title: Lung function decline in relation to diagnostic criteria for airflow obstruction in respiratory symptomatic subjects.
abstract: BACKGROUND
  Current COPD guidelines advocate a fixed < 0.70 FEV1/FVC cutpoint to define airflow obstruction. We compared rate of lung function decline in respiratory symptomatic 40+ subjects who were 'obstructive' or 'non-obstructive' according to the fixed and/or age and gender specific lower limit of normal (LLN) FEV1/FVC cutpoints.
  
  
  METHODS
  We studied 3,324 respiratory symptomatic subjects referred to primary care diagnostic centres for spirometry. The cohort was subdivided into four categories based on presence or absence of obstruction according to the fixed and LLN FEV1/FVC cutpoints. Postbronchodilator FEV1 decline served as primary outcome to compare subjects between the respective categories.
  
  
  RESULTS
  918 subjects were obstructive according to the fixed FEV1/FVC cutpoint; 389 (42%) of them were non-obstructive according to the LLN cutpoint. In smokers, postbronchodilator FEV1 decline was 21 (SE 3) ml/year in those non-obstructive according to both cutpoints, 21 (7) ml/year in those obstructive according to the fixed but not according to the LLN cutpoint, and 50 (5) ml/year in those obstructive according to both cutpoints (p = 0.004).
  
  
  CONCLUSIONS
  This study showed that respiratory symptomatic 40+ smokers and non-smokers who show FEV1/FVC values below the fixed 0.70 cutpoint but above their age/gender specific LLN value did not show accelerated FEV1 decline, in contrast with those showing FEV1/FVC values below their LLN cutpoint.
authors.affiliation: Department of Primary and Community Care, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands.
authors.forename: Reinier P
authors.initials: RP
authors.lastname: Akkermans
authors.forename: Marvin A
authors.initials: MA
authors.lastname: Berrevoets
authors.forename: Ivo J
authors.initials: IJ
authors.lastname: Smeele
authors.forename: Annelies E
authors.initials: AE
authors.lastname: Lucas
authors.forename: Bart P
authors.initials: BP
authors.lastname: Thoonen
authors.forename: Joke G
authors.initials: JG
authors.lastname: Grootens-Stekelenburg
authors.forename: Yvonne F
authors.initials: YF
authors.lastname: Heijdra
authors.forename: Chris
authors.initials: C
authors.lastname: van Weel
authors.forename: Tjard R
authors.initials: TR
authors.lastname: Schermer
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000402:Airway Obstruction / Q000175:diagnosis* / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000008:administration & dosage; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D012016:Reference Values; D014797:Vital Capacity
chemical_list: D001993:Bronchodilator Agents