Severity of Airflow Obstruction Based on FEV₁/FVC Versus FEV₁ Percent Predicted in the General U.S. Population.

Abstract

<b>Rationale:</b> According to the Global Initiative for Obstructive Lung Disease (GOLD), the FEV₁/FVC ratio is used to confirm the presence of airflow obstruction in the diagnosis of chronic obstructive pulmonary disease (COPD), whereas FEV₁ percent predicted normal value (FEV₁%pred) is used for grading its severity. The STaging of Airflow obstruction by the FEV₁/FVC Ratio (STAR), and its prediction of adverse outcomes, has not been evaluated in general populations. <b>Objectives:</b> To compare the STAR (FEV₁/FVC) and the GOLD (FEV₁%pred) classifications for the severity of airflow limitation in terms of exertional breathlessness and mortality in the general U.S. population. <b>Methods:</b> Severity stages according to the STAR and GOLD were applied to the multiethnic National Health and Nutrition Examination Survey of 2007-2012, including people ages 18-80 years, using a postbronchodilatory FEV₁/FVC ratio of <0.70 to define airflow obstruction in both staging systems. Prevalence of the severity stages STAR 1-4 and GOLD 1-4 was calculated, and associations with breathlessness and mortality were analyzed by multinomial logistic regression and Cox regression, respectively. <b>Measurements and Main Results:</b> STAR versus GOLD severity staging of airflow obstruction showed similar associations with breathlessness and all-cause mortality, regardless of ethnicity and/or race. In those with airflow obstruction, the correlation between the two classification systems was 0.461 (<i>P</i> < 0.001). STAR reclassified 59% of GOLD 2 subjects as having mild airflow obstruction (STAR 1). Compared with GOLD 1, STAR 1 was more clearly differentiated from nonobstruction in terms of both breathlessness and mortality. <b>Conclusions:</b> FEV₁/FVC and FEV₁%pred as measures of airflow limitation severity show similar predictions of breathlessness and mortality in the adult U.S. population across ethnicity groups. However, Stage 1 differed more clearly from nonobstruction on the basis of FEV₁/FVC ratio than FEV₁%pred.