Association Between Hospital Bed Supply and Health Outcomes: An Ecological Analysis and Narrative Review with Insights from Japan

Japan has achieved universal health coverage and one of the highest life expectancies worldwide. However, rapid population aging, workforce decline, fiscal pressures, and marked regional disparities threaten system sustainability. Despite a comparatively lower physician-to-population ratio among OECD countries, Japan maintains one of the highest hospital bed densities among OECD countries, reflecting a hospital-centered care model associated with prolonged stays and high inpatient expenditures.This narrative review with an ecological analysis examines the association between hospital bed supply and health outcomes, with insights from Japan. The quantitative analyses are explicitly hypothesis-generating and exploratory rather than causal. Publicly available national datasets from 2021–2022 were used to examine international differences in hospital bed and physician densities and to assess associations between hospital bed supply, per capita medical expenditure, life expectancy, and healthy life expectancy across Japan’s 47 prefectures. Descriptive statistics and Pearson correlation analyses were performed, with outcomes stratified by sex.Higher hospital bed density was consistently associated with increased inpatient expenditure but showed no positive relationship with life expectancy or healthy life expectancy. Among men, both indicators were negatively correlated with bed density, whereas no significant associations were observed among women.A case study of Yubari City, Hokkaido, suggests that large-scale bed reduction did not worsen mortality indicators and was accompanied by reduced medical expenditures and greater reliance on community-based and long-term care. Overall, these ecological, hypothesis-generating findings highlight potential inefficiencies of excess inpatient capacity. They also underscore the need for regionally tailored bed planning and strengthened primary and generalist care in Japan’s super-aged society.