OBJECTIVETo establish predictive equations of lung function for adults in urban areas in north China.

METHODSA survey was conducted in 600 male and 600 female healthy adults in the urban areas in north China. Five flow-volume test parameters were measured including forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). Stepwise multiple regression was carried out to establish the predicative equations for the parameters for male and female adults separately. The predicted values from these equations and those from other commonly used equations (such as ECCS equation and Knudson equation) were compared with the actual measurements in pulmonary function tests.

RESULTSFour flow-volume test parameters, namely FVC, FEV1, 25% forced expiratory flow (FEF25%), and FEF75%, showed obvious differences between the male and female adults, while FEV1/FVC was not correlated with gender. Multiple regression analysis showed that FVC, FEV1, FEF25% and FEF75% were positively correlated with height and negatively with age, and FEV1/FVC was negatively correlated with both height and age. The parameters were not affected by body weight. The predicted values from our equations were closer to the actual measurements than those calculated from other equations.

CONCLUSIONThe equations we established are more appropriate than the generally used equations for predicting lung functions in adults in north China urban areas.