Readmission to the Intensive Care Unit: Incidence, Risk Factors, Resource Use, and Outcomes. A Retrospective Cohort Study.

RATIONALE

Readmission to the intensive care unit (ICU) is associated with poor clinical outcomes, increased length of ICU and hospital stay, and higher costs. Nevertheless, knowledge of epidemiology of ICU readmissions, risk factors, and attributable outcomes is restricted to developed countries.

OBJECTIVES

To determine the effect of ICU readmissions on in-hospital mortality, determine incidence of ICU readmissions, identify predictors of ICU readmissions and hospital mortality, and compare resource use and outcomes between readmitted and nonreadmitted patients in a developing country.

METHODS

This retrospective single-center cohort study was conducted in a 40-bed, open medical-surgical ICU of a private, tertiary care hospital in São Paulo, Brazil. The Local Ethics Committee at Hospital Israelita Albert Einstein approved the study protocol, and the need for informed consent was waived. All consecutive adult (≥18 yr) patients admitted to the ICU between June 1, 2013 and July 1, 2015 were enrolled in this study.

RESULTS

Comparisons were made between patients readmitted and not readmitted to the ICU. Logistic regression analyses were performed to identify predictors of ICU readmissions and hospital mortality. Out of 5,779 patients admitted to the ICU, 576 (10%) were readmitted to the ICU during the same hospitalization. Compared with nonreadmitted patients, patients readmitted to the ICU were more often men (349 of 576 patients [60.6%] vs. 2,919 of 5,203 patients [56.1%]; P = 0.042), showed a higher (median [interquartile range]) severity of illness (Simplified Acute Physiology III score) at index ICU admission (50 [41-61] vs. 42 [32-54], respectively, for readmitted and nonreadmitted patients; P < 0.001), and were more frequently admitted due to medical reasons (425 of 576 [73.8%] vs. 2,998 of 5,203 [57.6%], respectively, for readmitted and nonreadmitted patients; P < 0.001). Simplified Acute Physiology III score (P < 0.001), ICU admission from the ward (odds ratio [OR], 1.907; 95% confidence interval [CI], 1.463-2.487; P < 0.001), vasopressors need during index ICU stay (OR, 1.391; 95% CI, 1.130-1.713; P = 0.002), and length of ICU stay (P = 0.001) were independent predictors of ICU readmission. After adjusting for severity of illness, ICU readmission (OR, 4.103; 95% CI, 3.226-5.518; P < 0.001), admission source, presence of cancer, use of vasopressors, mechanical ventilation or renal replacement therapy, length of ICU stay, and nighttime ICU discharge were associated with increased risk of in-hospital death.

CONCLUSIONS

Readmissions to the ICU were frequent and strongly related to poor outcomes. The degree to which ICU readmissions are preventable as well as the main causes of preventable ICU readmissions need to be further determined.