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The Stability and Workload Index for Transfer score predicts unplanned intensive care unit patient readmission: Initial development and validation*

Gajic, Ognjen MD; Malinchoc, Michael PhD; Comfere, Thomas B. MD; Harris, Marcelline R. RN, PhD; Achouiti, Ahmed MD; Yilmaz, Murat MD; Schultz, Marcus J. MD; Hubmayr, Rolf D. MD; Afessa, Bekele MD; Farmer, J Christopher MD

doi: 10.1097/CCM.0B013E318164E3B0
Feature Articles

Objective: Unplanned readmission of hospitalized patients to an intensive care unit (ICU) is associated with a worse outcome, but our ability to identify who is likely to deteriorate after ICU dismissal is limited. The objective of this study is to develop and validate a numerical index, named the Stability and Workload Index for Transfer, to predict ICU readmission.

Design: In this prospective cohort study, risk factors for ICU readmission were identified from a broad range of patients’ admission and discharge characteristics, specific ICU interventions, and in-patient workload measurements. The prediction score was validated in two independent ICUs.

Setting: One medical and one mixed medical-surgical ICU in two tertiary centers.

Patients: Consecutive patients requiring >24 hrs of ICU care.

Interventions: None.

Measurements: Unplanned ICU readmission or unexpected death following ICU dismissal.

Results: In a derivation cohort of 1,131 medical ICU patients, 100 patients had unplanned readmissions, and five died unexpectedly in the hospital following ICU discharge. Predictors of readmission/unexpected death identified in a logistic regression analysis were ICU admission source, ICU length of stay, and day of discharge neurologic (Glasgow Coma Scale) and respiratory (hypoxemia, hypercapnia, or nursing requirements for complex respiratory care) impairment. The Stability and Workload Index for Transfer score predicted readmission more precisely (area under the curve [AUC], 0.75; 95% confidence interval [CI], 0.70–0.80) than the day of discharge Acute Physiology and Chronic Health Evaluation III score (AUC, 0.62; 95% CI, 0.56–0.68). In the two validation cohorts, the Stability and Workload Index for Transfer score predicted readmission similarly in a North American medical ICU (AUC, 0.74; 95% CI, 0.67–0.80) and a European medical-surgical ICU (AUC, 0.70; 95% CI, 0.64–0.76), but was less well calibrated in the medical-surgical ICU.

Conclusion: The Stability and Workload Index for Transfer score is derived from information readily available at the time of ICU dismissal and acceptably predicts ICU readmission. It is not known if discharge decisions based on this prediction score will decrease the number of ICU readmissions and/or improve outcome.

From the Department of Internal Medicine and the Mayo Epidemiology and Translational Research in Intensive Care Program (OG, TBC, MY, RDH, BA, JCF), and the Departments of Health Sciences Research (MM, MRH) and Nursing (MRH), Mayo Clinic College of Medicine, Rochester, MN; and The Department of Intensive Care Medicine, University of Amsterdam, Amsterdam, Netherlands (AA, MJS).

Supported, in part, by National Heart, Lung, and Blood Institute grant K23 HL78743–01A1 and the Mayo Clinic.

The authors have not disclosed any potential conflicts of interest.

For information regarding this article, E-mail: gajic.ognjen@mayo.edu

© 2008 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins