Identifying the Changing Landscape of Younger Adult Mortality in the United States from 1999 to 2021.

PURPOSE: To evaluate temporal trends and drivers of mortality among younger adults (aged 18-39), from 1999 to 2021.

METHODS

Observational study using nationally representative United States mortality data from 1999 to 2021, acquired via the US Centers for Disease Control Wide-ranging Online Data for Epidemiologic Research database. Exposure of interest was cause of death. Primary outcomes were population-level mortality rates and percent increase from 1999 to 2021. Secondary outcomes were cause-specific and subgroup-specific (sex, race, ethnicity) mortality rates and percent increases.

RESULTS

From 1999 to 2021, US younger adults aged 18-39 experienced a 54.1% increase in annual mortality (from 113.4 deaths per 100,000 in 1999 to 174.7 deaths per 100,000 in 2021; Cochran-Armitage p < .0001). Before COVID, from 1999 to 2019, younger adults experienced a 10.8% increase in mortality, compared to a 1.5% increase among the broader US population. The top driver of increased younger adult mortality, from 1999 through 2021, was accidental poisoning and exposure to noxious substances. Mortality trends varied by demographic variables with notable increases among American Indian/Alaskan Native Americans.

DISCUSSION: US younger adults are suffering from rising premature mortality. Resources should be calibrated to better support this generation.