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Claudio Sorino,1,2 Salvatore Battaglia,1 Nicola Scichilone,1 Claudio Pedone,3 Raffaele Antonelli-Incalzi,3 Duane Sherrill,4 Vincenzo Bellia11Biomedical Department of Internal and Specialist Medicine, Section of Pulmonology, University of Palermo, Italy; 2Division of Pulmonology, S Anna Hospital, Como, Italy; 3Chair of Geriatrics, University Campus Bio-Medico, Roma, Italy; 4Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson, AZ, USABackground: The choice between lower limit of normal or fixed value of forced expiratory volume in one second/forced vital capacity ratio (FEV1/FVC) < 0.70 as the criterion for confirming airway obstruction is an open issue. In this study, we compared the criteria of lower limit of normal and fixed FEV1/FVC for diagnosis of airway obstruction, with a focus on healthy elderly people.Methods: We selected 367 healthy nonsmoking subjects aged 65–93 years from 1971 participants in the population-based SARA (Salute Respiratoria nell’Anziano, Italian for “Respiratory Health in the Elderly”) study, analyzed their spirometric data, and tested the relationship between spirometric indices and anthropometric variables. The lower limit of normal for FEV1/FVC was calculated as the fifth percentile of the normal distribution for selected subjects.Results: While FEV1 and FVC decreased significantly with aging, the relationship between FEV1/FVC and age was not statistically significant in men or women. The lower limit of normal for FEV1/FVC was 0.65 in men and 0.67 in women. Fifty-five participants (15%) had FEV1/FVC < 0.70 and would have been inappropriately classified as obstructed according to the Global Initiative for Obstructive Lung Disease, American Thoracic Society/European Respiratory Society, and Canadian guidelines on chronic obstructive pulmonary disease. By applying different FEV1/FVC thresholds for the different age groups, as previously proposed in the literature, (0.70 for <70 years, 0.65 for 70–80 years, and 0.60 for >80 years) the percentage of patients classified as obstructed decreased to 6%. No subjects older than 80 years had an FEV1/FVC < 0.60.Conclusion: The present results confirm the inadequacy of FEV1/FVC < 0.70 as a diagnostic criterion for airway obstruction after the age of 65 years. FEV1/FVC < 0.65 and <0.67 (for men and women, respectively) could identify subjects with airway obstruction in such a population. Further reduction of the threshold after 80 years is not justified.Keywords: aging, airflow obstruction, chronic obstructive pulmonary disease, forced expiratory volume, lung function tests, spirometryA Letter to the Editor has been received and published for this article.