Table 2.

Annual counts and relative incidence rates of Code Grey events in ICU across the six-year study period.

Year	2015	2016	2017	2018	2019	2020
Annual count ICU Code Grey events	77	105	139	151	131	204
Annual total ICU occupied bed days	7448	7987	8973	9297	9607	9527
IRR (95% CI)	Reference	1.3 (0.7–2.4)	1.4 (0.8–2.6)	1.5 (0.8–2.9)	1.3 (0.7–2.5)	2.0 (1.2–3.5)

IRR = incidence rate ratio, relative to 2015 count, controlling for exposure (days of ICU stay), with standard errors adjusted for 14,085 clusters in individual patients within a univariable Poisson regression model.

Reference = reference year for calculations of IRR.