Open Journal of Respiratory Diseases, 2012, 2, 31-36 http://dx.doi.org/10.4236/ojrd.2012.22005 Published Online May 2012 (http://www.SciRP.org/journal/ojrd) Should We Measure the FEV 1 or the Specific Resistance of the Airways? An Evaluation in Patients with Either COPD, Chronic Dyspnea or Chronic Cough * Kinga Simon 1 , Viviane De Maertelaer 2 , André Noseda 1 1 The Pulmonary Division, CHU Brugmann, Brussels, Belgium 2 IRIBHN and Department of Biostatistics and Medical Informatics (SBIM), Université Libre de Bruxelles, Brussels, Belgium Email: andre.noseda@chu-brugmann.be Received December 27, 2011; revised February 3, 2012; accepted February 13, 2012 ABSTRACT Background: The purpose of this study was to evaluate the relative contribution of measuring the forced expiratory volume in one second (FEV 1 ) or the specific resistance of the airways (sRaw) in adults referred for chronic obstructive pulmonary disease (COPD), chronic dyspnea or chronic cough. Methods: This was a prospective study of 321 subjects referred for lung function testing, in a setting of routine clinical management, for suspicion of COPD (or follow-up of known COPD), chronic dyspnea or chronic cough. The proportions of FEV 1 values below the normal range and of sRaw values above the normal range were compared using a Chi-square exact test of Fisher. Results: In the COPD and chronic dyspnea groups, sRaw was as frequently abnormal as FEV 1 . In the chronic cough group, sRaw was increased in 56.5% of subjects, while FEV 1 was decreased in solely 34.8% (p = 0.059). Conclusions: This study suggests that sRaw may be a better tool than FEV 1 to detect bronchial obstruction in patients presenting with chronic cough. Keywords: Body Plethysmography; Chronic Cough; Specific Airway Resistance 1. Introduction Spirometry is often considered as the gold standard for determination of obstructive pulmonary disease. This method has however several limitations, which has led to resistance measurements used to clarify lung pathophysi- ology [1]. In the recent years, there has been a progres- sive disinterest in resistance measurements, at least in adults. As an illustration, the 2005 American Thoracic Society and European Respiratory Society statements did not address resistance measurements [2]. In contrast, resistance measurements are still considered to be par- ticularly relevant in pediatric patients [3,4]. The present study was designed to evaluate the relative contribution of measuring the forced expiratory volume in one second (FEV 1 ) or the specific resistance of the airways (sRaw) in adults referred for lung function test- ing (LFT) because of chronic obstructive pulmonary dis- ease (COPD), chronic dyspnea or chronic cough. These indications were chosen because the Belgian authorities recently suggested that the usefulness of assessing airway resistance is not proven in subjects with either COPD, chronic dyspnea or chronic cough [5]. We hypothesized that sRaw may be more sensitive than FEV 1 in detecting bronchial obstruction in these groups of patients. The study was performed in a setting of routine clinical man- agement and aimed to evaluate the percentage of subjects with an abnormal test, namely a decreased FEV 1 or an increased sRaw. 2. Patients and Methods 2.1. Study Design In the present study, we prospectively evaluated the sRaw and the FEV 1 in three groups of subjects (as defined un- derneath) in a setting of routine clinical management. The patients were referred by their physician for LFT because of either COPD (group 1), chronic dyspnea (group 2) or chronic cough (group 3). The study protocol was approved by the Ethics Committee of the CHU Brug- mann and each subject gave written informed consent to the analysis of his (her) lung function data. 2.2. Patients The study was performed at the Pulmonary Division of the CHU Brugmann between 26/10/2009 and 16/07/2010. All males and females between 18 and 70 years old, re- ferred for LFT because of COPD, chronic dyspnea or chronic cough, were eligible provided they gave in- formed consent and were able to perform technically * Conflict of interest: There is no conflict of interest. Copyright © 2012 SciRes. OJRD