California mortality and the Healthy Places Index.

We investigated California mortality and social determinants of health, as measured by the Healthy Places Index (HPI), which is a composite measure of 23 indicators of neighborhood (census tract) economic conditions, education, transportation, housing, social capital, environmental pollution, built environment, and access to health care. We aggregated deaths to 2010 census tract boundaries for leading causes during 2015 to 2019, and for COVID-19 during 2020-2021, from death certificates, and populations from the American Community Survey, 2015 to 2019. We age-adjusted and stratified death rates by HPI deciles, age, sex, and race/ethnicity, and examined HPI dose-response with segmental regression. For all causes, cancer, cardiovascular disease, COVID-19, diabetes, cirrhosis of the liver, injuries, and Alzheimer's disease (ages 65-74 years), mortality rates were inversely related to HPI decile. For all-cause mortality, the rate ratio between the 1st and 10th deciles (reference) was 1.63 (95% CI, 1.60-1.66); for COVID-19, the rate ratio was 7.61 (95% CI, 7.14-8.12). The population attributable fraction was 24% for all causes and 72% for COVID-19. Age, sex, and race/ethnicity modified the steepness and shape of dose-response curves. The findings illustrate opportunities to incorporate area-based socioeconomic measures in routine public health surveillance and to reinforce policies and programs that reduce health inequities.