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West J Emerg Med. 2017 Oct;18(6):1091-1097. doi: 10.5811/westjem.2017.7.34581. Epub 2017 Sep 18.

Knowledge Translation of the PERC Rule for Suspected Pulmonary Embolism: A Blueprint for Reducing the Number of CT Pulmonary Angiograms.

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Hartford Hospital, Department of Emergency Medicine, Hartford, Connecticut.
University of Connecticut School of Medicine, Department of Emergency Medicine, Farmington, Connecticut.
Rabin Medical Center, Department of Emergency Medicine, Petah Tikvah, Israel.
Charlotte Hungerford Hospital, Department of Emergency Medicine, Torrington, Connecticut.
Rutland Regional Medical Center, Department of Emergency Medicine, Rutland, Vermont. University of New Mexico, Department of Emergency Medicine, Albuquerque, New Mexico.
University of Cincinnati College of Medicine, Department of Emergency Medicine, Cincinnati, Ohio.



Computerized decision support decreases the number of computed tomography pulmonary angiograms (CTPA) for pulmonary embolism (PE) ordered in emergency departments, but it is not always well accepted by emergency physicians. We studied a department-endorsed, evidence-based clinical protocol that included the PE rule-out criteria (PERC) rule, multi-modal education using principles of knowledge translation (KT), and clinical decision support embedded in our order entry system, to decrease the number of unnecessary CTPA ordered.


We performed a historically controlled observational before-after study for one year pre- and post-implementation of a departmentally-endorsed protocol. We included patients > 18 in whom providers suspected PE and who did not have a contraindication to CTPA. Providers entered clinical information into a diagnostic pathway via computerized order entry. Prior to protocol implementation, we provided education to ordering providers. The primary outcome measure was the number of CTPA ordered per 1,000 visits one year before vs. after implementation.


CTPA declined from 1,033 scans for 98,028 annual visits (10.53 per 1,000 patient visits (95% CI [9.9-11.2]) to 892 scans for 101,172 annual visits (8.81 per 1,000 patient visits (95% CI [8.3-9.4]) p<0.001. The absolute reduction in PACT ordered was 1.72 per 1,000 visits (a 16% reduction). Patient characteristics were similar for both periods.


Knowledge translation clinical decision support using the PERC rule significantly reduced the number of CTPA ordered.

[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. This project was supported by a grant from Hartford Hospital Medical Staff and by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant UL1 RR025744.

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