Reference values for pulmonary function in Asian Indians living in the United States

Objective: To establish reference values for pulmonary function in the Asian-Indian population living in the United States. Design: Five-year cross-sectional study of pulmonary function in healthy adult Asian Indians living in the United States, using American Thoracic Society guidelines for measuring pulmonary function. Setting: Measurement of pulmonary function in healthy nonsmoking Asian Indians in a pulmonary function laboratory or at festivals, picnics, and ceremonies where subjects could be conveniently recruited. Participants: Four hundred sixty subjects from a population of Asian Indians residing in the Chicago metropolitan area. Measurements: Spirometry was performed in all subjects with measurements of FEV1, FVC, and forced expiratory flow between 25% and 75% of vital capacity (FEF25-75). Lung volumes were measured in eighty subjects. Prediction equations for FEV1, FVC, and FEF25-75 were derived using multiple regression analysis. Results: Three hundred sixty-three subjects (226 men and 137 women) met the inclusion criteria. Spirometric values derived from our prediction equations, when compared to the values for whites from the selected studies in the literature, showed FVC to be 20 to 24% lower in men and 25 to 28% lower in women. FEV1 was 16 to 23% lower in men and 20 to 26% lower in women. Differences were not quite as large when compared to values from African Americans and other studies on Asians. Conclusions: We provide reference values for pulmonary function in nonsmoking Asian Indians living in the United States. These reference values should be used for evaluation of pulmonary function in this population.