Background and aimsReducing health care costs through preventive geriatric care has become a high priority in Japan. We analyzed data from a randomized controlled trial to examine the effects of a preventive home visit program on health care costs among ambulatory frail elders.MethodsStructured preventive home visits by nurses or care managers were provided to the visit group every 6 months over 2 years. The enrolled participants (N = 323) were randomly assigned to either the visit group (N = 161) or the control group (N = 162). We analyzed the health care costs, including the costs for hospitalizations and outpatient clinic utilization for participants who had health care insurance from the local government (N = 307). The visit group included 154 individuals in the visit group and 153 people in the control group.ResultsTotal health care costs over the study period were not significantly different between groups, but at most monthly time points costs and those for outpatient clinic utilization in the visit group were lower than those in the control group. Hospitalizations, which accounted for more than ¥500,000 JPY per month, were less likely to occur more often among participants in the visit group (N = 71) than in the control group (N = 113) (OR = 0.63; p = 0.002).ConclusionsThese results suggest that a preventive home visit program may reduce monthly health care costs, primarily by reducing hospitalization costs.