title: Asthma masquerading as chronic obstructive pulmonary disease: a study of smokers fulfilling the GOLD definition of chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Irreversible airways obstruction in smokers is usually attributed to chronic obstructive pulmonary disease (COPD). We speculate that some of these are cases of asthma indistinguishable from COPD.
  
  
  OBJECTIVE
  To determine the prevalence of asthma in a 'COPD' population and how to differentiate the two conditions.
  
  
  METHODS
  This was a prospective observational study of smokers fulfilling the Global Initiative for Chronic Obstructive Lung Disease definition of COPD [mean post-salbutamol forced expiratory volume in 1 s (FEV1) 66.9% predicted]. They were classified into 4 groups, as follows: (1) inhaled corticosteroid (ICS)-responsive asthma, defined by normalization of spirometry upon ICS treatment; (2) irreversible asthma, defined as airway obstruction for 1 year and bronchial biopsy indicating asthma; (3) COPD, in the presence of bilateral panlobular emphysema with bullae on high-resolution computed tomography, hypercapneic respiratory failure or bronchial biopsy indicating COPD, and (4) unclassified airflow limitation (AFL).
  
  
  RESULTS
  Eighty patients fulfilled the definition of COPD. The initial diagnosis was COPD in 57.5% and asthma in 42.5%. The final diagnosis was ICS-responsive asthma in 48 patients (60%), irreversible asthma in 8 (10%), COPD in 16 (20%) and unclassified AFL in 8 (10%). A normal transfer coefficient for carbon monoxide (KCO) and an FEV1 fluctuation ≥18% during 1 year of follow-up distinguished irreversible asthma and COPD. Seven of the 8 patients with irreversible asthma had improved FEV1 at the end of 1 year (median 320 ml compared with -29 ml in COPD). Five out of the 8 unclassified AFL cases had normal KCO and a large improvement in FEV(1) suggestive of irreversible asthma.
  
  
  CONCLUSIONS
  COPD, even in heavy smokers, includes cases of asthma. FEV1 fluctuation during 1 year is a novel concept which may distinguish irreversible asthma and COPD.
authors.affiliation: Department of Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia. falkassimi @ yahoo.com
authors.forename: Feisal A
authors.initials: FA
authors.lastname: Al-Kassimi
authors.forename: Abdullah A
authors.initials: AA
authors.lastname: Abba
authors.forename: Mohammed S
authors.initials: MS
authors.lastname: Al-Hajjaj
authors.forename: Esam H
authors.initials: EH
authors.lastname: Alhamad
authors.forename: Emad
authors.initials: E
authors.lastname: Raddaoui
authors.forename: Shaffi Ahamed
authors.initials: SA
authors.lastname: Shaikh
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology / Q000503:physiopathology; D003937:Diagnosis, Differential; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000175:diagnosis*; D012907:Smoking; D013147:Spirometry; D014797:Vital Capacity