title: Instability in the COPD diagnosis upon repeat testing vary with the definition of COPD.
abstract: BACKGROUND
  A low FEV1/FVC from post-bronchodilator spirometry is required to diagnose COPD. Both the FEV1 and the FVC can vary over time; therefore, individuals can be given a diagnosis of mild COPD at one visit, but have normal spirometry during the next appointment, even without an intervention.
  
  
  METHODS
  We analyzed two population-based surveys of adults with spirometry carried out for the same individuals 5-9 years after their baseline examination. We determined the factors associated with a change in the spirometry interpretation from one exam to the next utilizing different criteria commonly used to diagnose COPD.
  
  
  RESULTS
  The rate of an inconsistent diagnosis of mild COPD was 11.7% using FEV1/FVC <0.70, 5.9% using FEV1/FEV6 <the lower limit of the normal range, LLN and 4.1% using the GOLD stage 2-4 criterion. The most important factor associated with diagnostic inconsistency was the closeness of the ratio to the LLN during the first examination. Inconsistency decreased with a lower FEV1.
  
  
  CONCLUSIONS
  Using FEV1/FEV6 <LLN or GOLD stage 2-4 as the criterion for airflow obstruction reduces inconsistencies in the diagnosis of mild COPD. Further improvement could be obtained by defining a borderline zone around the LLN (e.g. plus or minus 0.6 SD), or repeating the test in patients with borderline results.
authors: Sleep Clinic, National Institute of Respiratory Diseases, Mexico City, Mexico.
authors: Rogelio
authors: R
authors: Perez-Padilla
authors: Postgraduate program on Epidemiology, Federal University of Pelotas, Pelotas, Brazil.
authors: Fernando C
authors: FC
authors: Wehrmeister
authors: Pulmonary Division, Hospital Universitario de Caracas, Universidad Central de Venezuela, Caracas, Venezuela.
authors: Maria
authors: M
authors: Montes de Oca
authors: Faculty of Medicine, University of the Republic, Montevideo, Uruguay.
authors: Maria Victorina
authors: MV
authors: Lopez
authors: Federal University of Sao Paulo, Sao Paulo, Brazil.
authors: Jose R
authors: JR
authors: Jardim
authors: Faculty of Medicine, University of the Republic, Montevideo, Uruguay.
authors: Adriana
authors: A
authors: Muino
authors: Pontificia Universidad Catolica de Chile, Santiago, Chile.
authors: Gonzalo
authors: G
authors: Valdivia
authors: Pontificia Universidad Catolica de Chile, Santiago, Chile.
authors: Julio
authors: J
authors: Pertuze
authors: Postgraduate program on Epidemiology, Federal University of Pelotas, Pelotas, Brazil.
authors: Ana Maria B
authors: AM
authors: Menezes
mesh_terms: D000328:Adult; D001993:Bronchodilator Agents / Q000494:pharmacology; D003948:Diagnostic Techniques, Respiratory System; D018450:Disease Progression; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D013147:Spirometry
chemical_list: D001993:Bronchodilator Agents