Why are these people living the longest?

In a study recently published in Population Studies, researchers measured life expectancy in a new way in 15 countries by using the Lagged Cohort Life Expectancy (LCLE) approach, which accounts for the historical mortality conditions—such as direct conflict and economic depression—that current older generations have lived through. They found that men and women in Australia have among the highest life expectancies in the world. But what contributes to this?

Most traditional measures of life expectancy are based on the mortality rates of a certain time period, but using this approach can provide a skewed calculation of cohort longevity, according to Collin F. Payne, PhD, assistant professor, Demography, The Australian National University, Canberra, Australia, who co-led the study with Michel Guillot, PhD, professor, Sociology, University of Pennsylvania, Philadelphia, PA. In 2016, for example, Australian men had a life expectancy of 80.9 years, just behind Iceland at 81.2 years and Switzerland at 81.3 years via this method, according to the World Health Organization.

“It's basically saying if you took a hypothetical group of people and put them through the mortality rates that a country experienced in 2018, for example, they would live to an average age of 80,” Dr. Payne explained. “But that doesn't tell you anything about the life courses of people, as they've lived through to old age.”

Thus, in the current study, Drs. Payne and Guillot utilized the LCLE approach. Specifically, they categorized individuals by birth year, separating “early” deaths from “late” deaths, to determine the age at which an individual may be considered an “above-average” survivor.

“Our measure takes the life course into account, including mortality rates from 50, 60, or 70 years ago,” said Dr. Payne. “[W]e're comparing a group of people who were born in the same year, and so have experienced similar conditions throughout their [lives].”

The researchers found that Australian men have the highest life expectancy—at 74.1 years—compared with any other group of males in the world. Among women, those in Australia come in a close second with 78.8 years, while their Swiss counterparts trail only slightly ahead with 79.0 years.

Australia’s high ranking among men and women in terms of longevity should come as no surprise, considering that it ranked #7 on Bloomberg’s top 10 Healthiest Countries in the World for 2019, and some researchers have shown that being close to a large body of water or “blue space”—such as an ocean, sea, river, or lake—may significantly reduce mortality and be especially beneficial in older adults. For instance, in a 2018 study that examined the link between exposure to large bodies of water and the risk of mortality, researchers found that “proximity to blue space, and its attendant reduced exposure to a variety of urban stressors (psychosocial, chemical, physical) and…may confer net beneficial effects on physiological systems that integrate stress response.”

The researchers also noted that: “Older and retired people likely spend more time around their homes and therefore have increased opportunities for exposures to residential blue spaces, which may contribute to explaining the [health benefits and reduced risk of mortality] observed among older subjects.”

“Popular belief has it that Japan and the Nordic countries are doing really well in terms of health, wellbeing, and longevity. But Australia is right there,” noted Dr. Payne.

“The results have a lot to do with long-term stability and the fact Australia's had a high standard of living for a really, really long time. Simple things like having enough to eat, and not seeing a lot of major conflict play a part,” he added.

“For example, any Australian man who's above age 74 we know with 100% certainty has outlived half of his cohort—he's an above average survivor compared to his peers born in the same year,” Dr. Payne said. “On the other hand, any man who's died before age 74 is not living up to their cohort's life expectancy.”

By using the LCLE method, the researchers were able to more accurately determine whether an individual was reaching their cohort’s life expectancy. They found that the countries with the highest life expectancy for men following Australia included Sweden (74.0 years), Switzerland (73.7 years), Norway (73.1 years), and the Netherlands (72.6 years).

For women, Switzerland, as previously mentioned, ranked highest, possibly due to the country’s superior healthcare system, which is considered to be the best in the world. Other countries with the highest life expectancy for women were ranked as follows: Australia (78.8 years), Norway (78.6 years), Sweden (78.4 years), and the Netherlands (78.2 years).

Men and women in United States fared favorably, with estimated life expectancies of 71.6 and 76.1, respectively. Surprisingly, Italy—given its Mediterranean culture and second-place rank on Bloomberg’s list of top 10 healthiest countries—came in last place for women (72.1 years). On the flip side, Portugal had the lowest life expectancy for men (64.8 years).

Although a number of factors contributed to Australia earning top spots in the new rankings, mortality due to war-time conflict in other countries seemed to be the primary driver in the boost. For instance, where mortality was particularly high in Japan and France in the 1930s through the 1950s—largely due to World War II—these rates were relatively low in Australia. Of note, the estimated life expectancy in France was calculated to be 68.8 years for men and about 77.0 years for women, while those for Japan were 68.5 for men and 72.9 for women.

Because the LCLE approach is based on the average years of life remaining at a given age for people born in the same year vs period life expectancy (based on the risks experienced by different cohorts during a single time period, which can underestimate expected life spans), Dr. Payne is working on collecting enough data to further study how rankings have changed over the past 30-40 years.