A Comparison of Global Lung Initiative 2012 with Third National Health and Nutrition Examination Survey Spirometry Reference Values. Implications in Defining Obstruction

Rationale: Obstructive lung disease is diagnosed by a decreased ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC); however, there is no universally accepted lower limit of normal for the FEV1/FVC ratio. Current established reference values use the Third National Health and Nutrition Examination Survey (NHANES III) database. In 2012, the Global Lung Initiative (GLI) introduced GLI12, which is a compilation reference set that uses standard deviation values to define normal spirometry.Objectives: To evaluate the changes in classification of obstructive spirometry with use of GLI12 compared with NHANES III in a heterogeneous, multiracial population.Methods: We evaluated the spirometry studies conducted in our pulmonary function laboratory between January 2005 and December 2015. NHANES III reference equations were calculated to predict lower limits of normal for FEV1, FVC, and FEV1/FVC. GLI12 values were established using European Respiratory Society published computer softwar...