The effectiveness of lower limit of normal criteria and cutoff rate of forced expiratory volume in 1 s/forced expiratory volume in 6 s using in the diagnosis of airway obstruction in chronic obstructive pulmonary disease patients diagnosed with fixed ratio

Abstract

AIMS: The definition of limited airflow as forced expiratory volume in 1 s (FEV1)/forced vitalcapacity (FVC) ratio for chronic obstructive pulmonary disease (COPD) is still controversial. Theobjective of this study was to compare the prevalence of COPD using fixed ratio and lower limit ofnormal (LLN) of FEV1/FVC for the presence of airflow limitation and evaluate the performance ofFEV1/forced expiratory volume in 6 s (FEV6) in patients diagnosed with COPD according to the GlobalInitiative for Chronic Obstructive Lung Disease (GOLD) fixed ratio.SUBJECTS AND METHODS: Patients who presented to the pulmonary disease clinic between May2008 and December 2017 and who were diagnosed with COPD were evaluated retrospectively. Thedistribution of FEV1/FVC‑LLN according to the GOLD fixed ratio was evaluated after the patients weredivided based on age groups. A receiver operating characteristics curve was used to determine the bestFEV1/FEV6 cutoff value which fit into the FEV1/FVC LLN. The cutoff value of FEV1/FEV6for airway obstruction according to FEV1/FVC