FEV1/FEV6 to Diagnose Airflow Obstruction. Comparisons with Computed Tomography and Morbidity Indices

Abstract Rationale FVC is a difficult maneuver for many patients, and forced expiratory volume in 6 seconds (FEV6) has been proposed as a surrogate for FVC for the diagnosis of chronic obstructive pulmonary disease (COPD). Previous studies have performed head-to-head comparisons of these thresholds but did not examine their relationships with structural lung disease, symptoms, or exacerbations. Objectives To compare FEV1/FEV6 with FEV1/FVC in the diagnosis of COPD-related morbidity and structural lung disease as assessed by CT. Methods We analyzed data from a large multicenter cohort study (COPDGene) that included current and former smokers (age 45–80 yr). Accuracy and concordance between the two ratios in diagnosing structural COPD was compared using CT measures of emphysema and airway disease and COPD-related morbidity to assess how the two ratios compare in defining disease. Results A total of 10,018 subjects were included. FEV1/FEV6 showed excellent accuracy in diagnosing airflow obstruction using FEV1/FVC Conclusions FEV1/FEV6 can be substituted for FEV1/FVC in diagnosing airflow obstruction and may better predict COPD-related pathology and morbidity.