Background/Purpose: Deaths due to external causes are a leading contributor to premature mortality in the United States (U.S.), yet trends over time and how these differ by demographic characteristics remain poorly understood. This study examined national trends in premature mortality rates due to external causes (poisonings, firearms, all other injuries) from 1999 to 2020 by intent (homicide, suicide, unintentional), demographic characteristics, and county-level factors.

Methods: This serial cross-sectional study used U.S. national death certificate data obtained from the National Center for Health Statistics and included all external causes of deaths among individuals aged 20-64 years from January 1999 to December 2020. Trends in age-standardized mortality rates and average annual percent change (AAPC) in rates were estimated by intent, age, sex, and race and ethnicity for each external cause. Given the potentially large change in death rates due to the COVID-19 pandemic in 2020, rate ratios were estimated for comparison between years 2019 and 2020.

Results/Outcomes: From 1999 to 2020, death rates increased for poisoning (AAPC 7.2%; 95%CI 5.8, 8.5) and firearm deaths (AAPC 1.3% 95% CI 0.8, 1.7). Death rates for unintentional poisoning increased 9.2% annually (AAPC 9.2; 95% CI 7.6, 10.7). Death rates also increased for suicides by firearm (AAPC 0.9; 95% CI 0.4, 1.3) and all other injuries (AAPC 3.2; 95%CI 2.7, 3.7). All racial and ethnic groups experienced an increase in poisoning deaths. However, the most rapid rise was among American Indian and Alaska Native individuals (AAPC 9.2; 95%CI 7.5, 10.9). Additionally, age-adjusted mortality rates due to firearm and injury were higher in counties with greater poverty and rurality. From 2019 to 2020, premature mortality rates from external causes accelerated further, largely from increases in unintentional poisoning, and firearm and injury deaths due to homicide.

Conclusions: Premature deaths rates due to poisoning, firearm, and all other injuries have increased. These trends varied by county-level poverty and rurality and impacted people of all racial and ethnic groups; though, patterns varied by intent. Our results provide evidence that targeted public health interventions at the local- and national-levels are needed to counteract the rising trend in premature mortality due to external causes.