).
Results: The DXA strategy had the highest cost and the highest number of patients with osteoporosis detected. Pre-screening strategies using QUS reduced the number of DXA scans per patient with osteoporosis detected and the total screening cost but they also missed patients with osteoporosis as the QUS index decreased. Pre-screening strategies using QUS T-scores of 0.0, -0.5, -2.0, and -2.5 were dominated by extended dominance, as their incremental cost-effectiveness ratios (ICERs) and incremental cost-utility ratios (ICURs) were higher than that of the next more effective alternative. The cost-effectiveness and cost-utility frontiers included no screening, pre-screening using QUS T-scores of -1.0 and -1.5, and DXA measurement alone.
Conclusion: These results suggest that QUS may be useful as a pre-screening tool for bone densitometry given the limited availability of DXA and health resources, and that the QUS index T-scores of -1.0 and -1.5 are the most appropriate index.