• Our survey is among the first in Japan on quality of nursing homes.
• Unique survey both during and after the Covid-19 pandemic shows staffing matters.
• Facilities with more full-time equivalent staff per resident report fewer ulcers.
• This association between staffing and quality is robust across specifications.
• Staffing is not associated with use of restraints.

Japanese policymakers seek to develop a national system for monitoring nursing home quality, yet limited evidence is available about current quality of care and its relationship with strains on the direct-care workforce from Japan’s declining working-age population and growing cohorts of frail older adults.

We analyzed survey data from more than 1,000 Japanese nursing homes collected in 2020, 2022, and 2024. We linked these data with administrative data and conducted multivariable regressions assessing the relationship between direct-care staffing and two measures of quality of care: pressure ulcers and restraint use. We adjusted for facility characteristics and resident care need severity.

More full-time equivalent direct-care staff per resident is associated with fewer pressure ulcers among residents. An increase of one direct care worker full-time equivalent is associated with 2.74 (95% CI: [1.59, 3.89]) fewer patient ulcers in our baseline analysis and 3.17 (95% CI: [1.41, 4.93]) fewer patient ulcers when additionally controlling for staff turnover. Increases in the full-time equivalent numbers of care workers or nurses are also separately associated with fewer patient ulcers. Staffing is not statistically significantly associated with use of restraints.

Higher levels of full-time-equivalent direct-care staff per resident are associated with lower prevalence of pressure ulcers. These findings contribute to the limited evidence base on staffing and care quality in Japan as the country develops more systematic quality monitoring in long-term care.