title: Identification of smokers susceptible to development of chronic airflow limitation: a 13-year follow-up.
abstract: BACKGROUND
  Cigarette smoking is the cardinal cause of COPD, but only a relatively small percentage of smokers have development of clinically overt disease.
  
  
  OBJECTIVE
  To identify high-risk subjects and to assess the prognostic significance of "small airways" tests.
  
  
  METHODS
  University teaching hospital.
  
  
  METHODS
  Fifty-six smokers and ex-smokers of mean age 62.5 years (SD, 2.7) with a smoking history of 40.6 (18.9) pack-years were studied at the end of a 13-year follow-up period.
  
  
  METHODS
  Questionnaire and lung function tests, including static and dynamic lung volumes, airway resistance, maximal expiratory flow rates, and small airways tests, such as nitrogen slope of the alveolar plateau (N2 slope) and closing volume.
  
  
  RESULTS
  Eighty-two percent of subjects with a normal FEV1/vital capacity (VC) ratio at the start of the study (half of them with abnormal results of small airways tests) still had a normal FEV1/VC ratio 13 years later. In the remainder, all but one had final FEV1/VC values >60%. About 80% of subjects with a decreased FEV1/VC at the start (subjects with airflow obstruction) reached at the end of study lower than predicted FEV1/VC values. Only about 10% of these subjects showed an accelerated loss of FEV1, reaching end FEV1/VC values of <45%. Initial N2 slope predicted about 80% of end FEV1 values.
  
  
  CONCLUSIONS
  Middle-aged smokers are at no evident risk of functional deterioration if their FEV1/VC ratio is normal. This is so even if results of small airways tests are abnormal. A decreased FEV1/VC ratio has no serious implications in itself. Only an associated high N2 slope adds the necessary information to predict a low FEV1. Present data suggest that a subgroup of smokers in their 50s, characterized by a low FEV1/VC ratio and a high N2 slope, are probably the susceptible smokers at high risk for development of COPD.
authors.affiliation: Pulmonary Laboratory and Division, Cliniques Universitaires Saint-Luc, Brussels, Belgium. Stanescu@pneu.ucl.ac.be
authors.forename: D
authors.initials: D
authors.lastname: Stănescu
authors.forename: A
authors.initials: A
authors.lastname: Sanna
authors.forename: C
authors.initials: C
authors.lastname: Veriter
authors.forename: A
authors.initials: A
authors.lastname: Robert
mesh_terms: D000402:Airway Obstruction / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008173:Lung Diseases, Obstructive / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D013147:Spirometry; D011795:Surveys and Questionnaires; D014797:Vital Capacity