A global comparison of predicting equations on spirometry in the male population.

A multiple regression model considering dependent variables like vital capacity (VC), forced expiratory volume in one second (FEV1) and peak expiratory flow rate (PEFR) and age and height as independent variables for the adult male population, which includes whites of European descent and non-whites was reviewed to evaluate the role of lung function status following standardization of age and height. Non-whites showed 0.19 litre decline in VC per decade of life as compared to 0.24 litres observed in the whites of European descent. Mean VC increased 0.05 litres per centimetre in non-whites and whites. The variation in the constant term in the regression equation determined the difference between the racial groups. Like VC, FEV1 showed ethnic differences similar to those of VC. However, the magnitude of the variation in the predicted values of FEV1 was found to be less than that observed in VC. When related to VC, FEV1 showed little difference between most European populations, New Guyanaese, Indians, Negroes, Africans and Chinese because FEV1/FVC ratio had a very narrow range between 77 and 80%.