Dosage and clinical outcomes of medical emergency team and conventional referral mediated unplanned intensive care admissions

Background: Unplanned intensive care unit (ICU) admission occurs via activation of medical emergency team (MET) and conventional ICU referral (CIR), i.e., ICU consultation. We aimed to compare the dosage, association with unplanned ICU admissions and hospital mortality between MET and CIR systems. Methods: We performed a retrospective, single centre observational study on unplanned ICU admissions from hospital wards between July 2017 and June 2018. We evaluated the dosage (expressed per 1000 admissions) and association of CIR and MET system with unplanned ICU admission using Chi-square test. The relationship (unadjusted and adjusted to Australia and New Zealand risk of death (ANZROD) and lead time) between unplanned ICU admission pathway (MET vs CIR) and hospital mortality was tested by binary logistic regression analysis [Odds ratio (OR) with 95% confidence interval (CI)]. Results: Out of 38,628 patients hospitalised, 679 had unplanned ICU admission (2%) with an ICU admission rate of 18 per 1000 ward admissions. There were 2153 MET and 453 CIR activations, producing a dosage of 56 and 12 per 1000 admissions, respectively. Higher unplanned ICU admission was significantly associated with CIR compared to MET activation (324/453 (71.5%) vs 355/2153 (16.5%) p < 0.001). On binary logistic regression, MET system was significantly associated with higher hospital mortality on unadjusted analysis (OR 1.65 (95% CI: 1.09–2.48) p = 0.02) but not after adjustment with ANZROD and lead time (OR 1.15 (95% CI: 0.71–1.86), p = 0.58). Conclusions: Compared to CIR, MET system had higher dosage but lower frequency of unplanned ICU admissions and lacked independent association with hospital mortality.