Association of Residential Racial and Ethnic Segregation With Legal Intervention Injuries in California.

Importance: The continued harm of Black individuals in the US by law enforcement officers calls for reform of both law enforcement officers and structural racism embedded in communities.

Objective: To examine the association between county characteristics and racial and ethnic disparities in legal intervention injuries.

Design, Setting, And Participants: This retrospective, cross-sectional study was conducted among 27 671 patients presenting to California hospitals from January 1, 2016, to December 31, 2019, with legal intervention injuries (defined as any injury sustained as a result of an encounter with any law enforcement officer) as identified by International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes.

Main Outcomes And Measures: Legal intervention injuries were classified by International Statistical Classification of Diseases and Related Health Problems, Tenth Revision external cause of injury code Y35. Expected injury counts were calculated for each county by multiplying statewide median rates of injury per capita for each age-racial and ethnic group, and then observed to expected injury ratios were measured. The association between county injury ratio, percentage of Black individuals, and residential segregation (measured using an index of dissimilarity) was modeled, stratifying by race and ethnicity.

Results: A total of 27 671 patients (24 159 male patients [87.3%]; 1734 Asian and Pacific Islander [6.3%], 5049 Black [18.2%], 11 250 Hispanic [40.7%], and 9638 White [34.8%]; mean [SD] age, 34.2 [12.5] years) presented with legal intervention injuries in California from 2016 to 2019. Observed to expected injury ratios ranged from 0 to 7 for Black residents and from 0 to 5 for White residents. High observed to expected injury ratios for Black residents (408 observed vs 60 expected; ratio = 7) were clustered around San Francisco Bay Area counties and corresponded with a higher proportion of Black residents. High observed to expected injury ratios for White residents (57 observed vs 11 expected; ratio = 5) clustered around rural northern California counties and corresponded with higher mean percentage of residents with income below the federal poverty level and fewer urban areas.

Conclusions And Relevance: This study suggests that residential segregation may be associated with increased legal intervention injury rates for Black residents of California counties with a large percentage of Black residents. Reform efforts to address racial and ethnic disparities in these injuries should carefully consider and address the legacy of discriminatory policies that has led to segregated communities in California and the United States.