Defining race/ethnicity and explaining difference in research studies on lung function.

The 2005 guidelines of the American Thoracic Society/European Respiratory Society recommend the use of race- and/or ethnic-specific reference standards for spirometry. Yet definitions of the key variables of race and ethnicity vary worldwide. The purpose of this study was to determine whether researchers defined race and/or ethnicity in studies of lung function and how they explained any observed differences. Using the methodology of the systematic review, we searched PubMed in July 2008 and screened 10 471 titles and abstracts to identify potentially eligible articles that compared "white" to "other racial and ethnic groups". Of the 226 eligible articles published between 1922 and 2008, race and/or ethnicity was defined in 17.3%, with the proportion increasing to 70% in the 2000s for those using parallel controls. Most articles (83.6%) reported that "other racial and ethnic groups" have a lower lung capacity compared to "white"; 94% of articles failed to examine socioeconomic status. In the 189 studies that reported lower lung function in "other racial and ethnic groups", 21.8% and 29.4% of explanations cited inherent factors and anthropometric differences, respectively, whereas 23.1% of explanations cited environmental and social factors. Even though researchers sought to determine differences in lung function by race/ethnicity, they typically failed to define their terms and frequently assumed inherent (or genetic) differences.