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Volchenboum SL, Mayampurath A, Göksu-Gürsoy G, Edelson DP, Howell MD, Churpek MM. Association Between In-Hospital Critical Illness Events and Outcomes in Patients on the Same Ward. JAMA. 2016;316(24):2674–2675. doi:10.1001/jama.2016.15505
Copyright 2016 American Medical Association. All Rights Reserved.
Major critical illness events, such as cardiopulmonary arrest and intensive care unit (ICU) transfer, disrupt workflow in a hospital ward. Other patients on the same ward may receive inadequate attention, especially if their care team is distracted by the emergency. Most studies have concentrated on patient-level variables associated with outcomes.1-3 To our knowledge, no study has quantified the risk to ward occupants associated with patients on the same ward experiencing critical illness.
This observational cohort study of consecutive adult admissions (2009-2013) at the University of Chicago Medicine where rapid-response teams were used included 13 medical-surgical wards that were geographically distinct areas, had patient-nurse ratios of 4:1 on average and 1 charge nurse, and had approximately 20 beds per ward. Physician teams consisted of 1 attending and 2 to 3 resident trainees or a hospitalist. The university’s institutional review board granted a waiver of informed consent.
The primary outcome was a composite of cardiac arrest and ICU transfer.3 The primary exposure was the number of patients on the same ward experiencing a critical illness event (cardiac arrest, ICU transfer, or death) anytime during the prior 6 hours.4 Discrete time survival analysis modeling (using fixed 6-hour blocks of time beginning at ward admission) was used to adjust for severity of illness (electronic Cardiac Arrest Risk Triage score3), time of day (day: 7 am-5 pm; evening: 5 pm-10 pm; night: 10 pm-7 am), weekday vs weekend, total number of ward patients, proportion of occupied ICU beds,5 and specific ward.
Analyses were performed using R (R Project for Statistical Computing), version 3.1, with a 2-sided P<.05 denoting statistical significance.
Of 83 723 admissions, 4286 experienced the primary outcome (179 cardiac arrests and 4107 ICU transfers). Compared with patients without an event, those with an event were older (60 years vs 57 years), less likely to be female (50% vs 53%), and had a longer median length of stay (12.8 days vs 3.0 days) (all P < .001).
The likelihood of cardiac arrest or ICU transfer within the next 6 hours was greater when 1 event (5.0 [95% CI, 4.6-5.6] per 1000-patient 6-hour blocks) or more than 1 event (7.1 [95% CI, 5.0-10.3] per 1000-patient 6-hour blocks) occurred during the prior 6 hours compared with no event (3.6 [95% CI, 3.5-3.8] per 1000-patient 6-hour blocks). In the fully adjusted model (Table 1), when 1 or more patients developed critical illness, other ward patients’ risks for cardiac arrest or ICU transfer increased over the next 6 hours (1 event: odds ratio [OR], 1.18 [95% CI, 1.07-1.31], adjusted absolute risk increase of 0.6 per 1000-patient 6-hour blocks); >1 event: OR, 1.53 [95% CI, 1.03-2.18], adjusted absolute risk increase of 1.9 per 1000-patient 6-hour blocks). Results remained statistically significant when changing the time window to 3 and 12 hours (Table 2).
The association was not statistically different during nighttime hours (1 event: OR, 1.42 [95% CI, 1.17 to 1.71], P = .06 for interaction; >1 event: OR, 2.23 [95% CI, 1.07 to 4.08], P = .20 for interaction), although this analysis is likely underpowered. Severity scores for ICU transfer patients exposed and not exposed to a critical illness event during the prior 6 hours were not statistically different (mean, 39 vs 37, respectively; mean difference of 2 [95% CI, −11 to 7]).
Mortality was not significantly different between the exposed and not exposed groups (14% vs 14%, P = .90). Critical illness events were associated with a decrease in other patients being discharged from the hospital within the next 6 hours (1 event: OR, 0.94 [95% CI, 0.92-0.96]; >1 event: OR, 0.95 [95% CI, 0.87-1.04]).
Development of a critical illness event in a patient was associated with a higher risk of cardiac arrest or ICU transfer in other patients on the same ward. Although the absolute increased risk was small, these events were associated with high morbidity and mortality.
The association may be explained by the diversion of resources to critically ill patients, which may result in caregivers being less attentive to other ward patients. Study limitations include the retrospective design, single center, unavailability of patient-specific clinician information or reason for admission, and possible residual confounding.
Corresponding Author: Matthew M. Churpek, MD, MPH, PhD, Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, 5841 S Maryland Ave, MC 6076, Chicago, IL 60637 (email@example.com).
Author Contributions: Drs Volchenboum and Churpek had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Concept and design: Volchenboum, Edelson, Howell, Churpek.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Volchenboum, Mayampurath, Göksu-Gürsoy.
Critical revision of the manuscript for important intellectual content: Volchenboum, Mayampurath, Edelson, Howell, Churpek.
Statistical analysis: Mayampurath, Göksu-Gürsoy, Howell, Churpek.
Administrative, technical, or material support: Volchenboum, Edelson, Howell, Churpek.
Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Drs Edelson and Churpek reported having a patent pending for risk stratification algorithms for hospitalized patients. Dr Edelson also reported ownership interest in Quant HC, which is developing products for risk stratification of hospitalized patients; receiving research support and honoraria from Philips Healthcare; and receiving honoraria from Early Sense. Dr Churpek also reported receiving honoraria from Chest. No other disclosures were reported.
Funding/Support: Dr Churpek is supported by career development award K08 HL121080 from the National Heart, Lung, and Blood Institute.
Role of the Funder/Sponsor: The National Heart, Lung, and Blood Institute had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
Additional Contributions: We thank Timothy Holper, MS, MA, and Stacie Landron, RN, MS (both with the Center for Research Informatics, University of Chicago), for assistance with data extraction and Nicole Twu, MS (Department of Medicine, University of Chicago), for administrative support. None of these individuals received compensation for their contributions.
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