Emergency department imaging superusers.

To identify and characterize the most frequent users of emergency department (ED) imaging. All patients with at least one ED visit in 2016 across a four-hospital healthcare system were retrospectively identified and their ED imaging utilization characterized. Overall, 126,940 unique patients underwent 187,603 ED visits (mean 1.5 ± 1.7) and a total of 192,142 imaging examinations (mean 1.7 ± 2.7). Fifty-eight percent of patients were imaged (73,672) and underwent a mean 2.6 ± 2.7 exams. When ranked by ED visits, 1.6% (2007) of patients had ≥ 4 ED visits (mean 6.1 ± 5.4). These ED "clinical superusers" accounted for 7.7% (14,409) of total ED visits and underwent 6.8 ± 5.4 imaging examinations, while non-superusers underwent 1.5 ± 2.2 (p < 0.01). When ranked by ED imaging utilization, 12.3% (15,575) of patients underwent ≥ 4 ED imaging examinations and consumed 49.5% (95,053) of all imaging services. A subset of just 1.3% (1608) of ED patients underwent > 10 annual ED examinations (ED "imaging superusers") and accounted for 12.4% (23,787) of all ED imaging services. Only 0.4% (n = 472) of patients were both clinical and imaging superusers. Despite similar ED visits to clinical superusers (6.0 ± 5.6 vs. 6.1 ± 5.4, p = 0.92), imaging superusers underwent significantly more imaging (14.8 ± 4.8 vs. 6.8 ± 5.4 examinations, p < 0.01). Just 12% of ED patients consume 50% of all ED imaging services, and 1.3% consume 12.4%. These ED imaging superusers represent a distinct group from clinical superusers. Prospective identification of this newly described subgroup might permit targeted interventions to control ED imaging volume, restrain costs, and minimize per-patient radiation exposure.