Critical care access and outcomes in residents of inpatient-care catchment areas with and without ICUs: a nationwide cohort study in Japan

Background: In Japan, many secondary medical areas (SMAs), defined as regional self-sufficient inpatient-care planning units, are not equipped with intensive care unit (ICU) beds. We aimed to describe the national distribution of SMAs without ICUs, compared post-arrival outcomes among ICU-admitted patients, and evaluated ICU access and mortality among critically ill patients. Methods: This retrospective cohort study linked data from the Diagnosis Procedure Combination database with the Hospital Bed Function Report of 2022. The primary exposure was residence in an SMA without ICU beds. Outcomes were assessed using multivariate generalized linear models. Findings: Among 335 SMAs, 140 (41.8%) lacked ICU beds, encompassing 11.6% of the national population and 46.0% of the land area. Among the 282,894 ICU-admitted patients, residents of SMAs without ICUs travelled substantially farther to reach an ICU (median 32.4 vs. 5.7 km), but had no statistically significant difference in adjusted in-hospital mortality (adjusted risk difference, -0.38 percentage points; 95% confidence interval [CI], -0.81 to 0.05). In a separate analysis of 467,200 critically ill patients, those living in SMAs without ICUs had lower ICU admission rates (24.9% vs. 35.6%) and statistically significant but small increase in adjusted in-hospital mortality (adjusted risk difference +0.96 percentage points; 95% CI: 0.17-1.75). Interpretation: Nearly half of SMAs lack ICU beds. While post-arrival ICU outcomes were similar, residence in an SMA without ICUs was associated with reduced ICU access and higher mortality among critically ill patients. Funding: Ministry of Health, Labor and Welfare, Japan; and Japan Agency for Medical Research and Development.