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

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 January 1, 1994, to April 1, 1998, to the medical ICU. Interventions: None. Measurements and Main Results: The independent influence of patient charact eristics, including daily APS, admission diagnosis, treatment status, and a dmission location, on ICU readmission was evaluated using logistic regressi on. After accounting for first ICU admission deaths, 3,310 patients were "a t-risk" far ICU readmission and 317 were readmitted (9.6%). Hospital mortal ity was five times higher (43% vs. 8%; p < .0001), and length of stay was t wo times longer (16 +/- 16 vs. 32 +/- 28 days; p < .001) in readmitted pati ents. Mean discharge APS was significantly higher in the readmitted group c ompared with the not readmitted group (43 +/- 19 vs. 34 +/- 18; p > .01). S ignificant independent predictors of ICU readmission included discharge APS >40 (odds ratio [OR] 2.1; 95% confidence interval [GI] 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 disc rimination were (H-L <chi>2 = 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 se verity of illness at first ICU discharge and failure of prior therapy at an other hospital or an a general medicine unit. Tertiary care ICUs may have h igher than expected readmission rates and martalities, even when accounting for severity of illness, if they care for significant numbers of transferr ed patients.