Socioeconomic Differences in the Epidemiologic Transition From Heart Disease to Cancer as the Leading Cause of Death in the United States, 2003 to 2015 An Observational Study

Background: Recent data suggest that the United States is in the midst of an epidemiologic transition in the leading cause of death. Objective: To examine county-level sociodemographic differences in the transition from heart disease to cancer as the leading cause of death in the United States. Design: Observational study. Setting: U.S. death records, 2003 to 2015. Participants: Decedents aged 25 years or older, classified by racial/ethnic group. Measurements: All-cause, heart disease, and cancer mortality stratified by quintiles of county median household income. Age- and sex-adjusted mortality rates and average annual percentage of change were calculated. Results: Heart disease was the leading cause of death in 79% of counties in 2003 and 59% in 2015. Cancer was the leading cause of death in 21% of counties in 2003 and 41% in 2015. The shift to cancer as the leading cause of death was greatest in the highest-income counties. Overall, heart disease mortality rates decreased by 28% (30% in high-income counties vs. 22% in low-income counties) from 2003 to 2015, and cancer mortality rates decreased by 16% (18% in high-income counties vs. 11% in low-income counties). In the lowest-income counties, heart disease remained the leading cause of death among all racial/ethnic groups, and improvements were smaller for both heart disease and cancer. Limitation: Use of county median household income as a proxy for socioeconomic status. Conclusion: Data show that heart disease is more likely to be the leading cause of death in low-income counties. Low-income counties have not experienced the same decrease in mortality rates as high-income counties, which suggests a later transition to cancer as the leading cause of death in low-income counties.