Development of prediction equation of diffusing capacity of lung for koreans

Background: The diffusing capacity of the lung is influenced by multiple factors such as age, sex, height, weight, ethnicity and smoking status. Although a prediction equation for the diffusing capacity of Korea was proposed in the mid-1980s, this equation is not used currently. The aim of this study was to develop a new prediction equation for the diffusing capacity for Koreans. Methods: Using the data of the Korean National Health and Nutrition Examination Survey, a total of 140 nonsmokers with normal chest X-rays were enrolled in this study. Results: Using linear regression analysis, a new predicting equation for diffusing capacity was developed. For men, the following new equations were developed: carbon monoxide diffusing capacity (DLco)=–10.4433–0.1434×age (year)+0.2482×heights (cm); DLco/alveolar volume (VA)=6.01507–0.02374×age (year)–0.00233×heights (cm). For women the prediction equations were described as followed: DLco=–12.8895–0.0532×age (year)+0.2145×heights (cm) and DLco/VA=7.69516–0.02219×age (year)–0.01377×heights (cm). All equations were internally validated by k-fold cross validation method. Conclusion: In this study, we developed new prediction equations for the diffusing capacity of the lungs of Koreans. A further study is needed to validate the new predicting equation for diffusing capacity.