Sensitivity And Specificity of FEF25–75/Forced Vital Capacity for Diagnosing Restrictive Lung Disease

Abstract

Introduction and objective: The role of spirometry in the diagnosis of restrictive lung diseases is unclear. This study investigated the sensitivity and specificity of the forced expiratory flow 25–75 (FEF25–75)/forced vital capacity (FVC) parameter in diagnosing restrictive lung disease. Methods: In this study, the records of all restrictive patients who were referred to the pulmonary centre of Imam Khomeini Hospital, Tehran, Iran, from March 2021–March 2022 have been reviewed, and the indexes in the body box and spirometry have been recorded. Results: A total of 527 people were included in the study. Among them, 134 people (25.4%) had restrictive lung disease. The average area under the graph of the FEF25–75/FVC index is 0.648±0.028. It can be said that the area under the graph for the FEF25–75/FVC index is between 0.594–0.703. The FEF25–75/FVC index at values above 79.90 has a sensitivity of 70.9% and a false positive rate (1- specificity) of 53.2%. Conclusions: According to the result of this study, the ratio of FEF25–75/FVC index in spirometry at above 79.90 has a sensitivity of 70.9% and a false positive rate (1- specificity) of 53.2%. Therefore, it can be used as a screening test for restrictive lung diseases.