Race and neighbourhood social determinants of homicide and suicide, California (2015–2021)

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Background We investigated social determinants of homicide and suicide and effect modification by race/ethnicity, age and sex before and during the COVID-19 pandemic in California. Methods and results The Healthy Places Index (HPI) combines 23 indicators of neighbourhood economic conditions, education, transportation, housing, social capital, environmental pollution, built environment and access to healthcare. We aggregated 15 346 homicides and 30 087 suicides to 2010 census tracts from death certificates and populations from the American Community Survey (2015–2019), and the 2020 decennial census. We linked deaths and populations to census tract HPI scores. We age-adjusted and stratified death rates by HPI deciles, age, sex, race/ethnicity and time period (2015–2019 and 2020–2021) and examined HPI dose-response with segmental regression. Homicide rates were inversely associated with HPI deciles prior to and during the COVID-19 pandemic. The rate ratio between the 1 st and 10 th HPI decile (RR d1/D10 ) was 10.4 (CI 95% : 7.47–17.7) in 2015–2019 and 14.5 (CI 95% : 10.4–20.8) in 2020–2021. The prepandemic population attributable percent of HPI-associated homicide was 78%. Suicide rates in 2015–2019 were inversely associated with HPI scores in Asian (RR d1/D10 : 2.57 (1.44–4.47)) and non-Hispanic White (RR d1/D10 : 2.12 (1.68–2.66)) individuals, but positively associated (9.6% per HPI decile) in Hispanic women. The prepandemic associations between the HPI and suicide or homicide persisted in 2020–2021. Conclusions A substantial burden of intentional injury mortality existed prior to the pandemic. Area-based socioeconomic measures can be integrated into injury surveillance to guide prioritisation and targeting policies and programmes that reduce health inequities.