School-Based Fluoride Mouth-Rinse Programs and Dental Caries Treatment Expenditure: An Ecological Study of the NDB Open Data Japan.

OBJECTIVES

The prevalence of dental caries is high in Japan, leading to a huge burden of overall expenditure on dental caries treatment for the population. School-based fluoride mouth-rinse (S-FMR) has been implemented as a public health intervention. However, its cost-effectiveness remains unclear, where universal health insurance covers a broad range of dental treatments at relatively low cost. The aim of the study was to determine whether S-FMR is associated with lower dental caries treatment expenditure in Japan, where the universal health insurance system widely covers dental treatments. In addition, the cost-benefit of S-FMR was estimated.

METHODS

This ecological study examined the association between S-FMR coverage and dental caries treatment expenditure in all 47 prefectures of Japan. Data were obtained from the National Database of Health Insurance Claims and Specific Health Checkups of Japan open data (NDB Open Data Japan), national survey data on the prevalence of S-FMR, and other census data for each prefecture. The outcome variable was the average annual treatment expenditure of for children aged 5-14 per child. The explanatory variable was the S-FMR coverage of children per prefecture, divided into quartiles: (Q1) 0.0%-0.48%, (Q2) 0.54%-6.9%, (Q3) 7.2%-25.0% and (Q4) 26.9%-80.4%. Linear regression analysis was performed with adjustment for the number of dental clinics per 100 000 individuals, per capita prefectural income, and percentage of the population aged between 5 and 14 years.

RESULTS

The dental caries treatment expenditure was lower in prefectures with higher S-FMR coverage: (Q1) 2378 JPY, (Q2) 2215 JPY, (Q3) 2217 JPY and (Q4) 2065 JPY. Linear regression analysis showed that, compared to the prefectures with the lowest S-FMR coverage, the prefectures with the highest coverage exhibited significantly lower per person dental caries treatment expenditure by 186.0 (95% CI = 96.6, 275.4) JPY. When annual cost of S-FMR per person was lower, 200 JPY, S-FMR would save 0.9 billion JPY if all prefectures change from Q1 to Q4 (approximately 8.2 million USD).

CONCLUSIONS

Although public healthcare insurance in Japan covers most dental treatments at a relatively low cost, the current findings suggest that S-FMR could still be a cost-effective public health intervention.