Hospital mortality prediction for intermediate care patients: Assessing the generalizability of the Intermediate Care Unit Severity Score (IMCUSS)

David N Hager; Varshitha Tanykonda; Zeba Noorain; Sarina K Sahetya; Catherine E Simpson; Juan Felipe Lucena; Dale M Needham

doi:10.1016/j.jcrc.2018.05.009

Hospital mortality prediction for intermediate care patients: Assessing the generalizability of the Intermediate Care Unit Severity Score (IMCUSS)

J Crit Care. 2018 Aug:46:94-98. doi: 10.1016/j.jcrc.2018.05.009. Epub 2018 May 19.

Authors

David N Hager¹, Varshitha Tanykonda², Zeba Noorain², Sarina K Sahetya³, Catherine E Simpson⁴, Juan Felipe Lucena⁵, Dale M Needham⁶

Affiliations

¹ Division of Pulmonary & Critical Care Medicine, Department of Medicine, Johns Hopkins University, Baltimore, MD, United States. Electronic address: [email protected].
² Bangalore Medical College and Research Institute, Bangalore, India.
³ Division of Pulmonary & Critical Care Medicine, Department of Medicine, Johns Hopkins University, Baltimore, MD, United States. Electronic address: [email protected].
⁴ Division of Pulmonary & Critical Care Medicine, Department of Medicine, Johns Hopkins University, Baltimore, MD, United States. Electronic address: [email protected].
⁵ Division of Intermediate Care and Hospitalists Unit, Department of Internal Medicine, Clinica Universidad de Navarra, Pamplona, Navarra, Spain. Electronic address: [email protected].
⁶ Division of Pulmonary & Critical Care Medicine, Department of Medicine, Johns Hopkins University, Baltimore, MD, United States; Armstrong Institute for Patient Safety, John Hopkins University, Baltimore, MD, United States; Outcomes After Critical Illness and Surgery (OACIS) Group, Johns Hopkins University, Baltimore, MD, United States; Department of Physical Medicine and Rehabilitation, School of Medicine, Johns Hopkins University, Baltimore, MD, United States. Electronic address: [email protected].

Abstract

Purpose: The Intermediate Care Unit Severity Score (IMCUSS) is an easy to calculate predictor of in-hospital death, and the only such tool developed for patients in the intermediate care setting. We sought to examine its external validity.

Materials and methods: Using data from patients admitted to the intermediate care unit (IMCU) of an urban academic medical center from July to December of 2012, model discrimination and calibration for predicting in-hospital death were assessed using the area under the receiver operating characteristic (AUROC) and the Hosmer-Lemeshow goodness-of-fit chi-squared (HL GOF X²) test, respectively. The standardized mortality ratio (SMR) with 95% confidence intervals (95% CI) was also calculated.

Results: The cohort included data from 628 unique admissions to the IMCU. Overall hospital mortality was 8.3%. The median IMCUSS was 10 (Interquartile Range: 0-16), with 229 (36%) patients having a score of zero. The AUROC for the IMCUSS was 0.72 (95% CI: 0.64-0.78), the HL GOF X² = 30.7 (P < 0.001), and the SMR was 1.22 (95% CI: 0.91-1.60).

Conclusions: The IMCUSS exhibited acceptable discrimination, poor calibration, and underestimated mortality. Other centers should assess the performance of the IMCUSS before adopting its use.

Keywords: Intermediate care; Mortality prediction; Outcome prediction score; Progressive care; Stepdown care.

MeSH terms

Adolescent
Adult
Aged
Area Under Curve
Calibration
Critical Care / statistics & numerical data*
Female
Hospital Mortality*
Humans
Intensive Care Units*
Length of Stay
Male
Middle Aged
Models, Organizational
Outcome Assessment, Health Care
Patient Admission
ROC Curve
Reproducibility of Results
Retrospective Studies
Severity of Illness Index*
Spain
Young Adult

Grants and funding

T32 HL007534/HL/NHLBI NIH HHS/United States