Table 1

Definitions of airway obstruction

Self-reported diagnosis of chronic bronchitis or emphysema “self report”See text for description of variables used
FEV1/FVC <0.70 and FEV1 <80% pred#GOLD Stage IIA 12
FEV1/FVC < lower limit of normalSee text for comparability to ATS guidelines 13
FEV1/FVC <88% pred in males and <89% pred in females “per cent predicted”See text for comparability to ERS guidelines 14
FEV1/FVC <0.70 “fixed ratio” #“Clinical” definition 6, equivalent to GOLD Stage I 12
  • FEV1: forced expiratory volume in one second

  • FVC: forced vital capacity

  • % pred: % predicted

  • GOLD: Global Initiative for Chronic Obstructive Lung Disease

  • ATS; American Thoracic Society

  • ERS: European Respiratory Society

  • #: GOLD specifies that all FEV1 values should refer topostbronchodilator FEV1. The third National Health and Nutrition Examination Survey (NHANES III) did not include reversibility testing 12

  • : the ATS specifies that spirometry should be performed pre- and postbronchodilator. NHANES III did not include reversibility testing 13