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Who bounces back? Physiologic and other predictors of intensive care unit readmission

Rosenberg, Andrew L. MD; Hofer, Timothy P. MD; Hayward, Rodney A. MD; Strachan, Cathy MSRN; Watts, Charles M. MD

Clinical Investigations

Objective To determine the influence of changes in acute physiology scores (APS) and other patient characteristics on predicting intensive care unit (ICU) readmission.

Design Secondary analysis of a prospective cohort study.

Setting Single large university medical intensive care unit.

Patients A total of 4,684 consecutive admissions from Janu-ary 1, 1994, to April 1, 1998, to the medical ICU.

Interventions None.

Measurements and Main Results  The independent influence of patient characteristics, including daily APS, admission diagnosis, treatment status, and admission location, on ICU readmission was evaluated using logistic regression. After accounting for first ICU admission deaths, 3,310 patients were “at-risk” for ICU readmission and 317 were readmitted (9.6%). Hospital mortality was five times higher (43% vs. 8%;p < .0001), and length of stay was two times longer (16 ± 16 vs. 32 ± 28 days;p < .001) in readmitted patients. Mean discharge APS was significantly higher in the readmitted group compared with the not readmitted group (43 ± 19 vs. 34 ± 18;p > .01). Significant independent predictors of ICU readmission included discharge APS >40 (odds ratio [OR] 2.1; 95% confidence interval [CI] 1.6–2.7;p < .0001), admission to the ICU from a general medicine ward (Floor) (OR 1.9; 95% CI 1.4–2.6;p < .0001), and transfer to the ICU from other hospital (Transfer) (OR 1.7; 95% CI 1.3–2.3;p < .01). The overall model calibration and discrimination were (H-L χ2 = 3.8, df = 8;p = .85) and (receiver operating characteristic 0.67), respectively.

Conclusions Patients readmitted to medical ICUs have significantly higher hospital lengths of stay and mortality. ICU readmissions may be more common among patients who respond poorly to treatment as measured by increased severity of illness at first ICU discharge and failure of prior therapy at another hospital or on a general medicine unit. Tertiary care ICUs may have higher than expected readmission rates and mortalities, even when accounting for severity of illness, if they care for significant numbers of transferred patients.

From the Robert Wood Johnson Clinical Scholars Program (Drs. Rosenberg and Hayward), the Department of Anesthesiology and Critical Care Medicine (Dr. Rosenberg), the Department of Internal Medicine (Drs. Hofer, Hayward, and Watts and Ms. Strachan), and the Ann Arbor Veterans Administration Health Services, Research and Development Department (Drs. Hofer and Hayward), The University of Michigan Health System, Ann Arbor, MI.

These findings may have more generalizable implications to referral centers that treat significant numbers of transferred patients and may have worse than expected readmission rates, costs and, outcomes.

Dr. Rosenberg is supported by a grant from the Robert Wood Johnson Foundation and the Veterans Affairs Administration Health Services Research and Development (HSR&D). Dr. Hofer is a Veterans Administration Health Service Research Career Development Awardee.

© 2001 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins