Characterizing patterns in causes, risk factors, and life expectancy among the oldest old (aged 95+ years)

Abstract

Background: The global population is aging rapidly, extending into the oldest old. However, increased longevity does not always translate into enhanced health. While genetic and environmental factors influence lifespan, evidence indicates that targeted interventions can substantially enhance the likelihood of reaching 100 years. This study aimed to characterize disease and risk factor patterns among the oldest-old to identify actionable targets for promoting health and functional capacity in this rapidly growing population.

Methods: This study identified 18 countries with the largest populations aged 95 years and older using data from the Global Burden of Disease (GBD) 2023 study and the United Nations World Population Prospects 2024. Disability-adjusted life years (DALYs), years of life lost (YLLs), and years lived with disability (YLDs) from 1990 to 2023 were quantified, ranked, and visualized across three major cause categories (non-communicable, communicable and nutritional diseases, and injuries) and risk factors (behavioral, environmental/occupational, and metabolic) by using the GBD 2023 estimates. Temporal trends were assessed using estimated annual percentage change derived from log-linear regression models, calculated separately for periods before and after the COVID-19 pandemic peak. K-means clustering was employed to identify cross-country burden patterns, with the optimal number of clusters determined via the silhouette method. Temporal trends in health-adjusted life expectancy (HALE) were examined, and frontier analysis was applied to estimate the potential for further HALE improvement across countries.

Results: From 1990-2023, the absolute disease burden among individuals aged 95 + years increased more than fivefold, primarily driven by non-communicable diseases, accounting for ∼86 % of the total DALYs. Ischemic heart disease remained the leading cause, particularly for YLLs, followed by Alzheimer's disease and other dementias, which predominated in YLDs, followed by stroke and chronic kidney disease. During the COVID-19 pandemic peak (2019-2021), mental health disorders, including depression and anxiety, demonstrated a marked increase. Cluster analysis in 2023 revealed two distinct national patterns: one dominated by acute cardiovascular conditions and the other by chronic multi-system diseases. Absolute burdens of metabolic, behavioral, and environmental/occupational risk factors increased over time, although their relative contributions declined; high systolic blood pressure (YLLs), high fasting plasma glucose (YLDs), and kidney dysfunction remained the leading risk factors. The average HALE increased from 1.86 years in 1990-2.16 years in 2019, declined during the pandemic, and partially recovered by 2023. Frontier analysis indicated nearly a twofold potential for further HALE improvement under current socioeconomic conditions.

Conclusion: The 95 + -year-old population exhibits distinctive patterns of disease burden that have shifted substantially over the past three decades. Despite cross-national differences, cardiometabolic diseases and risk factors, along with multisystem comorbidities from the brain and kidneys, remain the primary drivers. Integrated strategies addressing biological, social, and environmental factors may enhance intrinsic capacity and promote healthy aging in the oldest old.

Keywords: Causes; Global burden of diseases; Life expectancy; Oldest old (95 + years); Risk factors.