Cost-effectiveness analysis of surgical proximal femur fracture prevention in elderly: a Markov cohort simulation model

Abstract

Background: Hip fractures are a common and costly health problem, resulting in significant morbidity and mortality, as well as high costs for healthcare systems, especially for the elderly. Implementing surgical preventive strategies has the potential to improve the quality of life and reduce the burden on healthcare resources, particularly in the long term. However, there are currently limited guidelines for standardizing hip fracture prophylaxis practices.

Methods: This study used a cost-effectiveness analysis with a finite-state Markov model and cohort simulation to evaluate the primary and secondary surgical prevention of hip fractures in the elderly. Patients aged 60 to 90 years were simulated in two different models (A and B) to assess prevention at different levels. Model A assumed prophylaxis was performed during the fracture operation on the contralateral side, while Model B included individuals with high fracture risk factors. Costs were obtained from the Centers for Medicare & Medicaid Services, and transition probabilities and health state utilities were derived from available literature. The baseline assumption was a 10% reduction in fracture risk after prophylaxis. A sensitivity analysis was also conducted to assess the reliability and variability of the results.

Results: With a 10% fracture risk reduction, model A costs between $8,850 and $46,940 per quality-adjusted life-year ($/QALY). Additionally, it proved most cost-effective in the age range between 61 and 81 years. The sensitivity analysis established that a reduction of ≥ 2.8% is needed for prophylaxis to be definitely cost-effective. The cost-effectiveness at the secondary prevention level was most sensitive to the cost of the contralateral side's prophylaxis, the patient's age, and fracture treatment cost. For high-risk patients with no fracture history, the cost-effectiveness of a preventive strategy depends on their risk profile. In the baseline analysis, the incremental cost-effectiveness ratio at the primary prevention level varied between $11,000/QALY and $74,000/QALY, which is below the defined willingness to pay threshold.

Conclusion: Due to the high cost of hip fracture treatment and its increased morbidity, surgical prophylaxis strategies have demonstrated that they can significantly relieve the healthcare system. Various key assumptions facilitated the modeling, allowing for adequate room for uncertainty. Further research is needed to evaluate health-state-associated risks.

Keywords: Cost-effectiveness; Finite-State Markov Model; Geriatric; Healthcare utilization; Hip fractures; Prevention; Prophylaxis; Quality-adjusted life-year; Sensitivity analysis; Surgical Prophylaxis.

Fig. 1

Model design for models A & B showing the health states (Ellipses) and the transition probabilities (Arrows). A cohort of identical individuals enters the Markov model and transitions through different health states with their correlated costs and QALYs

Fig. 2

Model A: One-way worst-case scenario sensitivity analysis comparing changes in the ICER concerning age. The fracture risk used in this analysis was the lowest risk that we could obtain from the FRAX tool. The age range where secondary surgical prophylaxis is most cost-effective can be clearly seen on this figure

Fig. 3

Model A: Two-way sensitivity analysis comparing the risk reduction after prophylaxis with different ages. The red area indicates that the ICER is less than $50,000/QALY, given the selected parameters. At the assumed 10% risk reduction after prophylaxis, it will be definitely cost-effective at the maximum age of 71 years

Fig. 4

Model B: The ICER variations in terms of changes in the model parameters in the pre-defined range. Heading towards the low parameter range is represented by the bar’s grey section, while the dark section represents the high parameter range. The parameters are sorted from the most considerable effect on the ICER to the lowest. The remaining parameters that had an insignificant effect on the ICER within the defined range were removed from this diagram. The expected value (EV) line is the value where all bars are centered. It portrays the ICER for model B using the lower fracture risk. The WTP threshold line is shown as the vertical dotted line

Fig. 5

Model B: Two-way sensitivity analysis observing changes in the cost-effectiveness regarding the individual’s age and the risk reduction after prophylaxis. The red area indicates that the ICER is less than $50,000/QALY, given the selected parameters. For instance, at 15% risk reduction, the maximum age where it will be definitely cost-effective is 64 years