Background: Hospital readmissions are common and are viewed as unfavorable. They are commonly used as a measure of quality of care and, in the United States and England, are associated with financial penalties. Readmissions are not the only possible return-to-acute-care metric; patients may also attend emergency departments (ED).

Objective: To assess hospital-level return-to-acute-care metrics using statistical criteria.

Research Design: Patient readmissions and/or ED attendances were aggregated to produce risk-standardized hospital rates. Return-to-acute-care rates at 7, 30, 90, and 365 days were assessed using key statistical properties: (i) variability between hospitals; (ii) the relative contribution of patient and nonpatient factors to variation; and (iii) the statistical power to detect performance differences.

Subjects: We had pseudonymized administrative data on all inpatient hospital admissions and ED attendances in National Health Service hospitals in England between April 2009 and March 2011. Patients with an inpatient stay for chronic obstructive pulmonary disorder or heart failure were eligible for inclusion.

Measures: ED attendances and readmissions for patients discharged from an inpatient stay for chronic obstructive pulmonary disorder or heart failure.

Results: Interhospital variation was greatest for ED attendance; in addition, readmission was more strongly determined by patient characteristics than was ED attendance or both combined. Because of smaller numbers, the statistical power to detect differences in rates at 7 days for any indicator was limited.

Conclusions: Despite the current emphasis on readmissions, we found that ED attendance within 30 days has more desirable statistical properties and therefore the potential to be a useful metric when comparing hospitals.