Severity of Airflow Obstruction Based on FEV1/FVC vs FEV1% of Predicted in the General US Population.

Abstract

According to GOLD, the ratio of FEV1/FVC is used to confirm airflow obstruction in COPD diagnosis, whereas FEV1% of predicted (FEV1%pred) is used for severity grading. STaging of Airflow obstruction by the FEV1/FVC Ratio (STAR) and its prediction of adverse outcomes has not been evaluated in general populations. To compare the STAR (FEV1/FVC) versus GOLD (FEV1%pred) classification for the severity of airflow limitation in terms of exertional breathlessness and mortality in the general US population. Severity stages according to STAR and GOLD were applied to the multi-ethnic National Health and Nutrition Examination Survey (NHANES) 2007-2012 survey including ages 18-80 years, using post-bronchodilatory FEV1/FVC<0.70 to define airflow obstruction in both staging systems. Prevalence of 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. STAR versus GOLD severity staging of airflow obstruction showed similar associations with breathlessness and all-cause mortality, regardless of ethnicity/race. In those with airflow obstruction, the correlation between the two classification systems was 0.461 (p<0.001). STAR reclassified 59% of GOLD stage 2 as having mild airflow obstruction (STAR 1). STAR 1 was more clearly differentiated from the non-obstructive compared to GOLD stage 1 in terms of both breathlessness and mortality. FEV1/FVC and FEV1%pred as measures of severity of airflow limitation show similar prediction of breathlessness and mortality in the adult US population across ethnicity groups. However, stage 1 differed more clearly from non-obstructive based on FEV1/FVC than FEV1%pred. This article is open access and distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).