Background
: Increasing the need of appropriate prediction formulas of pulmonary function parameters in Korean adults, interest about which affect the pulmonary function para-meters are increasing. Therefore we examined the relationship between pulmonary function pa-rameters derived from the forced expiratory spirogram and age, height, weight, and smoking amount in Korean middle aged men.

Methods : We analyzed the result of parameters derived from the forced expiratory spiro-gram in 1,954 men who enrolled in health examination of on corporation, from March 1995 to April 1996, who are aged from 45 to 59, and who have neither history of cardiopulmonary dis-ease nor lesions on chest X-ray. Pulmonary function was estimated by SPIROVIT SP-200(Switzerland). We evaluated the relationship between pulmonary function parameters and age, height, weight and smoking amount by multiple linear regression method.

Results : Mean age, height and weight were similar among current-smoker, ex-smoker and non-smoker group. Results of the effect on height-adjusted pulmonary function parameters ac-cording to smoking status were that FVC, FEV₁ and FEV₁/FVC showed no difference among three groups, but FEF 25-75% showed significant decrease in smokers group. To adjust the effects of age, height and weight about pulmonary function, we analyzed the parameters by multiple linear regression method. Results showed that all pulmonary function parameters showed nega-tive correlations with smoking amounts. We evaluated the effect of age, height and weight on pulmonary function parameters by multiple linear regression method. FVC and FEV₁showed negative correlations with age, positive correlations with height and no significant correlations with weight. FEV₁/FVC showed negative correlation only with age, and FEF 25-75% showed signi-ficant negative correlation with age and positive correlation with weight, but no significant cor-relation with height. We compared the predicted value estimated for Korean with that for American. Predicted value from prediction formulas for Korean were higher than that for American.

Conclusion : Smokers had significant decrease of FEF 25-75% compared with ex-smokers and non-smokers in Korean middle aged men. This indicates that smoking develops early changes on peripheral small airways. We have got predicton formulas for pulmonary function parameters in which FVC and FEV₁consisted of age and height and FEF 25-75% consisted of age and weight. Because prediction values estimated by Korean were higher than that by American, we must apply appropriate prediction formulas in Korean to Korean pulmonary function test.