title: Maximal mid-expiratory flow detects early lung disease in α1-antitrypsin deficiency.
abstract: Pathological studies suggest that loss of small airways precedes airflow obstruction and emphysema in chronic obstructive pulmonary disease (COPD). Not all α1-antitrypsin deficiency (AATD) patients develop COPD, and measures of small airways function might be able to detect those at risk.Maximal mid-expiratory flow (MMEF), forced expiratory volume in 1 s (FEV1), ratio of FEV1/forced vital capacity (FVC), health status, presence of emphysema (computed tomography (CT) densitometry) and subsequent decline in FEV1were assessed in 196 AATD patients.FEV1/FVC, FEV1% predicted and lung densitometry related to MMEF % pred (r2=0.778, p<0.0001; r2=0.787, p<0.0001; r2=0.594, p<0.0001, respectively) in a curvilinear fashion. Patients could be divided into those with normal FEV1/FVC and MMEF (group 1), normal FEV1/FVC and reduced MMEF (group 2) and those with spirometrically defined COPD (group 3). Patients in group 2 had worse health status than group 1 (median total St George's Respiratory Questionnaire (SGRQ) 23.15 (interquartile range (IQR) 7.09-39.63)versus9.67 (IQR 1.83-22.35); p=0.006) and had a greater subsequent decline in FEV1(median change in FEV1-1.09% pred per year (IQR -1.91-0.04% pred per year)versus-0.04% pred per year (IQR -0.67-0.03% pred per year); p=0.007).A reduction in MMEF is an early feature of lung disease in AATD and is associated with impaired health status and a faster decline in FEV1.
authors.affiliation: Dept of Lung Function and Sleep, University Hospital Birmingham, Birmingham, UK.
authors.forename: James A
authors.initials: JA
authors.lastname: Stockley
authors.affiliation: College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Asem M
authors.initials: AM
authors.lastname: Ismail
authors.affiliation: Dept of Lung Function and Sleep, University Hospital Birmingham, Birmingham, UK.
authors.forename: Siân M
authors.initials: SM
authors.lastname: Hughes
authors.affiliation: Dept of Lung Function and Sleep, University Hospital Birmingham, Birmingham, UK.
authors.forename: Ross
authors.initials: R
authors.lastname: Edgar
authors.affiliation: Respiratory Medicine, University Hospital Birmingham, Birmingham, UK.|Joint senior authors.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Stockley
authors.affiliation: Institute of Inflammation and Ageing, Centre for Translational Inflammation Research, University of Birmingham, Birmingham, UK e.sapey@bham.ac.uk.|Joint senior authors.
authors.forename: Elizabeth
authors.identifier: 0000-0003-3454-5482
authors.initials: E
authors.lastname: Sapey
mesh_terms: D000328:Adult; D005260:Female; D005541:Forced Expiratory Volume; D006304:Health Status; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology*; D011656:Pulmonary Emphysema / Q000175:diagnosis / Q000503:physiopathology*; D012042:Registries; D012907:Smoking / Q000503:physiopathology; D013147:Spirometry; D014057:Tomography, X-Ray Computed; D006113:United Kingdom; D014797:Vital Capacity; D019896:alpha 1-Antitrypsin Deficiency / Q000150:complications* / Q000503:physiopathology*