title: Diagnostic Instability and Reversals of Chronic Obstructive Pulmonary Disease Diagnosis in Individuals with Mild to Moderate Airflow Obstruction.
abstract: Chronic obstructive pulmonary disease (COPD) is a chronic, progressive disease, and reversal of COPD diagnosis is thought to be uncommon.
  
  
  
  To determine whether a spirometric diagnosis of mild or moderate COPD is subject to variability and potential error.
  
  
  
  We examined two prospective cohort studies that enrolled subjects with mild to moderate post-bronchodilator airflow obstruction. The Lung Health Study (n = 5,861 subjects; study duration, 5 yr) and the Canadian Cohort of Obstructive Lung Disease (CanCOLD) study (n = 1,551 subjects; study duration, 4 yr) were examined to determine frequencies of (1) diagnostic instability, represented by how often patients initially met criteria for a spirometric diagnosis of COPD but then crossed the diagnostic threshold to normal and then crossed back to COPD over a series of annual visits, or vice versa; and (2) diagnostic reversals, defined as how often an individual's COPD diagnosis at the study outset reversed to normal by the end of the study.
  
  
  
  Diagnostic instability was common and occurred in 19.5% of the Lung Health Study subjects and 6.4% of the CanCOLD subjects. Diagnostic reversals of COPD from the beginning to the end of the study period occurred in 12.6% and 27.2% of subjects in the Lung Health Study and CanCOLD study, respectively. The risk of diagnostic instability was greatest for subjects whose baseline FEV1/FVC value was closest to the diagnostic threshold, and the risk of diagnostic reversal was greatest for subjects who quit smoking during the study.
  
  
  
  A single post-bronchodilator spirometric assessment may not be reliable for diagnosing COPD in patients with mild to moderate airflow obstruction at baseline.
authors.affiliation: 1 The Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Shawn D
authors.identifier: 0000-0002-4762-3542
authors.initials: SD
authors.lastname: Aaron
authors.affiliation: 2 Department of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada; and.
authors.forename: Wan C
authors.initials: WC
authors.lastname: Tan
authors.affiliation: 3 Department of Medicine, Faculty of Medicine, and.
authors.forename: Jean
authors.initials: J
authors.lastname: Bourbeau
authors.affiliation: 2 Department of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada; and.
authors.forename: Don D
authors.initials: DD
authors.lastname: Sin
authors.affiliation: 1 The Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Robyn H
authors.initials: RH
authors.lastname: Loves
authors.affiliation: 1 The Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Jenna
authors.initials: J
authors.lastname: MacNeil
authors.affiliation: 1 The Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada.|4 Desautels Faculty of Management, McGill University, Montreal, Quebec, Canada.
authors.forename: George A
authors.initials: GA
authors.lastname: Whitmore
mesh_terms: D000328:Adult; D000402:Airway Obstruction / Q000503:physiopathology*; D015331:Cohort Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D012720:Severity of Illness Index; D013147:Spirometry; D014797:Vital Capacity / Q000502:physiology
keywords: chronic obstructive pulmonary disease; diagnosis; lung function variability; spirometry