デュシェンヌ型筋ジストロフィーの症例研究：費用対効果分析における延命の逆説

Traditional quality-adjusted life-year (QALY)-based cost-effectiveness analyses (CEAs) may inadvertently penalize treatments extending survival in populations with disabilities. Duchenne muscular dystrophy (DMD) is a rare, progressive disease diagnosed during childhood with significant morbidity, premature mortality, and considerable healthcare costs. The impact of delaying mortality on CEAs for DMD is unclear.

To evaluate the impact of delaying nonfatal progression and/or mortality using a QALY-based CEA for three hypothetical DMD treatments, assessing if treatment value increases by delaying morbidity and/or mortality.

A previously published, five-state QALY-based cost-effectiveness model for analyzing treatments in an early ambulatory DMD population was replicated, validated, and adapted to include an early nonambulatory (ENA) population. Maximum annual treatment price was determined for three hypothetical treatments individually compared for each population with standard of care (SoC): (A) delays nonfatal progression and mortality; (B) delays nonfatal progression; or (C) delays mortality. A 10-year delay was assessed for all three. Willingness-to-pay (WTP) thresholds ranged from $50\hspace{0.17em}000to$ 200 000/QALY.

In both populations, QALYs gained vs SoC were highest for the hypothetical treatment delaying both nonfatal progression and mortality. Maximum annual treatment price was highest for the hypothetical treatment delaying nonfatal progression only (both populations and all WTP thresholds). Delaying mortality alone consistently had a negative annual valuation (not cost-effective even at $0price),rangingfrom$ -8685 to $-2148\left(EApopulation\right)and$ -13 253 to $-3278 (ENA population). For all treatments, valuation for the ENA population was consistently lower.

These model results illustrate that delaying both nonfatal progression and mortality is less valuable in a traditional CEA than delaying nonfatal progression alone, even when the additional survival is at the patient's best possible health and lowest costs. These results emphasize the significant shortcomings of QALY-based CEAs for assessing the value of potential life-extending treatments for progressive, disabling diseases, like DMD.

These results suggest that within a traditional CEA, delaying mortality decreases a DMD treatment's value estimate, countering society's values and norms for desired life extension in vulnerable populations. These limitations must be carefully considered when interpreting model results and highlight the need for applying other value assessment methodologies.