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.
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