The gap in life expectancy between U.S. men and women grew to its largest in 25 years in 2021, largely driven by men being more likely to die from COVID-19 and drug overdoses, according to a new study by UCSF and Harvard researchers. 

The research, published Wednesday in JAMA Internal Medicine, analyzed life expectancy data from the U.S. Centers for Disease Control and Prevention and sought to explain why the gap is widening between men and women. In 2021, this gap grew to 5.8 years — up significantly from a low of 4.8 years in 2010.

In 2021, the most recent year for which data are available, women lived an average of 79.3 years, and men lived an average of 73.5 years.Overall life expectancy dropped for the second consecutive year, from 78.8 years in 2019 to 77 in 2020 and 76.4 in 2021. 

Women have outlived men for more than a century, attributable to higher rates of cardiovascular and lung cancer deaths in men linked to smoking, the study noted. That gap began to narrow in the 1980s, following public health campaigns about the dangers of smoking, and continued to narrow until 2010. After that, it began widening again, said Dr. Brandon Yan, the study’s first author and a resident physician at UCSF.

“So the question we had was why is this disparity that had been improving for the last three decades now worsening?” Yan said.

Two major events from the last few years appear to have exacerbated the disparity: COVID was more likely to kill men for a number of reasons, including men being more likely to work in jobs where they could be exposed to the virus, such as agriculture, and higher rates of incarceration and homelessness among men compared to women. Despite similar rates of COVID infection between men and women, men were more likely to die and have severe cases because of higher rates of comorbidities like diabetes, heart disease and obesity.

And drug overdoses, particularly opioid overdoses, were more likely to kill men than women.

“We think this speaks to underlying worsening mental health and feelings of despair and social isolation as the drivers,” Yan said.

This dynamic is playing out in San Francisco, where 79% of accidental overdose deaths in 2022 were among men, according to city data.

Yan said it’s important to understand the reasons behind the growing disparity in life expectancy between men and women so that it can be reversed.

“Our research clearly demonstrates a gender dynamic in the way life expectancy is changing in the U.S.,” he said. “Understanding the ways gender plays a role in how people experience and seek preventive care and mental health care is important for us to develop interventions that help people get to better health.”