Economic evaluation of school scoliosis screening in Gannan Tibetan autonomous prefecture, Gansu Province: a cost-utility analysis based on decision tree-Markov model

Objective This study evaluates the cost-utility of school-based scoliosis screening for adolescents in resource-limited settings to inform regional school health and disease control policies. Methods We performed a model-based cost-utility analysis using real-world data from a screening program in Gannan Tibetan Autonomous Prefecture, Gansu Province. A decision tree linked to a Markov cohort model compared “organized school-based screening” with “no organized screening, relying on opportunistic detection.” The model simulated a cohort of in-school adolescents until skeletal maturity over a 4-year baseline horizon, using 3-month Markov cycles. Health states were stratified by adolescent idiopathic scoliosis severity: mild, moderate (with or without bracing), severe (awaiting surgery), and post-operative stable. Adopting a healthcare system perspective, we estimated costs and quality-adjusted life years (QALYs), applying a 5% annual discount rate. Parameter uncertainty was assessed via deterministic and probabilistic sensitivity analyses. Results In the base-case analysis, the screening strategy dominated the opportunistic detection strategy, yielding a lower discounted per-person cost and a minimal discounted QALY gain of 0.000005. The incremental net monetary benefit was 58.33 CNY per person at a willingness-to-pay threshold of 52,825 CNY/QALY. Probabilistic sensitivity analysis showed most iterations in the cost-saving quadrant of the cost-utility plane, with incremental QALYs near zero, confirming the strategy’s robust cost-saving potential across parameter uncertainties. The results were most sensitive to the assumed proportion of undiagnosed cases without screening, followed by surgical costs and disease progression probability. Scenario analysis indicated a more pronounced cost-saving advantage in regions with weaker routine diagnostic capacity. Conclusion From a healthcare system perspective, school-based adolescent scoliosis screening in resource-limited settings can be cost-saving during adolescence. The primary economic benefit arises from reducing progression to severe disease and avoiding high-cost surgeries. The limited modeled QALY gain likely reflects the short analytical horizon, which inadequately captures potential long-term quality-of-life benefits related to body image, mental health, and functional outcomes in adulthood.