In their cross-sectional study, Powell et al 1 found no evidence that genetic ancestry or self-reported ethnicity effected lung function among US smokers, in particular no evidence of a reduced risk of COPD in Hispanics (Hispanic paradox) previously described in a prospective study by Bruse et al.2 This observation might be due, in part, to the definition of Hispanic and lighter smoking histories in the Powell study.

In the Powell study, only 51% of those defined as Hispanic were Mexican while the rest were predominantly of Caribbean ancestry. This is important because the Mexican Hispanics are of European and American Indian ancestry, whereas the Caribbean …