Every government faces the same brutal calculation: when healthcare budgets are finite, how do you decide which treatments to fund and which to deny? For decades, the answer has been a single number, a fixed price for one year of perfect health. In Japan, that number sits at roughly 5 million yen. A treatment that costs more per healthy year gained typically gets rejected. One that costs less gets approved.
Researchers from Tokyo University of Science now argue this approach contains a fundamental flaw. A year of good health at 25 does not carry the same economic weight as a year at 85, and pretending otherwise quietly distorts how medical resources get allocated across an aging population.
In research published in Scientific Reports, a team led by Professor Ryuta Takashima built a framework that adjusts the value of a quality-adjusted life year (the QALY) based on age and realistic health trajectories. They calculated how that value shifts across different life stages using Japanese wage data, consumption patterns, and survival rates.
The pattern cuts against intuition. The monetary value of a QALY actually rises with age. For someone in their 20s, an additional healthy year might be worth 3 to 4 million yen. For someone in their 80s, that same year could exceed 9 million yen. The difference stems partly from discounting (future gains are worth less than immediate ones) but also from how older adults experience the benefit of extended life expectancy more directly.
Four Paths Through Aging
To make their estimates realistic, the researchers modeled how quality of life typically changes over a lifetime. One scenario assumes a slow, steady decline starting at 50. Another reflects a sharp health drop at 60, perhaps from chronic illness, followed by stabilization. A third shows gradual deterioration across the entire lifespan. The fourth represents relatively stable health until a steep decline near the end.
By running these scenarios through economic models based on the value of a statistical life (a standard measure of what society will pay to reduce mortality risk), the team calculated age-specific QALY values for each trajectory. Across all four, the pattern held. Older people, higher value per healthy year.
Current policy may quietly bias decisions as a result. Using a flat QALY threshold of 5 million yen might reject cost-effective interventions for older adults while approving inefficient ones for younger populations. In an aging society, that distortion compounds.
The research also uncovers something less obvious. When populations maintain better health for longer, the monetary value of an additional perfect health year actually falls. Not because health matters less, but because gains spread across a longer, healthier lifespan. In populations where people stay robust well into old age, adding one more year delivers smaller marginal benefit than where decline starts earlier.
Paying Less by Staying Healthier
Investments that successfully extend healthy life expectancy can reduce overall healthcare costs, even when people live longer. When more individuals follow healthier aging paths, governments achieve population-level health gains at lower cost per QALY. Prevention changes the economic baseline.
“Our findings help clarify the value of extending healthy lifespan according to quality of life and age, making it possible to present measures for the rational allocation of medical resources,” Takashima explains.
The framework can be adapted anywhere by plugging in local demographic and economic data. As populations age globally, the question of how to value health gains will only intensify. The study does not argue some lives matter more than others. It shows how crude assumptions ripple through funding decisions, quietly shaping which treatments get approved.
A treatment costing 6 million yen per healthy year might be rejected today because it exceeds the standard threshold. But if that intervention targets older adults, where a healthy year is worth 9 million yen, rejecting it wastes potential value. In a future defined by longer lives and constrained budgets, a more flexible view of what a healthy year is worth could help policymakers manage aging not as an inevitable cost, but as a variable they can shape.
Scientific Reports: 10.1038/s41598-025-29794-6
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