title: Defining obstructive ventilatory defect in 2015.
abstract: There is no clear consensus as to what constitutes an obstructive ventilatory defect (OVD): Is it FEV1/FVC<lower limit of normal (LLN) or<0.70 (respectively, physiological and operational definitions)?
  
  
  
  To determine, according to the two definitions, the percentage of subjects having an OVD among them explored in a lung function exploration laboratory.
  
  
  
  This is a retrospective study including 4,730 subjects aged 17-85 years. Subjects were divided according to the presence [physio (+) or operat (+)] or absence [physio (-) or operat (-)] of an OVD, and into younger (<45 years, n=2,076), older (≥45 years, n=2,654), smokers (n=1,208), and non-smokers (n=3,522) groups.
  
  
  
  For the total sample, the younger and older groups [mean±SD of age (years), respectively, 46.7±14.1; 33.9±7.4, and 56.8±9.1], the 'physiological definition' detected, respectively, 13.46, 43.22, and 5.09% more OVD than the 'operational one' (p<0.05). In addition, the operational definition, compared with the physiological one, overdiagnosed OVD in 2.33 and 0.44% of smokers and non-smokers, respectively, and underdiagnosed it in 4.46% and 29.72% of smokers and non-smokers, respectively (p<0.05). Compared with the group 'physio (-), operat (+)', the 'physio (+), operat (-)' one was younger (74.2±4.7 years vs. 40.9±10.3 years) and had significantly higher FEV1 (62±13% vs. 78±17%) and FVC (71±15% vs. 93±19%).
  
  
  
  The frequency of OVD much depends on the criteria used for its definition.
authors.affiliation: Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia.
authors.forename: Zied
authors.initials: Z
authors.lastname: Affes
authors.affiliation: Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia.
authors.forename: Salaheddine
authors.initials: S
authors.lastname: Rekik
authors.affiliation: Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia.|Laboratory of Physiology, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia.|Research Laboratory N° LR14ES05: Interactions of the Cardiopulmonary System, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia; helmi.bensaad@rns.tn.
authors.forename: Helmi
authors.initials: H
authors.lastname: Ben Saad
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects / Q000503:physiopathology; D013147:Spirometry / Q000379:methods; D014416:Tunisia / Q000453:epidemiology; D014797:Vital Capacity
keywords: FEV1/FVC; fixed threshold; guideline; lower limit of normal; obstructive ventilatory defect; spirometry