[The effect of sharing medical costs for the aged 70 or more on the financial balance of the health insurance society].

The rapid increase of the proportion of older persons in society has made the problem of medical costs more important. Although medical cost-sharing for those aged 70 or more is decided by their medical costs and by the current proportion of such persons in the Society, it is not constant throughout the Society. The study evaluated the contribution ratio of medical cost-sharing for those aged 70 or more to the financial balance of the Society. In addition, characteristics of the Society associated with medical cost-sharing for those aged 70 or more were analyzed. The results are as follows. 1) Medical cost-sharing for those aged 70 or more was the greatest factor in the financial balance of the Society with a contribution ratio of as much as 55.2%. 2) Multiple regression analysis disclosed that dependent ratio, the average monthly salary, the area, the rate of those aged 70 or more and the average age of the Society members are significant in medical cost-sharing for those aged 70 or more. 3) Dependent ratio and the average monthly salary are the most important characteristics among those associated with medical cost-sharing for those aged 70 or more. A higher dependent ratio and a lower average monthly salary are related to higher cost-sharing. This is also related to geographic factors as cost-sharing in western Japan is higher than in eastern Japan. The lower rate of those aged 70 or more and the higher average age of the Society members are related to the higher cost-sharing.