Comparison of Regression Equations For Predicted Values of Pulmonary Function Parameters In North Indian Subjects.

ABSTRACT

Pulmonary function parameters are the most important and widely used exploratory tool in respiratory disorders. Most of the studies on these parameters describe lung capacities and flow rates in terms of absolute values. There are various equations to derive the predicted values of these parameters. Most of these equations are framed for Caucasian, American or Africans, but are frequently used in Indian subjects. There are very few equations for Indian subjects, which are also region specific. Hence, the present study was undertaken to compare the various regression equations for calculating predicted parameters in North Indian subjects. We used eight regression equations which are frequently used for calculating predicted values. The data of 75 Indian healthy subjects was used in these equations for comparison. The regression equations provided predicted value of pulmonary function parameters which varied markedly (0.24-123%) based on type of regression formula used. The closet seems to be Chatterjee and Vijayan equation. The anthropometric variable used in these equations can have a lot of bearing on the predicted values. However, based on literature and our experience of using eight regression equations, we found that none of these is perfectly suited for North Indian subjects.