Residential segregation and lung cancer mortality in the United States.

OBJECTIVE: To examine the relationship between race and lung cancer mortality and the effect of residential segregation in the United States.
DESIGN: A retrospective, population-based study using data obtained from the 2009 Area Resource File and Surveillance, Epidemiology and End Results program.
SETTING: Each county in the United States. PATIENTS: Black and white populations per US county. MAIN OUTCOME MEASURES: A generalized linear model with a Poisson distribution and log link was used to examine the association between residential segregation and lung cancer mortality from 2003 to 2007 for black and white populations. Our primary independent variable was the racial index of dissimilarity. The index is a demographic measure that assesses the evenness with which whites and blacks are distributed across census tracts within each county. The score ranges from 0 to 100 in increasing degrees of residential segregation. RESULTS The overall lung cancer mortality rate was higher for blacks than whites (58.9% vs 52.4% per 100 000 population). Each additional level of segregation was associated with a 0.5% increase in lung cancer mortality for blacks (P < .001) and an associated decrease in mortality for whites (P = .002). Adjusted lung cancer mortality rates among blacks were 52.4% and 62.9% per 100 000 population in counties with the least (<40% segregation) and the highest levels of segregation (≥60% segregation), respectively. In contrast, the adjusted lung cancer mortality rates for whites decreased with increasing levels of segregation.
CONCLUSION: Lung cancer mortality is higher in blacks and highest in blacks living in the most segregated counties, regardless of socioeconomic status.