Multimorbidity continues to accumulate and diversify well into extreme old age, with disease accumulation accelerating up to age 80, stabilizing between 80 and 90, and decelerating thereafter, driven primarily during non-terminal years of life.
Key Findings
Results
Disease accumulation accelerated up to age 80, stabilized between ages 80 and 90, and decelerated thereafter, though disease burden and complexity continued to increase into extreme old age.
Study population comprised all individuals born in 1920–1922 who survived to age 70, using nationwide Swedish register data.
The pattern of acceleration followed by stabilization and deceleration was observed across the age range of 70 to 100.
Despite slowing accumulation rate after age 90, both disease burden and complexity continued to increase.
The study tracked population-level trajectories rather than individual disease trajectories.
Results
By age 90, the mean number of diseases was 3.9 in men and 3.5 in women.
Men had a higher mean disease count (3.9) than women (3.5) at age 90.
Data were derived from nationwide Swedish register data covering birth cohorts 1920–1922.
This figure represents population-level averages among survivors to each age.
Results
More than half of individuals aged 95 and older had five or more diseases.
Over 50% prevalence of five or more diseases was observed at age ≥95.
This finding indicates high disease complexity at extreme old age.
The cohort studied included all individuals born 1920–1922 surviving to age 70, followed across the full age range to 100.
Results
Most disease accumulation occurred during non-terminal years of life rather than in the period immediately preceding death.
The study specifically quantified contributions of proximity to death versus non-terminal periods to disease accumulation.
This finding suggests that multimorbidity in late life is primarily accumulated outside of terminal illness phases.
The authors note this has 'important implications for geriatric care.'
Results
Cardiovascular disease was the dominant contributor to multimorbidity throughout the age range studied, while musculoskeletal and neurosensorial diseases became increasingly important at advanced ages.
Disease composition analysis tracked the relative contributions of different disease categories from ages 70 to 100.
Musculoskeletal and neurosensorial diseases showed growing relative importance at advanced ages.
The changing disease composition reflects an increasingly complex, cross-system disease pattern in extreme old age.
Survivorship, proximity to death, and disease composition were all assessed as contributors to multimorbidity dynamics.
Results
Multimorbidity increased substantially between ages 70 and 100 and continued to diversify well into extreme old age.
The study characterized population-level trajectories across a 30-year age range (70–100).
Disease complexity, not just number of diseases, continued to grow at extreme old age.
Multimorbidity was described as 'increasingly characterized by complex, cross-system disease patterns.'
The study used nationwide register data from Sweden, providing complete population coverage for the birth cohorts studied.
What This Means
This research tracked how multiple chronic diseases accumulate in a population of older adults from age 70 to 100, using health records from everyone in Sweden born between 1920 and 1922 who reached age 70. The researchers found that the rate at which people acquired new diseases sped up until around age 80, then leveled off between 80 and 90, and slowed down after age 90 — but importantly, the total number of diseases and the complexity of disease combinations kept increasing all the way into very old age. By age 90, people had on average nearly 4 diseases, and more than half of those reaching age 95 or older were living with five or more conditions.
A key finding was that most of this disease accumulation happened during the non-terminal years of life — meaning the bulk of multimorbidity built up well before the final phase of life, not primarily as people were approaching death. Heart and cardiovascular diseases were the biggest contributors throughout old age, but joint, bone, and sensory diseases (like hearing and vision problems) became increasingly important in the oldest age groups. The mix of diseases also became more varied and spread across different body systems as people aged.
This research suggests that the complexity of managing multiple diseases in elderly populations does not simply plateau or resolve as people reach very advanced ages — it continues to grow. This has practical implications for how healthcare systems plan and deliver care to older adults, pointing to the need for integrated, multi-condition care approaches that remain relevant even for people in their 90s and beyond, and not just for those near the end of life.
Zhang Y, Ebeling M, Schmidt-Mende K, Drefahl S, Modig K. (2026). Slowing disease accumulation but persistent complexity: population-level multimorbidity dynamics in old age.. Age and ageing. https://doi.org/10.1093/ageing/afag268