title: Understanding socioeconomic and racial differences in adult lung function.
abstract: BACKGROUND
  The contribution of socioeconomic factors to racial differences in the distribution of lung function is not well understood.
  
  
  OBJECTIVE
  We investigated the contribution of socioeconomic factors to racial differences in FEV₁ using statistical tools that allow for examination across the population distribution of FEV₁.
  
  
  METHODS
  We compared FEV₁ 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.
  
  
  RESULTS
  In the entire sample with acceptable spirometry (n ¼ 9,658), high school completion was associated with a mean 69.13-ml increase in FEV₁ for males (P , 0.05) and a mean 50.75-ml increase in FEV₁ for females (P , 0.01). In quantile regression analysis, we observed a significant racial difference in the association of high school completion with FEV₁ among both sexes that varied across the distribution; college completion was associated with an additional increase in FEV₁ 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 ¼ 2,638), the association with high school completion was not significant.
  
  
  CONCLUSIONS
  High school completion is associated with racially patterned improvements in the FEV₁ of adults in the general population. The application of routine exclusion criteria leads to underestimates of the role of high school completion on FEV₁.
authors.affiliation: Department of Population Health Sciences, University of Wisconsin–Madison, Madison, Wisconsin 53726, USA. vansickle@wisc.edu
authors.forename: David
authors.initials: D
authors.lastname: Van Sickle
authors.forename: Sheryl
authors.initials: S
authors.lastname: Magzamen
authors.forename: John
authors.initials: J
authors.lastname: Mullahy
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D044383:Black People; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012959:Socioeconomic Factors; D013147:Spirometry; D014481:United States; D014797:Vital Capacity / Q000502:physiology*; D044465:White People; D055815:Young Adult; D001741:Black or African American