A new Japanese model presents a more accurate way to calculate the value of health, age and longevity.
Living longer has always been one of humanity’s success stories. Vaccines, antibiotics, safer cities and better nutrition have pushed average life expectancy upward across the globe. Yet this success carries a mystery: the longer we live, the more pressure we place on healthcare systems, especially when extra years are lived in poor health.
Japan knows this so well. With one of the world’s longest life expectancies, the country is also facing a future in which healthcare spending is projected to nearly double by 2040. The question facing policymakers is no longer just how to extend life, but how to decide which health interventions are truly worth the investment.
That decision often comes down to a deceptively simple metric: the quality-adjusted life year, or QALY [1].
QALYs are designed to measure both how long people live and how well they live. They are used globally to assess whether a treatment, drug or policy offers good value for money. In practice, however, most systems treat a healthy year as a fixed unit, worth the same regardless of who receives it.
A year of good health for a 20-year-old is counted the same as a year of good health for an 80-year-old.
That assumption keeps models tidy, but it glosses over lived reality. Health needs shift with age. Remaining life expectancy shrinks. The meaning of “one more good year” changes as people move through life. Flattening all of this into a single number may be convenient, but it risks distorting resource allocation, especially in aging societies.
A research team led by Professor Ryuta Takashima of Tokyo University of Science believes there is a better way. In a study published in Scientific Reports in December 2025, the researchers introduced a new framework that adjusts the value of a QALY based on age and how quality of life changes over time [1].
Rather than discarding existing economic tools, the team built on the “value of a statistical life” (VSL), a measure commonly used to estimate how much society is willing to pay to reduce the risk of death. By linking VSL to different life stages and health trajectories, they derived a QALY value that varies with age rather than remaining frozen.
“Our findings help clarify the value of extending healthy lifespan according to QoL and age, making it possible to present measures for the rational allocation of medical resources,” Takashima explains [2].
When the model was applied to Japanese socioeconomic data, several insights emerged.
First, the familiar benchmark still holds, on average. Japan’s commonly cited QALY value of around 5 million JPY aligns with the study’s overall estimate. But beneath that average lies wide variation. For younger individuals, health policies must be relatively inexpensive per QALY to be considered cost-effective. For older populations, higher-cost interventions can still make economic sense.
This suggests that the perceived benefit of gaining additional life expectancy increases with age. Older individuals tend to recognise the value of extra healthy time earlier and more acutely than younger people do.
Second, the study sheds light on the economic upside of staying healthy for longer. When individuals maintain a high quality of life across more years, the monetary value of gaining one additional year of perfect health actually falls. This is not a contradiction. It reflects a healthier population overall, where marginal gains require fewer resources and generate less downstream cost.
The third finding may be the most policy-relevant. By modelling cost-reduction effects, the researchers showed that policies that extend healthy life expectancy can significantly reduce total healthcare spending. Shifting more people toward scenarios where health declines slowly, not sharply, lowers the average QALY value and reduces the budget required to achieve population-wide health gains.
In other words, preventing decline is cheaper than managing it later. Investing early in healthspan pays off not only in human terms but also financially.
While Japan serves as a model case, the framework is not country-specific. Because it can be recalculated using local demographic and economic data, it offers a tool for any region grappling with aging populations and falling birth rates.
“In a future world of aging populations and declining birth rates, the intrinsic value of the QALY is likely to increase over time,” Takashima notes, adding that Japan’s experience may foreshadow global demographic shifts [2].
It is that progress is no longer just about adding years to life. It is about understanding when those years matter most, how health is distributed across the lifespan and how smarter measurement can unlock more sustainable systems. Longevity, viewed this way, becomes not just a biological goal, but an economic one.
[1] https://www.nature.com/articles/s41598-025-29794-6
[2] https://www.tus.ac.jp/en/mediarelations/archive/20260108_1854.html
