title: Risk factors associated with the presence of irreversible airflow limitation and reduced transfer coefficient in patients with asthma after 26 years of follow up.
abstract: BACKGROUND
  Childhood asthma is generally believed to be a disorder with a good prognosis. However, some asthmatics develop irreversible airway obstruction, probably as a result of airway remodelling.
  
  
  METHODS
  After 21-33 years, 228 adults (aged 13-44 years at baseline) with a history of asthma were re-examined to assess risk factors for the development of irreversible airway obstruction (IAO, forced expiratory volume in 1 second (FEV(1)) <80% predicted and reversibility <9% predicted) and a reduced postbronchodilator transfer coefficient (carbon monoxide transfer factor/alveolar volume, <80% predicted), both characteristics of COPD.
  
  
  RESULTS
  At follow up, 41% did not have airway obstruction (NAO), 43% had reversible airway obstruction (RAO), and 16% had IAO; 23% had a reduced transfer coefficient. Patients with RAO had asthma-like characteristics (wheezing, asthma attacks, bronchial hyperresponsiveness (BHR)) while patients with IAO had COPD-like symptoms (cough, phlegm, dyspnoea) at follow up. The development of IAO is determined by a lower FEV(1), less reversibility of airway obstruction and, surprisingly, less severe BHR at initial screening. Eighty percent of the patients with asthma who used anti-inflammatory medication still had airway obstruction, but IAO developed less frequently. Smoking was associated with a reduced transfer coefficient but not with the development of IAO. Female sex was associated with a reduced transfer coefficient, whereas corticosteroid use was not.
  
  
  CONCLUSIONS
  Although IAO and a low transfer coefficient are both characteristics of COPD, they represent distinct entities in adult asthmatics in terms of symptomatology, aetiology, and probably in therapeutic approaches and disease prevention.
authors.affiliation: Department of Epidemiology and Statistics, University of Groningen, The Netherlands.
authors.forename: J M
authors.initials: JM
authors.lastname: Vonk
authors.forename: H
authors.initials: H
authors.lastname: Jongepier
authors.forename: C I M
authors.initials: CI
authors.lastname: Panhuysen
authors.forename: J P
authors.initials: JP
authors.lastname: Schouten
authors.forename: E R
authors.initials: ER
authors.lastname: Bleecker
authors.forename: D S
authors.initials: DS
authors.lastname: Postma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000209:etiology* / Q000503:physiopathology; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000627:therapeutic use; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000209:etiology / Q000503:physiopathology; D012307:Risk Factors
chemical_list: D001993:Bronchodilator Agents