Can the health insurance reforms stop an increase in medical expenditures for middle- and old-aged persons in Japan?

Using two-period panel data from the Nippon Life Insurance Research Institute, this paper tests the hypothesis that an increase in the self-pay ratio of medical expenditures associated with the Japanese health insurance reforms of April 2003 reduced household medical expenditures. We find that the increase in the self-pay ratio had a positive but insignificant effect on the share of medical expenses in household expenditure. However, when we employ the data as repeated cross-sectional observations to increase the sample size, the increase in the self-pay ratio has a significantly positive effect on the share of medical expenditures. This provides corroborating evidence that middle- and old-aged persons were unable to reduce their demand for medical services with the increase in the self-pay ratio. An additional finding is that medical services are a necessary good, particularly for those aged 61 years or older and those with medical expenditures accounting for a relatively high share of medical expenditures in high household expenditure.