Risk factors and prognostic predictors of unexpected intensive care unit admission within 3 days after ED discharge

Objective: Our objective was to investigate the risk factors and prognostic predictors of unexpected intensive care unit (ICU) admission within 3 days after emergency department (ED) discharge. Methods: From January 1, 2001, through December 31, 2005, patients admitted to the ICU unexpectedly within 3 days after being discharged from the ED were enrolled. Medical records of these patients were retrospectively reviewed. We categorized each patient's characteristics into dichotomous groups and used the χ² test to identify risk factors for unexpected ICU admission within 3 days after ED discharge. A multiple logistic regression was applied to examine possible independent predictors of poor prognoses. Results: During the study period, 365 321 patients visited our ED; 241(0.07%) were unexpectedly admitted to the ICU within 3 days after being discharged from the ED. Mean patient age was 74.2 ± 16.4 years. The rate of ICU admissions caused by medical error was 0.019% ± 0.004% of all visits and 29.0% ± 5.7% of all unexpected ICU admissions. The overall mortality rate was 19.9% (48/241). Risk factors for unexpected ICU admission within 3 days after discharge from the ED were age of 65 years or older (odds ratio [OR], 5.4; 95% confidence interval [CI], 4.0-7.4), ambulance transport (OR, 5.1; 95% CI, 3.9-6.5), no accompanying family (OR, 3.5; 95% CI, 2.7-4.5), nonambulatory status (OR, 4.2; 95% CI, 2.9-5.0), not living at home (OR, 2.5; 95% CI, 1.9-3.3), Medicaid insurance (OR, 3.6; 95% CI, 2.8-4.7), and emergency stay of more than 24 hours (OR, 4.4; 95% CI, 3.4-5.7). The independent predictors of mortality were age of 65 years or older (OR, 2.4; 95% CI, 1.7-3.6), multiple comorbidities (OR, 4.0; 95% CI, 1.8-8.5), medical error leading to ICU admission (OR, 3.9; 95% CI, 1.8-8.3), and Acute Physiology and Chronic Health Evaluation II score of 20 or higher (OR, 2.9; 95% CI, 1.1-7.8). Conclusions: In our study, the risk factors and prognostic predictors of unexpected ICU admission within 3 days after ED discharge were identified. Based on these risk and prognostic prediction factors, further strategies for decreasing the incidence of serious adverse events of ED-discharged patients can be implemented.