A Long Term Evaluation of the Japanese Medical Payment System for Cataract Surgeries: Did the Medical Policy Reduce the Long Hospital Stay in Japan?

Abstract

In this paper, we conducted a long term survey of the cataract surgeries. The sample period was about 7 years, from July 2005 to March 2012. We evaluated the effects of three revisions of the medical payment system that were done in 2006, 2008 and 2010. For the analysis, the Box-Cox transformation model and Hausman test using Nawata's estimator were used for the length of stay (LOS) in hospitals, and the ordinary least squares method was used for the non-inclusive (mainly payments for surgeries) payments. We analyzed a dataset of 51,054 patients obtained from 60 hospitals (Hp1-60) where more than 300 one-eye cataract surgeries were performed during the period. For the LOS, we found that only the 2008 revision had significant impact on shortening the LOS but the other two did not. We also found very large differences among hospitals even after eliminating effects of patients' characteristics and type of principle diseases as previous studies. For non-inclusive payments 2006 and 2008 revisions had significant impacts and the differences among hospitals were much smaller than those of the LOS.

Asymptotic Efficiency of the Maximum Likelihood Estimator for the Box-Cox Transformation Model with Heteroscedastic Disturbances

“…Suppose that ij t is the explanatory variable of observation j in group i (for example, LOS of patient j in hospital i in Nawata and Kawabuchi [6]- [11]). I consider the BC model:…”

“…It is sometimes necessary to consider a model combining these two models. Nawata and Kawabuchi [6]- [11] analyzed length of stay (LOS) in Japanese hospitals using the BC model. They found that the variances among hospitals were often very different among hospitals even after the transformation.…”