Socioeconomic inequalities in premature cancer mortality among U.S. Counties during 1999 to 2018

Abstract

Background: This study investigated socioeconomic inequalities in premature cancer mortality by cancer types, and evaluated the associations between socioeconomic status (SES) and premature cancer mortality by cancer types. Methods: Using multiple databases, cancer mortality was linked to SES and other county characteristics. The outcome measure was cancer mortality among adults ages 25-64 years in 3,028 U.S. counties, from 1999 to 2018. Socioeconomic inequalities in mortality were calculated as a concentration index (CI) by income (annual median household income), educational attainment (% with bachelor's degree or higher), and unemployment rate. A hierarchical linear mixed model and dominance analyses were used to investigate SES associated with county-level mortality. The analyses were also conducted by cancer types. Results: CIs of SES factors varied by cancer types. Low-SES counties showed increasing trends in mortality, while high-SES counties showed decreasing trends. Socioeconomic inequalities in mortality among high-SES counties were larger than those among low-SES counties. SES explained 25.73% of the mortality. Countylevel cancer mortality was associated with income, educational attainment, and unemployment rate, at -0.24 [95% (CI): -0.36 to-0.12],-0.68 (95% CI:-0.87 to-0.50), and 1.50 (95% CI: 0.92- 2.07) deaths per 100,000 population with one-unit SES factors increase, respectively, after controlling for health care environment and population health. Conclusions: SES acts as a key driver of premature cancer mortality, and socioeconomic inequalities differ by cancer types.