Predictors of emergency department observation unit outcomes

Background: Acute decompensated heart failure (adHF) is the cause of approximately 1 million annual hospital admissions. In some of these, the use of a short-stay emergency department observation unit (EDOU) decreases 90-day ED revisits and 90-day rehospitalizations and, if subsequent hospitalization is required, results in shorter stays. Objectives: To determine whether laboratory and clinical parameters, available at ED arrival, predict successful EDOU discharge. Methods: This was a 19-month retrospective analysis of adHF EDOU admissions. Details of medical history, clinical course, patient management, laboratory data, and disposition destination were gathered through review of electronic medical records. Recorded laboratory data included measurements of sodium, creatinine, blood urea nitrogen (BUN), hemoglobin, b-type natriuretic peptide, and initial ED systolic blood pressure. Data were analyzed for ability to predict the requirement of hospital admission after EDOU management. Results: There were 385 patients were enrolled. The mean (+/- standard deviation) age was 69.7 (+/- 13.6) years, and 50.1% were female. On ED admission chest radiograph, 69.0% had evidence of pulmonary edema. Elevations in creatinine and BUN levels had statistically significant associations with admission; however, on multivariable analysis, only a BUN value > 30 mg/dL significantly predicted EDOU management failure, and subsequent inpatient admission. Conclusions: These results demonstrate that a BUN level > 30 mg/dL is associated with an increased likelihood of admission in patients with adHF. This provides the emergency physician with a practical prognostic tool for disposition planning in congestive heart failure patients.