Simplified Projection of the Insurance Premiums in the Greater Tokyo Area, 2020–2060

This study projected the future insurance premiums from 2020 to 2060 in the Greater Tokyo Area, given the expected increasing demand for nursing care. Estimating the change in the mean insurance premium rates by prefecture showed that in almost all prefectures, insurance premiums will reach their peak in Phase XIV (2040); however, in Gunma Prefecture, they will reach their peak in Phase VII (2020), and in Tokyo Prefecture, they will reach their peak in 2050. Next, verifying the index of increase in premiums by insured person across the entire Greater Tokyo Area from 2018 to 2060, calculated with the Phase V premium rates as 100, showed that over the entire duration, the kurtosis of the distribution tended to decrease gradually, while its variance tended to increase. It also showed an increase in the number of regions where the index became negative. Meanwhile, after 2020, there were also some regions where the indices became unusually high. In addition, verifying the distribution of the index of increase in premiums by insured person by prefecture showed that the variance of each prefecture’s distribution increased, just like that of the distribution across the Greater Tokyo Area.