A study published last month in The Lancet Public Health examined health data from 204 countries and territories spanning 1990 to 2023. It confirmed the thing most people already suspect but rarely see quantified: we are getting very good at extending how long people live, and substantially less good at ensuring those additional years are worth living.
The study, led by researchers at the Institute for Health Metrics and Evaluation (IHME) in collaboration with the National University of Singapore, introduced a specific measure for this divergence: the morbidity gap. Defined as the difference between total life expectancy and healthy life expectancy, it captures what gets lost when medicine succeeds at preventing death while failing to prevent the chronic conditions that erode quality of life.
In 203 of 204 countries analyzed, that gap grew larger between 1990 and 2023. One country improved. Every other measured nation is spending a larger proportion of its citizens' lives in poor health than it was 33 years ago.
The Singapore Paradox
Singapore makes the most instructive case study precisely because it is the global leader. As BBC Science Focus reports, the average Singaporean is now expected to live beyond their 85th birthday — the longest life expectancy of any country in the world. Singapore also leads in healthy life expectancy: 74.1 years.
These are extraordinary numbers. They are also revealing about what remains unsolved. Singaporeans now spend an average of 11.2 years at the end of their lives in poor health — a larger stretch of illness and disability than the country recorded in the 1990s. The healthspan-to-lifespan gap has widened even as both numbers improved.
"Living longer does not automatically mean that every additional year is lived in good health," said Dr. Marie Ng, associate professor at NUS Medicine and co-author of the study. "The next frontier is therefore not simply to add more years to life, but to reduce the burden of chronic illness, disability, and functional decline across the life course."
What the Morbidity Gap Actually Measures
Healthy life expectancy (also called HALE) differs from total life expectancy in that it accounts for the burden of disease — years lived with chronic illness, disability, or functional limitation are weighted to reflect their reduced quality. The difference between these two numbers is the morbidity gap.
Globally, life expectancy rose from 64.6 years in 1990 to 73.8 years in 2023. Healthy life expectancy did not keep pace. Adults now spend roughly one in every seven years of their lives in poor health — a proportion that has been growing.
The gender dimension of this data is particularly striking. Women globally outlive men — but they pay for those extra years disproportionately. The global morbidity gap averages 12.1 years for women, compared with 9.3 years for men. In Singapore, the contrast is sharp: women live just 4.4 years longer than men on average, but spend more than twice as many of those years in poor health — 21.1 years versus 10.4 for men.
Living longer, in the data, is not the same thing for both sexes.
Why 203 of 204 Countries Are Getting Worse
The mechanism behind the growing morbidity gap is, in some sense, a product of medicine's success. Modern medicine has become very effective at preventing death from conditions — cardiovascular disease, certain cancers, diabetes complications — that used to kill people but now become managed, chronic illnesses that persist for years or decades. We are surviving things that previous generations died from. We are then living with those things.
The principal drivers of the morbidity gap are noncommunicable diseases: cardiovascular conditions, type 2 diabetes, cancer, musculoskeletal disorders, and — particularly in wealthy countries — mental health conditions and neurological disease.
These are not random. They are significantly influenced by modifiable factors: diet, physical activity, sleep, social connection, chronic stress, and the management of blood pressure, blood sugar, and other metabolic markers. The lifestyle decisions being made by people in their 40s and 50s today are, in measurable ways, calibrating how many of their later years will be healthy and how many will not.
The US Outlier
The United States emerges from the data as an outlier — not in a flattering direction. Among high-income countries, the US has the largest morbidity gap. Americans spend more of their lives in poor health, as a proportion of their total lifespan, than citizens of comparable wealthy nations.
The primary drivers in the US case: mental health disorders, substance use disorders, and musculoskeletal conditions. These are not primarily products of aging. They are products of how Americans live — and they compound, in the data, into a health burden that other rich countries have managed more effectively.
The question the Lancet study ultimately poses isn't about how long you will live. It's about what proportion of those years will be yours in any real sense — active, functional, free of significant illness. That proportion, in most of the world, is shrinking. Whether it shrinks for any individual depends substantially on choices being made right now.
