The health service system in Japan has changed remarkably in the past 20 years. One feature of the changes is the introduction of evidence-based medicine (EBM) and another is medical economics. These approaches were not taken into account in the health services though they were very common in economic work. The rapidly aging population and economic crisis call for a new evaluation system in the health service field in Japan.
There are some studies on medical economics in clinical services at present; however few studies have been reported in preventive medicine. Especially, studies on medical economics in prim ary prevention in the community are very few in our country.
The activity of primary prevention is very important not only for medical economics but also for health promotion which is represented by The Healthy Japan 21. This article introduces some studies on medical economics for prevention in the United States and European Countries as well as some reports in the fields of industrial health in Japan.
Regretfully, only one study on medical economics has been found in the community; however this study did not show enough reliability and validity epidemiologically.
Kuno and his group conducted a new primary prevention study for aged people in a community. And medical economic evaluation programs are induced from the beginning in each project. These results may have a strong influence on primary prevention work in the community in Japan.

In order to study the effect of muscle exercise on the medical expenditure of the elderly, a three-year exercise program focusing on muscle activity was performed by an intervention group. Individual yearly medical expenditures were collected by 20 participants of the exercise group aver aging 65.2 years of age and 23 control subjects averaging 68.4 years of age with National Health Insurance coverage. Yearly medical expenditures for the exercise group were significantly lower than those of the control group at one and two years after entry. The expenditures increased by 62.6% from 1997 to 1999 in the control group, whereas they increased by only 16.8% for the exer cise group. The results suggest the possibility of the effectiveness of muscle exercise on the reduction in medical expenditure among the elderly.