P113: Variability in utilization and diagnostic yield of computed tomography (CT) scans for pulmonary embolism among emergency physicians

Abstract

Introduction: Current data on utilization of CT imaging point to a trend of increasing overutilization of CT Angiography for the diagnosis of pulmonary embolism (CTPA) over time. Multiple educational and institution-wide interventions addressing this overutilization have been proposed, implemented and evaluated, with mixed results in terms of long-term impact on physician ordering behaviour. The objective of this study is to examine the inter-physician variability in ordering rates and diagnostic yield of CTPA, under a working hypothesis that a small number of physicians are responsible for a disproportionately high number of CTPA ordered in the ED. Methods: Data was collected on all CTPA studies ordered by ED physicians at two very high volume community hospitals and an affiliated urgent care centre during the 2-year period between January 1, 2016 and December 31, 2017. Analysis was limited to those ED physicians who had a total of greater than 500 ED visits over the course of the 2-year period. For each physician, two calculations were made: 1) CT PE ordering rate (total number of CTPA ordered divided by the total number of ED visits), and 2) CTPA diagnostic yield (total number of CTPA positive for PE divided by the total number CTPA ordered). Additional analysis was carried out in order to identify the highest orderers of CTPA and their diagnostic yield. Results: A total of 2,789 CTPA were ordered by 84 physicians for 461,045 total ED visits. Preliminary results show a great deal of variation in ordering rates, ranging from 0.9 to 22.2 CTPA per 1000 ED visit (median = 4.8, IQR = 4.5). Similarly, there was high variation in CT PE yield, ranging from 0% to 50% (median = 9.6%, IQR = 13.1%). Those physicians in the top quartile for ordering rate had a lower mean diagnostic yield, when compared to the lower quartiles (8.9% when compared to 11.5%, 11.9% and 18.2% for the physicians in the third, second, and first quartile respectively). Conclusion: The findings of this study indicate a wide degree of variability in CTPA ordering patterns and diagnostic yield among physicians working within the same clinical environment. There is some suggestion that those physicians who order disproportionately higher numbers of CTPAs have lower diagnostic yields. However, the more interesting lessons from this initial study center on the challenges in creating an audit-and-feedback program targeting CTPA ‘overutilizers’.