Maximal mid-expiratory flow detects early lung disease in α1-antitrypsin deficiency

Research output: Contribution to journalArticle


  • James Stockley
  • Asem M Ismail
  • Siân M Hughes
  • Ross Edgar
  • Robert A Stockley

External organisations

  • Dept of Lung Function and Sleep, University Hospital Birmingham, Birmingham, UK.
  • College of Medical and Dental Sciences, The University of Birmingham
  • Respiratory Medicine, University Hospital Birmingham, Birmingham, UK.
  • Institute of Inflammation and Ageing, Centre for Translational Inflammation Research, University of Birmingham, Birmingham, UK


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 FEV1 were 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) versus 9.67 (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.


Original languageEnglish
Article number1602055
JournalThe European respiratory journal
Issue number3
Publication statusPublished - 1 Mar 2017

ASJC Scopus subject areas