Cost-Utility Analysis of Bracing vs. Observation for Adolescent Idiopathic Scoliosis

From the 2021 HVPAA National Conference

Ijezie Ikwuezunma (Johns Hopkins School of Medicine), Kevin Wang, Adam Margalit, Paul Sponseller, Amit Jain

Background

There is high quality evidence that bracing can prevent radiographic progression of spinal curvature in skeletally immature adolescent idiopathic scoliosis (AIS) patients with curves between 25-45°. Despite popular use, the cost-utility of bracing has not been established.

Objective

This study aimed to determine the cost-utility of bracing in AIS.

Methods

A decision-analysis model was developed for a hypothetical, 10-year old girl, Risser 1, Sanders 3, with a 35° main thoracic curve who could be treated with 2-years of bracing vs. observation. We estimated the probability, cost, and quality-adjusted life years (QALY) for each life event based on comprehensive review of the AIS literature. Costs were reported in terms of 2020 real dollars. QALYs were discounted at 3%. Incremental net monetary benefit (INMB) was calculated based on a probabilistic sensitivity analysis using Monte Carlo simulations of 1,000 hypothetical patients. One-way sensitivity analyses were performed by varying model inputs.

Results

Our decision-analysis model revealed that bracing was the dominant treatment choice over observation at $50,000/QALY willingness to pay threshold. The net lifetime costs (assuming mean life expectancy 79 years) were $57,908 ± $5,443 with bracing and $79,079 ± $4,281 with observation. The net lifetime QALYs were 24.1± 1.9 with bracing and 23.8 ± 1.8 with observation. Bracing was favored in 99.6% of the simulations with a median INMB of $32,854 (95% CI, $13,695 to $45,689). The model was most sensitive to the impact of bracing vs. observation on the probability.

Conclusion

Cost-utility analysis demonstrates that bracing for AIS is dominant over observation, with a positive INMB.

Clinical Implications

Bracing is effective for preventing curve progression in skeletally immature AIS patients, and is the dominant choice in cost-utility analysis.