We also found no evidence of a higher risk of COPD among African-Americans in contrast to a case-control study of 70 cases of early-onset COPD,8 a retrospective review of 160 patients presenting for lung volume reduction surgery,9 and a prospective study of 50 African-Americans and 278 Caucasians,10 all using self-reported race/ethnicity. One explanation for these differences is that prior findings in early-onset and very severe COPD may not apply to the general population and, conversely, findings in the general population may not apply to these extreme phenotypes. Notably, a more recent study incorporating genetic measures by Aldrich et al11 used AIMs and identified a trend, though non-significant, toward an interaction between African ancestry and smoking on FEV1 in cross-sectional and longitudinal analysis among self-reported African-Americans. These findings were not replicated in our present study. Differences include an older cohort with a higher mean pack-years (30) among the participants in the study by Aldrich et al as well as the longitudinal approach, suggesting that it could be possible that there is more variability by race as individuals age.