What Defines Copd In Asymptomatic Elderly Never-smokers, FEV₁/FVC<a Fixed Ratio Of70%or Lower Limit Of Normal?

Objectives:The aim of the study was to establish new spirometric reference equations for Jinan citizens and to compare the most accepted two spirometric definitions of Chronic Obstructive Pulmonary Disease (COPD)—post-bronchodilator forced expriratory volume in1second (FEV1)/forced vital capacity (FVC)<a fixed ratio of70%VS. FEV1/FVC<lower limit of normal (LLN)—in the elderly population (aged≥60yrs).Methods:Among10002cases, only never-smokers who had no respiratory symptoms or diagnosed cardiopulmonary diseases and whose lung function measurement strictly followed the American Thoracic Society (ATS) guidelines, were included in statistical analysis. For each sex, prediction equations of lung function (FEV1, FVC, FEV1/FVC) and corresponding LLN were developed using a multiple regression model, with age, height and weight as potential predictors.Results:In this cross-sectional study, spirometric reference values were statistically derived from a sample of1328healthy never-smokers (672men and656women), aged45-84yrs. As expected, age and height were the main predictors for lung function parameters. Using the two spirometric definitions, the number of pulmonary function test (PFT) results interpreted as obstructed varied markedly in the elderly population for both sexes (males:x2=19.59, P<0.01; females:x2=5.67,0.01<P<0.05). Predicted FEV1, FVC and FEV1/FVC values were also calculated from previously published prediction equations. Compared to the newly developed reference values, significant differences were found (P<0.05). Conclusions:The Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria which defines FEV1/FVC<70%as airflow limitation will probably lead to over-diagnosis in asymptomatic elderly never-smokers. Our study suggests that use of LLN reduce the risk of misclassification in this case. However, cohort studies are urgently needed for clinical validation.