CT Pulmonary Angiogram Clinical Pretest Probability Tool: Impact on Emergency Department Utilization

Currently, CT pulmonary angiogram (CTPA) for evaluating acute pulmonary embolism (PE) in emergency departments (EDs) is overused and with low yields. The goal of this study is to assess the impact of an evidence-based clinical decision support (CDS) tool, aimed at optimizing appropriate use of CTPA for evaluating PE.

The study was performed at EDs in a large health care system and included nine academic and community hospitals. The primary outcome was the percent difference in utilization (number of CTPAs performed per number of ED visits) and secondary outcome was yield (percentage of CTPAs positive for acute PE), comparing 12 months before (June 1, 2021, to May 31, 2022) versus 12 months after (June 1, 2022, to May 31, 2023) a systemwide implementation of the CDS. Univariate and multivariable analyses using logistic regression were performed to assess factors associated with diagnosis of acute PE. Statistical process control charts were used to assess monthly trends in utilization and yield.

Among 931,677 visits to EDs, 28,101 CTPAs were performed on 24,675 patients. In all, 14,825 CTPAs were performed among 455,038 visits (3.26%) pre-intervention and 13,276 among 476,639 visits (2.79%) postintervention, a 14.51% relative decrease in CTPA utilization (χ², P < .001). CTPA yield remained unchanged (1,371 of 14,825 = 9.25% pre- versus 1,184 of 13,276 = 8.92% postintervention; χ², P = .34). Patients with coronavirus disease of 2019 diagnosis before CTPA had higher probability of acute PE. Statistical process control charts demonstrated seasonal variation in utilization (Friedman test, P = .047).

Implementing a CDS based on validated decision rules was associated with a significant reduction in CTPA utilization. The change was immediate and sustained for 12 months postintervention.