123 Racial and Ethnic Disparities in Diagnostic Imaging Utilization During Adult Emergency Department Visits in the United States, 2005-2014

To compare the use of medical imaging (x-ray [XR], computed tomography [CT], ultrasound [US], and magnetic resonance imaging [MRI]) in the emergency department (ED) between adult patients of different racial and ethnic groups in the United States from 2005 to 2014. Racial and ethnic disparities have been described in ED care; however, the differential use of imaging—a key driver of resource use in the ED—which should theoretically be race-agnostic, has not been previously described. We performed a multilevel stratified regression analysis of the National Hospital Ambulatory Medical Care Survey ED Subfile (NHAMCS-ED), a nationally representative sample of hospital-based EDs and ED visits. We examined race (white, black, Asian, other) and ethnicity (Hispanic versus non-Hispanic) as the primary exposures for the outcomes of ED medical imaging use (XR, CT, US, MRI, Any Imaging) among adult patients with a listed race/ethnicity in the data source. We controlled for other potential patient-level and facility-level determinants of ED imaging use in our analysis of the odds of receipt of imaging in the ED. Approximately half (48.8%) of the 225,037 adult patient visits in the sample underwent ED medical imaging. 36.1% underwent XR, 16.4% CT, 4.1% US, and 0.8% MRI. White patients received ED medical imaging during 51.3% of their encounters, while black patients received imaging during 43.6% of their encounters, Asians during 50.8%, and Other race during 46% of their encounters. Hispanic patients received imaging in 45.1% of their encounters. As compared to white patients, black patients had a decreased adjusted odds of receiving imaging in the ED (OR= 0.87, 95% CI: 0.85-0.90). This disparity was not evident for Hispanic ethnicity nor the other analyzed racial groups. Comparatively, black patients had a much lower odds of receiving a CT scan (OR=0.78, 95% CI: 0.75-0.81) or MRI (OR=0.74, 95% CI: 0.65-0.85). Interestingly, Hispanic patients had a higher odds of receiving an US (OR=1.46, 95% CI: 1.38-1.56) compared to non-Hispanic white patients. We did not note a large ethnic difference in utilization of other imaging modalities. We observed large racial and ethnic differences with regard to how medical imaging is used in the ED even after controlling for patient and facility-level factors. To what degree this difference is due to underuse of imaging or over-use of imaging differentially by racial and ethnic group warrants further investigation. Nonetheless, we describe in this study substantial disparities in imaging use for black adult patients in the emergency department.