Population impact of different definitions of airway obstruction

There is currently no consensus on the criteria for diagnosing chronic obstructive pulmonary disease. This study evaluated the impact of different definitions of airway obstruction on the estimated prevalence of obstruction in a population-based sample. Using the Third National Health and Nutrition Examination Survey, obstructive airway disease was defined using the following criteria: 1) self-reported diagnosis of chronic bronchitis or emphysema; 2) forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) 50 yrs, the fixed ratio criteria produced the highest rate estimates. For all subgroups tested, the GOLD Stage II criteria produced lower estimates than other spirometry-based definitions. Different definitions of obstruction may produce prevalence estimates that vary by >200%. International opinion leaders should agree upon a clear definition of chronic obstructive pulmonary disease that can serve as a population-based measurement criterion as well as a guide to clinicians.