title: Fixed ratio or lower limit of normal for the FEV1/VC ratio: relation to symptoms and extended lung function tests.
abstract: There is no general agreement on the spirometric definition of chronic obstructive pulmonary disease (COPD). The global initiative for obstructive lung disease recommends a fixed ratio between forced expiratory volume in one-second (FEV1) and forced vital capacity (FVC) of <0·7 (FR) for the diagnosis of COPD. European Respiratory Society and American Thoracic Society favour the use of the fifth percentile of the age-related FEV1/FVC ratio (the lower limit of normal, LLN). The purpose of this study was to analyse extensive lung function tests in groups of subjects fulfilling none, either or both of the spirometric criteria for COPD. From a previous population-based study, 450 subjects were examined with spirometry, body pletysmography diffusing capacity for CO (DL,CO), Impulse Oscillometry System (IOS) and answered a questionnaire on respiratory symptoms and diseases. Seventy subjects fulfilled both spirometric COPD criteria (FR+LLN+), 62 subjects the fixed ratio criterion (FR+) only. Of the remaining 318 subjects, 236 were ever smokers (N-ES). Significant differences between all groups were seen for FEV1and DL,CO. Significant differences between groups were also seen for residual volume (RV) and RV/total lung capacity. For IOS, variables and symptoms increasingly abnormal values were seen from never smokers to FR+LLN+. This study shows that subjects meeting both spirometric COPD criteria frequently have symptoms and findings at extended lung function tests compatible with the diagnosis. Also subjects meeting the fixed ratio criterion only tend to have more symptoms and lung function findings compatible with COPD than ever-smoking subjects with FEV1/VC > 0·7.
authors.affiliation: Department of Translational Medicine, Clinical Physiology and Nuclear Medicine, Lund University, Malmö, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Wollmer
authors.affiliation: Department of Translational Medicine, Clinical Physiology and Nuclear Medicine, Lund University, Malmö, Sweden.
authors.forename: Sophia
authors.initials: S
authors.lastname: Frantz
authors.affiliation: Department of Clinical Sciences, Cardio-vascular Epidemiology, Lund University, Malmö, Sweden.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Engström
authors.affiliation: Department of Translational Medicine, Clinical Physiology and Nuclear Medicine, Lund University, Malmö, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Dencker
authors.affiliation: Department of Clinical Sciences, Respiratory Medicine and Allergology, Lund University, Lund, Sweden.
authors.forename: Claes-Göran
authors.initials: CG
authors.lastname: Löfdahl
authors.affiliation: Department of Clinical Sciences, Respiratory Medicine and Allergology, Lund University, Lund, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Nihlén
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009991:Oscillometry; D010993:Plethysmography, Whole Body; D011237:Predictive Value of Tests; D011379:Prognosis; D011653:Pulmonary Diffusing Capacity; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D012016:Reference Values; D012907:Smoking / Q000009:adverse effects / Q000503:physiopathology; D013147:Spirometry / Q000379:methods*; D011795:Surveys and Questionnaires; D014797:Vital Capacity
keywords: Impulse Oscillometry System; chronic obstructive pulmonary disease; diagnosis; diffusing capacity for CO; spirometry