1999 Volume 6 Pages 19-36
The purpose of this study was to examine the influence of the copayment rate on the outpatient service utilization.
700 middle-aged male residents in a metropolitan area of Tokyo were surveyed with selfreported questionnaire. Firstly, the incidence and quantity of the outpatient service utilization were compared between the 10% copayment group and the 30% copayment group. Secondly, the effect of two-way interaction between copayment rate and income on the incidence and quantity of utilization were examined. The results were as follows.
1) Probability of any use of outpatient service in one year was higher in the 10% copayment group than in the 30% copayment group.
2) There was no significant difference in the quantity of utilization in a year between two groups.
3) No interactions were observed between copayment rate and income on the incidence and quantity of utilization.
We discussed the effect of the copayment rate on the outpatient service utilization in the following two ways: (1) the effect was direct. (2) the effect was confounding.
