Associations of the staffing structure of intensive care units and high care units on in-hospital mortality among patients with sepsis: a cross-sectional study of Japanese nationwide claims data

Abstract

Objective: The objective was to analyse the associations of intensive care unit (ICU) and high care unit (HCU) organisational structure on in-hospital mortality among patients with sepsis in Japan's acute care hospitals.

Design: Multicentre cross-sectional study.

Settings: Patients with sepsis aged ≥18 years who received critical care in acute care hospitals throughout Japan between April 2018 and March 2019 were identified using the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB).

Interventions: None.

Participants: 10 968 patients with sepsis were identified. ICUs were categorised into three groups: type 1 ICUs (fulfilling stringent staffing criteria such as experienced intensivists and high nurse-to-patient ratios), type 2 ICUs (less stringent criteria) and HCUs (least stringent criteria).

Primary outcome measure: The study's primary outcome measure was in-hospital mortality. Cox proportional hazards regression analysis was performed to examine the impact of ICU/HCU groups on in-hospital mortality.

Results: We analysed 2411 patients (178 hospitals) in the type 1 ICU group, 3653 patients (422 hospitals) in the type 2 ICU group and 4904 patients (521 hospitals) in the HCU group. When compared with the type 1 ICU group, the adjusted HRs for in-hospital mortality were 1.12 (95% CI 1.04 to 1.21) for the type 2 ICU group and 1.17 (95% CI 1.08 to 1.26) for the HCU group.

Conclusion: ICUs that fulfil more stringent staffing criteria were associated with lower in-hospital mortality among patients with sepsis than HCUs. Differences in organisational structure may have an association with outcomes in patients with sepsis, and this was observed by the NDB.

Keywords: adult intensive & critical care; cross-sectional studies; mortality; quality improvement; retrospective studies.

Figure 1. Flow chart of patient selection. HCU, high care unit; ICU, intensive care unit.

Figure 2. Adjusted survival curves of the ICU and HCU groups using the Cox proportional hazards model. Type 1 ICU group (black line), type 2 ICU group (black dotted line) and HCU group (grey line). After adjusting for the covariates, the type 1 ICU group had the highest survival rate, followed by the type 2 ICU group. HCU, high care unit; ICU, intensive care unit.