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, 2015 to 2019, and COVID-19, 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, gender, 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 causes mortality, the rate ratio between the 1st and 10th decile (reference) was 1.63 (CI95%: 1.60-1.66), and, for COVID-19, the rate ratio was 7.61 (CI95%: 7.14-8.12). The population attributable fraction was 24% for all causes and 72% for COVID-19. Age, gender, 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.