A retrospective registry-based study into the proportion of patients admitted to intensive care who have anaphylaxis as a principal diagnosis and their outcomes in Australia and New Zealand

Objective: To describe the proportion of patients admitted to intensive care who have anaphylaxis as a principal diagnosis and their subsequent outcomes in Australia and New Zealand. Design: Retrospective observational study of ICU admissions for severe anaphylaxis. Setting: ICU admissions recorded in the Australian and New Zealand Intensive Care Society Adult Patient Database between 2012 and 2022. Participants: Adults 16 years or older with severe anaphylaxis admitted to the ICU. Interventions: None. Main outcome measures: Proportion of patients admitted to ICU who have anaphylaxis as a principal diagnosis, mortality rate, ICU and hospital length of stay. Results: 7189 of the 7270 ICU admissions for severe anaphylaxis recorded between 2012 and 2022, were included in the analysis. This represented a proportion from 0.25% in 2012 to 0.43% in 2022. ICU and hospital mortality were 0.4% and 0.8%, respectively. The proportion of ICUs reporting at least one severe anaphylaxis each year increased from 61.7% in 2012 to 83.0% in 2022. Most of the patients were discharged home (92.6%, n = 6660). Increasing age (OR = 1.055; 95%CI: 1.008-1.105)- 1.105) and SOFA scores (OR = 1.616; 95%CI: 1.265-2.065),- 2.065), an immunosuppressive chronic condition (OR = 16.572; 95%CI: 3.006- 91.349) and an increasing respiratory rate above 16 breaths/min (OR = 1.116; 95%CI: 1.057-1.178)- 1.178) predicted in-hospital mortality in patients with anaphylaxis, while higher GCS decreased in-hospital mortality (OR = 0.827; 95%CI: 0.705-0.969).- 0.969). Conclusions: The overall proportion of patients admitted to ICU who have anaphylaxis as a principal diagnosis has increased. In-hospital mortality remains low despite the need for vital organ support. Further studies should investigate these identified factors that may predict in-hospital mortality among these patients. Trial registration: Not applicable.