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Crit Care Med. 2015 Aug;43(8):1587-94. doi: 10.1097/CCM.0000000000001015.

Patient Mortality Is Associated With Staff Resources and Workload in the ICU: A Multicenter Observational Study.

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1Hospices Civils de Lyon, Pôle Information Médicale Évaluation Recherche, Lyon, France. 2Université Claude Bernard Lyon 1, Faculté de Médecine Lyon Est, Lyon, France. 3Hospices Civils de Lyon, Service de Réanimation Médicale, Hôpital de la Croix Rousse, Lyon, France. 4IMRB INSERM 955Eq13, Créteil, France. 5Health Services and Performance Research Lab, Lyon, France 6Department of Anesthesiology and Critical Care Medicine, Hospices Civils de Lyon, Croix Rousse Hospital, Lyon, France. 7Hospices Civils de Lyon, Service de Réanimation Neurologique, Hôpital Pierre Wertheimer, Groupement Hospitalier Est, Lyon, France. 8Hospices Civils de Lyon, Fédération Hospitalo-Universitaire d'Anesthésie-Réanimation, Hôpital Neurologique P. Wertheimer, France. 9Hospices Civils de Lyon, Service d'Anesthésie Réanimation, Centre Hospitalier Lyon Sud, Lyon, France. 10Université Claude Bernard Lyon 1, Faculté de Médecine Lyon Sud, Lyon, France. 11Hospices Civils de Lyon, Hôpital Louis Pradel, Service d'Anesthésie-Réanimation, Lyon, France. 12Anesthesiology and Intensive care Medicine, Edouard Herriot hospital, Hospices Civils de Lyon, University Claude Bernard Lyon 1, Lyon, France.



Matching healthcare staff resources to patient needs in the ICU is a key factor for quality of care. We aimed to assess the impact of the staffing-to-patient ratio and workload on ICU mortality.


We performed a multicenter longitudinal study using routinely collected hospital data.


Information pertaining to every patient in eight ICUs from four university hospitals from January to December 2013 was analyzed.


A total of 5,718 inpatient stays were included.




We used a shift-by-shift varying measure of the patient-to-caregiver ratio in combination with workload to establish their relationships with ICU mortality over time, excluding patients with decision to forego life-sustaining therapy. Using a multilevel Poisson regression, we quantified ICU mortality-relative risk, adjusted for patient turnover, severity, and staffing levels. The risk of death was increased by 3.5 (95% CI, 1.3-9.1) when the patient-to-nurse ratio was greater than 2.5, and it was increased by 2.0 (95% CI, 1.3-3.2) when the patient-to-physician ratio exceeded 14. The highest ratios occurred more frequently during the weekend for nurse staffing and during the night for physicians (p < 0.001). High patient turnover (adjusted relative risk, 5.6 [2.0-15.0]) and the volume of life-sustaining procedures performed by staff (adjusted relative risk, 5.9 [4.3-7.9]) were also associated with increased mortality.


This study proposes evidence-based thresholds for patient-to-caregiver ratios, above which patient safety may be endangered in the ICU. Real-time monitoring of staffing levels and workload is feasible for adjusting caregivers' resources to patients' needs.

[Indexed for MEDLINE]

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