Economic Estimation of Nursing Services under the Diagnostic Procedure Combination/Per-Diem Payment System

Aim: The purpose of this study was to determine whether the amount of nursing services estimated under the classification of Nursing Need Degree is adequately evaluated for each Diagnostic Procedure Combination (DPC) reimbursement. Methods: A longitudinal cohort study design was employed to examine all 28,757 hospitalizations, except for those due to tuberculosis, in Hospital A in Japan between July 2008 and March 2010. We excluded the following patients from analysis: patients who were not applicable to the DPC system; patients who were hospitalized beyond the specified DPC period; and patients who were applicable to the specified hospital fee. We collected data from the administration system of medical business and Nursing Need Degree (NND). We calculated the mean of the hospital fee portion (i.e., fees for room and nursing services) per total number of nurses required and created a list of per-nurseday unit price for each DPC group, only if the number of patients included in the identical DPC group exceeded 20. We described about the number of assigned DPC codes, in such a way as to distribution of percent difference from the mean of hospital fee portion/total necessary number of nurses for each DPC group. In addition, we focused on the difference from the mean by 30%. Results: A significant correlation was found between the hospital fee portion and total number of nurses required under the DPC system. However, the distribution of percent differences among the mean of the hospital fee portion per total number of nurses required revealed that 39 of 179 DPC code groups were either underestimated or overestimated. The underestimated group included a number of obstetrics- and gynecology-related diseases, whereas the overestimated group included many non-surgical, cancer-related diseases. Conclusions: Our results significantly contribute to the identification of DPC codes that do not adequately reflect nursing services required under the present DPC payment system.