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Mind the gap: National disparities in age-related health problems

GlobalThe age-related health problems of a 76-year-old in Japan and a 46-year-olds in Papua New Guinea have the same level as an ‘average’ person aged 65, with Lesotho and theCentral African Republic performing worst in Africa at 53.6 years. Four of 10 countries with highest age-related burden were African.

"These disparate findings show that increased life expectancy at older ages can either be an opportunity or a threat to the overall welfare of populations, depending on the aging-related health problems the population experiences regardless of chronological age." said Dr. Angela Y Chang, lead author and postdoctoral fellow at the Centre for Health Trends and Forecasts at the University of Washington. "Age-related health problems can lead to early retirement, a smaller workforce, and higher health spending. Government leaders and other stakeholders influencing health systems need to consider when people begin suffering the negative effects of ageing."


The study is the first of its kind, according to Chang, whose centre is housed at the UW's Institute for Health Metrics and Evaluation. Where traditional metrics of aging examine increased longevity, this study explores both chronological age and the pace at which aging contributes to health deterioration. The study uses estimates from the Global Burden of Disease study (GBD).

Researchers measured "age-related disease burden" by aggregating all disability-adjusted life years (DALYs), a measurement of loss of healthy life, related to the 92 diseases. The findings cover 1990 to 2017 in 195 countries and territories. For example, in 2017, people in Papua New Guinea had the world's highest rate of age-related health problems with more than 500 DALYs per 1,000 adults, four times that of people in Switzerland with just over 100 DALYs per 1,000 adults.


Using global average 65-year-olds as a reference group, Chang and other researchers also estimated the ages at which the population in each country experienced the same related burden rate. They found wide variation in how well or poorly people age. Ranked first, Japanese 76-year-olds experience the same aging burden as 46-year-olds in Papua New Guinea, which ranked last across 195 countries and territories. At 68.5 years, the US ranked 54th, between Iran (69.0 years) and Antigua and Barbuda (68.4 years).

Additional findings include:
Age-related disease burden rates decreased over time across all regions between 1990 and 2017, representing reductions in deaths and disease severity of age-related problems. In 2017, people in 108 countries experienced earlier accumulation of problems associated with ageing, whereas those in 87 countries experienced slower onset of aging.

Globally, the age-related diseases with the most deaths and DALYs were ischaemic heart disease, brain haemorrhage, and chronic obstructive pulmonary disease (COPD).

Countries with highest equivalent age to global 65-year-olds in 2017:
1. Japan: 76.1 years
2. Switzerland: 76.1
3. France: 76.0
4. Singapore: 76.0
5. Kuwait: 75.3
6. South Korea: 75.1
7. Spain: 75.1
8. Italy: 74.8
9. Puerto Rico: 74.6
10. Peru: 74.3

Countries with lowest equivalent age to global 65-year-olds in 2017:
1. Papua New Guinea: 45.6 years
2. Marshall Islands: 51.0
3. Afghanistan: 51.6
4. Vanuatu: 52.2
5. Solomon Islands: 53.4
6. Central African Republic: 53.6
7. Lesotho: 53.6
8. Kiribati: 54.2
9. Guinea-Bissau: 54.5
10. Federated States of Micronesia: 55.0

Countries with lowest age-related burden rate in 2017:
1. Switzerland: 104.9 DALYs per 1,000 adults aged 25 or older
2. Singapore: 108.3
3. South Korea: 110.1
4. Japan: 110.6
5. Italy: 115.2
6. Kuwait: 118.2
7. Spain: 119.2
8. France: 119.3
9. Israel: 120.2
10. Sweden: 122.1

Countries with highest age-related burden rate in 2017:
1. Papua New Guinea: 506.6 DALYs per 1,000 adults aged 25 or older
2. Marshall Islands: 396.6
3. Vanuatu: 392.1
4. Afghanistan: 380.2
5. Solomon Islands: 368.0
6. Central African Republic: 364.6
7. Lesotho: 360.5
8. Kiribati: 347.5
9. Guinea-Bissau: 343.4
10. Eritrea: 325.7

Background: Traditional metrics for population health ageing tend not to differentiate between extending life expectancy and adding healthy years. A population ageing metric that reflects both longevity and health status, incorporates a comprehensive range of diseases, and allows for comparisons across countries and time is required to understand the progression of ageing and to inform policies.
Methods: Using the Global Burden of Diseases, Injuries, and Risk Factors Study 2017, we developed a metric that reflects age-related morbidity and mortality at the population level. First, we identified a set of age-related diseases, defined as diseases with incidence rates among the adult population increasing quadratically with age, and measured their age-related burden, defined as the sum of disability-adjusted life-years (DALYs) of these diseases among adults. Second, we estimated age-standardised age-related health burden across 195 countries between 1990 and 2017. Using global average 65-year-olds as the reference population, we calculated the equivalent age in terms of age-related disease burden for all countries. Third, we analysed how the changes in age-related burden during the study period relate to different factors with a decomposition analysis. Finally, we describe how countries with similar levels of overall age-related burden experience different onsets of ageing. We represent the uncertainty of our estimates by calculating uncertainty intervals (UI) from 1000 draw-level estimates for each disease, country, year, and age.
Findings: 92 diseases were identified as age related, accounting for 51·3% (95% UI 48·5–53·9) of all global burden among adults in 2017. Across the Socio-demographic Index (SDI), the rate of age-related burden ranged from 137·8 DALYs (128·9–148·3) per 1000 adults in high SDI countries to 265·9 DALYs (251·0–280·1) in low SDI countries. The equivalent age to average 65-year-olds globally spanned from 76·1 years (75·6–76·7) in Japan to 45·6 years (42·6–48·2) in Papua New Guinea. Age-standardised age-related disease rates have decreased over time across all SDI levels and regions between 1990 and 2017, mainly due to decreases in age-related case fatality and disease severity. Even among countries with similar age-standardised death rates, large differences in the onset and patterns of accumulating age-related burden exist.
Interpretation: The new metric facilitates the shift from thinking not just about chronological age but the health status and disease severity of ageing populations. Our findings could provide inputs into policymaking by identifying key drivers of variation in the ageing burden and resources required for addressing the burden.

Angela Y Chang, Vegard F Skirbekk, Stefanos Tyrovolas, Nicholas J Kassebaum, Joseph L Dieleman

[link url=""]Institute for Health Metrics and Evaluation material[/link]
[link url=""]The Lancet Public Health abstract[/link]

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