Patients' Use of Multiple Hospitals in a Major US City: Implications for Population Management.

Understanding how often patients seek care from multiple hospitals is important for care of individuals and populations, but it is not routinely measured because of lack of data. This study used data from a health information exchange (HIE) to measure the frequency with which patients seek care from multiple hospitals. This was a retrospective cohort study (2010-2011) of all patients who sought emergency department (ED) or inpatient care at 6 participating hospitals in Manhattan. The study found that all 6 hospitals shared patients with each of the other hospitals and that 10.0% of all ED visits and 9.1% of all admissions were for patients who had been seen in a different hospital in the past 12 months. Patients are frequently seen by multiple hospitals, which poses a challenge for clinical care and population management. By capturing which patients are seen where and when, HIEs are well suited for facilitating population management.