Understanding Socioeconomic and Racial Differences in Adult Lung Function

Rationale: The contribution of socioeconomic factors to racial differences in the distribution of lung function is not well understood. Objectives: We investigated the contribution of socioeconomic factors to racial differences in FEV(1) using statistical tools that allow for examination across the population distribution of FEV(1). Methods: We compared FEV(1) for white and African-American participants (aged 20-80 yr) in NHANES III with greater than or equal to two acceptable maneuvers to a restricted sample following the routine exclusion criteria used to derive population reference equations. Ordinary least squares and quantile regression analyses using spirometric, anthropometric, and socioeconomic data (high school completion) were performed separately by sex for both data sets. Measurements and Main Results: In the entire sample with acceptable spirometry (n = 9,658), high school completion was associated with a mean 69.13-ml increase in FEV(1) for males (P < 0.05) and a mean 50.75-ml increase in FEV(1) for females (P < 0.01). In quantile regression analysis, we observed a significant racial difference in the association of high school completion with FEV(1) among both sexes that varied across the distribution; college completion was associated with an additional increase in FEV(1) for white males (70.36-250.76 ml) and white females (57.87-317.77 ml). Routine exclusion criteria differentially excluded individuals by age, race, and education. In the restricted sample (n = 2,638), the association with high school completion was not significant. Conclusions: High school completion is associated with racially patterned improvements in the FEV(1) of adults in the general population. The application of routine exclusion criteria leads to underestimates of the role of high school completion on FEV(1).