Interhospital transfers from U.S. emergency departments: implications for resource utilization, patient safety, and regionalization.

OBJECTIVES: The authors sought to describe the demographic and clinical characteristics of interhospital transfers from U.S. emergency departments (EDs) along with the primary reasons for transfers.
METHODS: This was a retrospective, cross-sectional analysis of the 1997 through 2009 National Hospital Ambulatory Medical Care Survey (NHAMCS). Visit-level characteristics were compared for patients who were transferred, admitted, or discharged. Additionally, data on primary reason for transfer for available years (2005 through 2008) were reviewed. Weighted analyses produced nationally representative estimates.
RESULTS: During this time period, 1.8% (95% confidence interval [CI] = 1.7% to 2.0%) of ED patients were transferred to other hospitals. Compared to visits resulting in admission, those resulting in transfer were more likely to involve patients who were <18 years old (18% vs. 7.9%), male (53% vs. 46%), with Medicaid (22% vs. 16%) or self-payment (15% vs. 8.2%) as a primary expected source of payment, having a visit related to injury (40% vs. 19%), and from a nonurban ED (29% vs. 15%). Among transferred patients, 28% (95% CI = 27% to 30%) received four to six diagnostic tests, and 31% (95% CI = 29% to 34%) received more than six diagnostic tests prior to transfer; 52% (95% CI = 50% to 54%) had diagnostic imaging, and 17% (95% CI = 16% to 19%) had cross-sectional imaging. Of the patients transferred from 2005 through 2008, 47% (95% CI = 43% to 53%) were transferred for a higher level of care, and 29% (95% CI = 26% to 35%) were transferred for psychiatric care.
CONCLUSIONS: Transfer of ED patients was relatively rare, but was more common among specific, potentially high-risk populations. Diagnostic testing, including advanced imaging, was common prior to transfer. A majority of transfers were for reasons indicating limited resources or expertise at the referring facility.