抄録
In pneumonia, different medical treatment fees were set for less than 15 years old and aged 15 and over with the amendment in 2012. A purpose of this study is to investigate the suitable age used for a setup of a treatment fee by using decision tree analysis method which made the ratio of FFS (fee for service) / totalfee-for-PDPS (per-diem payment system) the dependent variable and by using DPC survey data before and after the amendment. In the results, the value of age which were appeared in the first branch in the tree were different between before and after amendment. Three kinds of generation (<5, 5〜73, 73<), not 15 years old, were found after amendment.