Nature Aging: In the model, reducing diseases whose burden increases with age produces increasing returns
Nature Aging: In the model, reducing diseases whose burden increases with age produces increasing returns
The authors divided causes of disease into four groups according to how their burden changes over the life course. For a newborn, the group with an age-related increase in burden accounts for the greatest expected loss of healthy life in countries at every income level.
On 2 September, researchers reported in an article in Nature Aging a method for grouping diseases according to how their burden changes across the life course. They analyzed data from the Global Burden of Disease study for 1990–2023, comparing 304 causes of disease and injury across 204 countries by the number of years of life lost to premature death and disability. This analysis produced four statistical groups: diseases of infancy, diseases of early adulthood, diseases of later adulthood, and diseases whose burden generally increases with age.
The last group included ischemic heart disease, dementia, Parkinson's disease, type 2 diabetes, chronic obstructive pulmonary disease, chronic kidney disease, and some cancers. These conditions share the same general shape of the age-specific burden curve, although their causes may differ.
This cluster now accounts for the largest share of mortality, disability, and their combined burden worldwide. For a newborn, it also accounts for the greatest expected loss of healthy life in countries at every income level. In low-income countries, its lead over diseases of infancy almost disappears: 9.05 years of healthy life compared with 9.03. The lifetime calculation accounts for the probability of surviving to each age, so it differs from a cross-sectional estimate based on the current population.
The authors also modeled a sustained reduction in the prevalence of each disease group. Their global health measure sums the years of healthy life experienced by people of all ages while accounting for how many people survive to each age. Lower disease prevalence improves health immediately, while lower mortality allows more people to survive to later ages. For diseases whose burden increases with age, mortality and disability occur at similar stages of life, so the benefits of these two changes overlap.
In a hypothetical calculation for 2050, reducing the prevalence of this group by 50% produced a total gain 2.2 times larger than a 25% reduction. Complete elimination produced a gain 5.9 times larger. For the other three groups, the effect remained close to linear. The first reduction allows more people to reach the ages at which the next reduction adds even more healthy years.