Key points Is a critical illness event (death or transfer to the intensive care unit) associated with an increased short-term risk of critical illness in other patients in the same medical ward? Findings In this cohort study of 118,529 hospital admissions across 5 hospitals, patients were more likely to die or be transferred to an intensive care unit within 12 hours of another patient experiencing a critical illness event on the same ward. Meaning The findings suggest that critical illness events tend to cluster on medical wards, and efforts to better understand this association represent important opportunities to improve patient safety. |
Importance
Recognizing and preventing patient deterioration is important for hospital safety.
Aim
To investigate whether critical illness events (death in hospital or transfer to intensive care unit [ICU]) are associated with an increased risk of subsequent critical illness events for other patients in the same medical ward.
Design, scope and participants
Retrospective cohort study at 5 hospitals in Toronto, Canada, including 118,529 hospitalizations. Patients were admitted to general internal medicine wards between April 1, 2010 and October 31, 2017. Data were analyzed between January 1, 2020 and April 10, 2023.
Exhibitions
Severe illness events (in-hospital death or transfer to the ICU).
Main results and measures
The primary outcome was the composite of in-hospital death or transfer to the ICU. The association between critical illness events in the same ward at 6-hour intervals was studied using discrete-time survival analysis, adjusting for patient and situational factors.
The association between critical illness events in different comparable wards in the same hospital was measured as a negative control.
Results
The cohort included 118,529 hospitalizations (median age, 72 years [IQR, 56-83 years]; 50.7% men).
Death or transfer to the ICU occurred in 8785 hospitalizations (7.4%). Patients were more likely to experience the primary outcome after exposure to 1 prior event (adjusted odds ratio [AOR], 1.39; 95% CI, 1.30-1.48) and more than 1 prior event (AOR , 1.49; 95% CI, 1.33-1.68) in the previous 6-hour interval compared to no exposure.
Exposure was associated with increased odds of subsequent transfer to the ICU (1 event: AOR, 1.67; 95% CI, 1.54 to 1.81; >1 event: AOR, 2.05; 95% CI , 1.79 to 2.36), but not only to death (1 event: AOR, 1.08; 95% CI, 0.97-1.19; >1 event: AOR, 0.88; 95% CI %, 0.71-1.09).
There was no significant association between critical illness events on different wards within the same hospital.
Conclusions and relevance
The findings of this cohort study suggest that patients are more likely to be transferred to the ICU in the hours following the critical illness event of another patient on the same ward.
This phenomenon could have several explanations, including increased recognition of critical illness and preemptive transfers to the ICU, diversion of resources to the first event, or fluctuations in ward or ICU capacity. Patient safety can be improved by better understanding the clustering of ICU transfers on medical wards.
