Cost-effectiveness of treatment of women aged 70 years and older with both osteopenia and microstructural deterioration

Objective
Treatment is usually withheld from women with osteopenia even though they are the source of over 70% of all women having fragility fractures. As microstructural deterioration increases fracture risk and zoledronate reduces it, we aimed to determine whether identifying and treating women with osteopenia and severe microstructural deterioration is cost-effective. We also compared the health economic outcomes of ‘global’ versus ‘targeted’ treatment using SFS of women aged ≥70 years with osteopenia.

Design
We assessed the cost-effectiveness from using a Markov model that simulated 10-year follow up of women with osteopenia. Decision analysis compared measurement of distal radial microstructure using high resolution peripheral computed tomography (at a cost of USD $210) to target women with severe microstructural deterioration for zoledronate treatment, compared to standard care defined as measurement of bone mineral density (BMD) with treatment recommended when femoral neck BMD T score is ≤−2.5 SD with or without a prevalent fracture. In the ‘global’ treatment approach, high resolution peripheral quantitative tomography (HRpQCT) was not undertaken.

Setting
US healthcare system.

Participants
A hypothetical cohort of 1000 women aged ≥70 years with osteopenia and no previous fractures was studied.

Measures
Fractures, deaths, years of life lived, quality-adjusted life years (QALYs) lived and costs. Data inputs were obtained from published sources. A 3% annual discount rate was applied to future health benefits and costs.

Results
Women in the standard care group incurred 327 fractures during 7341.0 years and 4914.2 QALYs lived. Women in the intervention group incurred 300 fractures (number needed to treat 37) during 7359.2 years and 4928.8 QALYs lived. Net costs were USD $4,862,669 and $4,952,004, respectively, equating to 18.1 years of life saved and 14.6 QALYs saved, and incremental cost-effectiveness ratios of $4992 per year of life saved and $6135 per QALY saved. These ratios are well within the threshold considered to be cost-effective. Sensitivity analyses indicated the results were robust.

Relative to standard of care, ‘global’ and ‘targeted’ treatment respectively resulted in 0.0364 vs. 0.0181 years of life (YoLS) saved per person, and 0.0292 and 0.0146 QALYs saved per person. The net costs per person for the respective approaches were $US 359 and $US 89. The incremental cost-effectiveness ratios were $9864 per YoLS and $12,290 per QALY saved for the ‘global’ approach and $4992 per YoLS and $6135 per QALY saved for the ‘targeted’ approach.

Conclusion
Identifying and treating women ≥70 years of age with osteopenia and microstructural deterioration with zoledronate cost-effectively reduces the morbidity and mortality imposed by fragility fractures. This ‘targeted’ approach is more cost-effective than a ‘global’ approach and incurs only 25% of total costs.

Implication
Women with osteopenia with bone fragility due to microstructural deterioration should be identified and targeted for treatment.

Summary
Women with osteopenia have 70% of fractures. Treating those with microstructural deterioration conferred an incremental cost-effectiveness ratio of $4992/year of life saved and $6135 per QALY saved.