Intensive care unit strain and mortality risk in patients admitted from the ward in Australia and New Zealand

Purpose: ICU strain (low number of available beds) may be associated with a delay and altered threshold for ICU admission and adverse patient outcomes. We aimed to investigate the impact of ICU strain on hospital mortality in critically ill patients admitted from wards across Australia and New Zealand. 

Materials and methods: Ward patient admitted to ICU and ICU bed data at 137 hospitals were accessed between January 2013 and December 2016. ICU strain was classified as low (≤0.5 patients admitted per available ICU bed in a 6-h block), medium (0.5 to ≤1) or high (>1). Logistic regression models were used to examine the relationship between ICU strain and hospital mortality. 

Results: 57,844 ICU admissions were analysed, with the majority (64.4%) admitted to medium-strain ICUs. Those admitted to high-strain ICUs spent longer in hospital prior to ICU than medium-strain or low-strain ICUs. After adjusting for confounders those admitted to high-strain ICUs [OR 1.24 (95%CI 1.14–1.35)] or medium-strain ICUs [OR 1.18 (95%CI 1.09–1.27)], (p < 0.001) had a higher risk of death compared low-strain ICUs. 

Conclusion: ICU strain is associated with longer times in hospital prior to ICU admission and was associated with increased risk of death in patients admitted from ward.