Predictors of Emergency Department Observation Unit Outcomes

Background: Acute decompensated heart failure (adHF) is the cause of approximately one million annual hospital admissions. In some of these, the use of a short-stay Emergency Department Observation Unit (EDOU) decreases 90-day ED revisits, 90-day rehospitalizations, and if subsequent hospitalization is required, results in a shorter length of stay. The purpose of this study was to determine if 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 sodium, creatinine, blood urea nitrogen (BUN), hemoglobin, b-type natriuretic peptide, and initial ED systolic blood pressure. Data was analyzed for ability to predict the requirement of hospital admission after EDOU management. Results: There were 385 patients entered. The mean age was 69.7 years and 50.1% were female. On ED admission chest film, 69.0% had evidence of pulmonary edema. Elevations in creatinine and BUN had statistically significant associations with admission; however, on multivariable analysis, only a BUN >30 mg/dL significantly predicted EDOU management failure and subsequent inpatient admission. Conclusions: Our results demonstrate that a BUN >30 mg/dL is associated with an increased likelihood of admission in patients with acute decompensated HF. This provides the emergency medicine physician with a practical prognostic tool for disposition planning in patients with congestive heart failure.