The US has the lowest life expectancy of high-income English-speaking nations, while Australia continues to lead the pack with the highest. Poverty and poor health are big influences on the differing outcomes, but a major factor is also the number of young Americans dying from drug abuse, car accidents, and guns, researchers say.

Researchers from the University of Southern California and Pennsylvania State University compared life expectancy in six Anglophone countries – the US, Canada, Ireland, the United Kingdom, Australia, and New Zealand – between 1990 and 2019. 

They broke down the data by sex, age, and 18 causes of death categories, including a range of diseases plus "preventable deaths" like accidents and overdoses. 

Australia has led the English-speaking world in life expectancy for the last three decades and these findings suggest they’re still top of the class. As per the recent findings, life expectancy for men in Australia, the best-performing country, was 4.75 years higher than in the US, the worst-performing country. 

"One of the main drivers of why American longevity is so much shorter than in other high-income countries is our younger people die at higher rates from largely preventable causes of death, like drug overdose, car accidents and homicide," study co-author Jessica Ho, associate professor of sociology and demography at Penn State, said in a statement.

It’s also noteworthy that Americans also suffer from higher rates of cardiovascular disease mortality, impacting the life expectancy of middle-aged people. 

“Some of the latter could be related to sedentary lifestyle, high rates of obesity, unhealthy diet, stress and a history of smoking. It’s likely that these patterns of unhealthy behaviors put Americans at a disadvantage in terms of their health and vitality,” Ho explained.

The data also indicated that the US has huge geographical inequalities across different parts of the country. California and Hawai'i had some of the highest life expectancies at birth, with women averaging 83 to 83.9 years and men averaging 77.5 to 78.4 years. On the other hand, the American Southeast had some of the lowest life expectancies at birth, with women averaging 72.6 to 79.9 years and men averaging 69.3 to 74.4 years.

Another interesting tidbit: the UK dropped to the second worst-performing country in recent years, while Ireland showed the largest gains in life expectancy, with men's lifespans increasing by approximately 8 years and women's lifespans by more than 6.5 years. 

The study provides a few pointers for high-income Anglophone countries looking to increase their life expectancy: be more like Australia. Australia does have the second-highest obesity rate of the group, but it does have relatively low rates of smoking, gun ownership, and drug-related mortality, all of which the study credits to “strong public health efforts.”

“What the study shows is that a peer country like Australia far outperforms the US and was able to get its young adult mortality under control. It has really low levels of gun deaths and homicides, lower levels of drug and alcohol use and better performance on chronic diseases, the latter of which points to lifestyle factors, health behaviors and health care performance,” said Ho.

"Australia is a model for how Americans can do better and achieve not only a higher life expectancy but also lower geographic inequality in life expectancy," she added.

The new study is published in the journal BMJ Open.