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Conditional Survival With Increasing Duration of ICU Admission

An Observational Study of Three Intensive Care Databases

Marshall, Dominic C. MRCP1,2; Hatch, Robert A. FRCA1,2; Gerry, Stephen MSc3; Young, J. Duncan DM1; Watkinson, Peter MD1

doi: 10.1097/CCM.0000000000004082
Clinical Investigation: PDF Only

Objectives: Prolonged admissions to an ICU are associated with high resource utilization and personal cost to the patient. Previous reports suggest increasing length of stay may be associated with poor outcomes. Conditional survival represents the probability of future survival after a defined period of treatment on an ICU providing a description of how prognosis evolves over time. Our objective was to describe conditional survival as length of ICU stay increased.

Design: Retrospective observational cohort study of three large intensive care databases.

Setting: Three intensive care databases, two in the United States (Medical Information Mart for Intensive Care III and electronic ICU) and one in United Kingdom (Post Intensive Care Risk-Adjusted Alerting and Monitoring).

Patients: Index admissions to intensive care for patients 18 years or older.

Interventions: None.

Measurements and Main Results: A total of 11,648, 38,532, and 165,125 index admissions were analyzed from Post Intensive Care Risk-Adjusted Alerting and Monitoring, Medical Information Mart for Intensive Care III and electronic ICU databases respectively. In all three cohorts, conditional survival declined over the first 5–10 days after ICU admission and changed little thereafter. In patients greater than or equal to 75 years old conditional survival continued to decline with increasing length of stay.

Conclusions: After an initial period of 5–10 days, probability of future survival does not decrease with increasing length of stay in unselected patients admitted to ICUs. These findings were consistent between the three populations and suggest that a prolonged admission to an ICU is not a reason for a pessimism in younger patients but may indicate a poor prognosis in the older population.

1Critical care research group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.

2Oxford University Clinical Academic Graduate School, John Radcliffe Hospital, Oxford, United Kingdom.

3Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom.

Drs. Marshall, Young, and Watkinson designed the study. Drs. Marshall and Hatch and Mr. Gerry conducted the analysis. All authors were responsible for interpreting the data and drafting of the article.

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This publication has been made possible through access to a research database that was created with support from the Health Innovation Challenge Fund (HICF-0510-006; WT-094951), a parallel funding partnership between the Department of Health and Wellcome Trust. Access was granted by the owners of the research database, the University of Oxford Critical Care Research Group.

Dr. Young’s institution received funding from Health Innovation Challenge Fund (joint venture of Wellcome Trust and U.K. Department of Health. Dr. Watkinson’s institution received funding from Drayson Health and National Institute for Health Research (NIHR) Biomedical Research Center, Oxford, and he received funding from Drayson Health. Dr. Hatch is funded by an NIHR Academic Clinical Fellowship. Gerry is funded by an NIHR Doctoral Fellowship (DRF-2016-09-073). Dr. Watkinson has developed an electronic observations application for which Drayson Health (now Sensyne Health) has purchased a sole license. The company has a research agreement with the University of Oxford and pay personal fees. No other authors have financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years, nor other relationships or activities that could appear to have influenced the submitted work. Dr. Marshall has disclosed that he does not have any potential conflicts of interest.

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