Eosinopenia as a predictor of unexpected re-admission and mortality after intensive care unit discharge

Predicting unexpected intensive care unit (ICU) re-admission and mortality after critical illness is difficult. This study assessed the associations between eosinopenia on the day of ICU discharge and outcomes after critical illness. This retrospective cohort study involved a total of 1446 critically ill patients who survived their first ICU admission between January 2009 and March 2010 in a multidisciplinary ICU in Western Australia. Eosinopenia was defined as eosinophil count <0.01×109/l and the date of censor for survival was 31 October 2011. Of the 1446 patients included in the study, 106 patients (7.3%) were re-admitted to the ICU during the same hospitalisation and 178 patients died (12.3%) after ICU discharge. Eosinopenia at ICU discharge occurred in 130 patients (9.7%) and was more common among those who were subsequently re-admitted (18.6 vs 8.6%) or died after ICU discharge (22.5 vs 7.5%). Eosinopenia remained associated with ICU re-admission (odds ratio 2.50, 95% confidence interval 1.38-4.50; P=0.002) and post-ICU mortality (hazard ratio 2.65, 95% confidence interval 1.77-3.98; P=0.001) after adjusting for age, gender, nocturnal discharge, neutrophil count at ICU discharge, elective surgical admission, Sequential Organ Failure Assessment scores, Acute Physiology and Chronic Health Evaluation II predicted mortality and chronic medical diseases. Eosinopenia at ICU discharge explained about 8.4% of the variability and was the third most important factor in explaining the variability in survival after ICU discharge. In summary, eosinopenia at ICU discharge was associated with an increased risk of unexpected ICU re-admission and post-ICU mortality.