Comparison between predicted equations obtained by standard Japanese values and present predicted equations for vital capacity and forced expiratory volume in one second

: Until recently, predicted values of vital capacity (VC) and forced expiratory volume in one second (FEV1) have been calculated with Baldwin's equation (VC-B) and Berglund's equation (FEV1-B) respectively, in Japan. Due to several problems using these equations, new prediction equations of VC (VC-J) and FEV1 (FEV1-J), which were created using data from healthy Japanese, were provided by the Japanese Respiratory Society in 2001. In the present study, we studied the validity of these prediction equations. Also, we compared the outcomes of patients who match respiratory handicap "indexes" with VC-B and VC-J. The subjects were all adult patients whose respiratory function was tested in Asahikawa Medical College Hospital between 1998 and 2006. Cases which were diagnosed as contractive respiratory disorder increased approximately 2-fold when %VC was calculated with VC-J compared with VC-B. Grade 4 or higher respiratory handicap scores increased 20% if the index was calculated with VC-J compared with VC-B. There was no significant difference in mortality between the respiratory handicap grade 3 scores calculated with VC-J and VC-B. Also, there was no significant difference in mortality between grade 4 respiratory handicap scores calculated with VC-J and VC-B. These findings suggest that the prediction equations using Japanese data increase the number of predicted respiratory disorders, and those additional cases have the same prognoses as those cases diagnosed with the former criteria.