Social Determinants of Health and Racial Disparities in Lung Function: Findings from the National Health and Nutrition Examination Survey, 2007–2012

<b>Rationale:</b> We hypothesized that the disproportionate impact of social determinants of health (SDoH) captured in survey data could help explain a larger proportion of racial gaps in lung function than previously reported. <b>Objective:</b> To estimate the contribution of SDoH to racial gaps in lung function. <b>Methods:</b> We defined a series of nested, increasingly healthy reference populations using data from the National Health and Nutrition Examination Survey, 2007-2012. Starting with nonsmokers without respiratory symptoms or diagnoses, we sequentially excluded those with confirmed occupational exposure to dust and/or fumes, physical inactivity, maternal or secondhand tobacco use, obesity, no home ownership, no insurance, lower education, and self-reported unhealthy diet. Across successive populations, we compared average age-, sex-, and height-adjusted differences in FEV₁ and FVC between racial and ethnic minority groups and non-Hispanic White participants for adults (aged ⩾20 yr) and children (aged 6-19 yr). <b>Measurements and Main Results:</b> In successively healthier reference populations, the proportion of represented participants declined for non-Hispanic Black, Mexican American, and other Hispanic participants; increased for non-Hispanic White participants; and remained stable for non-Hispanic Asian participants. At baseline, adjusted FEV₁ and FVC were similar for Mexican American and non-Hispanic White American participants but lower for other racial and ethnic minority groups. After excluding individuals with unfavorable SDoH, racial disparities in FEV₁ and FVC decreased for non-Hispanic Black children (24.8% and 26.2%) and adults (26.3% and 19.4%), other Hispanic children (15.2% and 19.3%) and adults (85.9% and 12.4%), and non-Hispanic Asian children (6.6% and 12.5%), but they increased for non-Hispanic Asian adults (14.1% and 11.1%). <b>Conclusions:</b> Unfavorable SDoH disproportionately affected non-Hispanic Black, Mexican American, and other Hispanic populations and explained a higher proportion of racial disparities in lung function than previously reported.