The Introduction and Development of the H-index for Imaging Utilizers: A Novel Metric for Quantifying Utilization of Emergency Department Imaging.

OBJECTIVE: The objective was to develop a novel metric for quantifying patient-level utilization of emergency department (ED) imaging. METHODS: Using 2009 to 2015 Truven Health MarketScan commercial claims and encounters database, all ED visits and associated imaging services were identified. To measure imaging resource intensity, total imaging relative value units (RVUs) were calculated for each patient per ED visit. An individual's annual imaging h-index is defined as the largest number, h, such that h ED visits by that individual in a given year is associated with total medical imaging RVUs of a value of at least h. RESULTS: Over 7 years, in a sample of 86,506,362 privately insured individuals (232,919,808 person-years) in all 50 states and the District of Columbia, 38,973,716 ED visits were identified. A total of 9.5% of person-years had one ED visit and 2.7% had two or more (the remainder had none). From 2009 to 2015, the percentage of ED patients undergoing imaging increased from 25.1% to 34.6%. Individuals with two or more ED visits each associated with two or more imaging RVUs (ED imaging h-index ≥ 2) comprised 0.2% of the sample and 1.4% of ED visitors; however, they accounted for 4.0% of ED visits and the use of 18.6% of imaging resources. From 2009 to 2015, imaging resource allocation for such patients increased from 16.5% to 21.0%. CONCLUSIONS: The ED imaging h-index allows identification of patients who undergo significant ED imaging, based on a single-digit patient-specific metric that incorporates both annual ED visit number and medical imaging resource intensity per visit. While ED patients with an ED imaging h-index ≥ 2 represented a minuscule fraction of privately insured individuals, they were associated with one-fifth of all ED imaging resources.