# No Cost Sharing for Public Assistance Recipients and Health Service Usage in Japan

## TL;DR

Removing cost sharing for health care in Japan increased medical and dental visits among low-income individuals, especially for dental care.

## Contribution

This study empirically demonstrates the impact of no cost sharing on health service utilization among public assistance recipients in Japan.

## Key findings

- Outpatient medical and dental care utilization increased significantly after implementing no cost sharing for public assistance recipients.
- Dental care showed greater elasticity compared to medical care in response to the policy change.
- Eliminating cost sharing improved access to health services but may require measures to prevent overuse.

## Abstract

Is no cost sharing for health care services for public assistance recipients associated with increased medical and dental care utilization?

In this retrospective cohort study including 2893 patients certified for public assistance, outpatient care was associated with increased medical and dental settings after switching to no cost sharing. Dental care use showed significantly greater elasticity than medical care use.

No cost sharing on health care services for public assistance recipients was associated with higher outpatient medical and dental care utilization, highlighting the importance of monitoring the use of appropriate health care services before and after implementing no cost sharing.

This cohort study examines the association of cost sharing for health care services for public assistance recipients with medical and dental care utilization.

In Japan, the public assistance (PA) system for low-income individuals provides medical aid that covers all health care costs (no cost sharing). However, little is known about how health care service utilization changes after PA certification.

To examine the trajectories of outpatient medical and dental care utilization among PA recipients before and after PA certification.

Longitudinal data from a municipality in Japan participating in the Longevity Improvement Fair Evidence Study from 2017 to 2022 were used. Generalized estimating equations were used to calculate absolute differences and relative ratios in health care service utilization before and after PA certification. An interrupted time-series analysis (ITSA) was performed to examine the trends in health care service use based on monthly panel data. The elasticity of each health care service was also calculated. The participants were individuals who switched from National Health Insurance to PA and were 20 years and older. The analysis was performed in 2024.

PA certification.

Outpatient medical and dental care expenditures, visits, and unit costs per month from 1 year before to 1 year after PA certification.

Overall, 2893 study participants were analyzed (mean [SD] age, 54.2 [15.3] years; 1501 women [51.9%]). For outpatient medical care, the mean (SD) expenditures per month before and after PA certification were ¥16 565 (¥53 159) and ¥22 442 (¥53 443), respectively (converting to US dollars using the rate of ¥100 = $0.68 based on 2025 rates). For outpatient dental care, the mean (SD) expenditures per month before and after PA certification were ¥1727 (¥3726) and ¥3978 (¥6894), respectively. The ITSA showed significant increases in outpatient expenditure immediately after PA certification: ¥2681 (95% CI, 317-5046) and ¥2330 (95% CI, 1896-2764) in medical and dental care, respectively.

This study found that eliminating cost sharing under a PA system was associated with increased outpatient health service use, particularly for dental care. These findings highlight financial barriers to care among low-income populations and suggest that no cost-sharing policies can improve access but may require policy measures to address overuse.