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Electronic pulmonary embolism clinical decision support and effect on yield of computerized tomographic pulmonary angiography: ePE—A pragmatic prospective cohort study

Abstract Objective Multiple professional societies recommend pre‐test probability (PTP) assessment prior to imaging in the evaluation of patients with suspected pulmonary embolism (PE), however, PTP testing remains uncommon, with imaging occurring frequently and rates of confirmed PE remaining low. The goal of this study was to assess the impact of a clinical decision support tool embedded into the electronic health record to improve the diagnostic yield of computerized tomography pulmonary angiography (CTPA) in suspected patients with PE in the emergency department (ED). Methods Between July 24, 2014 and December 31, 2016, 4 hospitals from a healthcare system embedded an optional electronic clinical decision support system to assist in the diagnosis of pulmonary embolism (ePE). This system employs the Pulmonary Embolism Rule‐out Criteria (PERC) and revised Geneva Score (RGS) in series prior to CT imaging. We compared the diagnostic yield of CTPA) among patients for whom the physician opted to use ePE versus the diagnostic yield of CTPA when ePE was not used. Results During the 2.5‐year study period, 37,288 adult patients were eligible and included for study evaluation. Of eligible patients, 1949 of 37,288 (5.2%) were enrolled by activation of the tool. A total of 16,526 CTPAs were performed system‐wide. When ePE was not engaged, CTPA was positive for PE in 1556 of 15,546 scans for a positive yield of 10.0%. When ePE was used, CTPA identified PE in 211 of 980 scans (21.5% yield) (P < 0.001). Conclusions ePE significantly increased the diagnostic yield of CTPA without missing 30‐day clinically overt PE.

by activation of the tool. A total of 16,526 CTPAs were performed system-wide. When ePE was not engaged, CTPA was positive for PE in 1556 of 15,546 scans for a positive yield of 10.0%. When ePE was used, CTPA identified PE in 211 of 980 scans (21.5% yield) (P < 0.001).
Conclusions: ePE significantly increased the diagnostic yield of CTPA without missing 30-day clinically overt PE.

K E Y W O R D S
electronic clinical decision, emergency department, pulmonary embolism INTRODUCTION

Background
Acute pulmonary embolism (PE) is diagnosed in ∼340,000 patients each year in the United States. However, PE is suspected much more frequently, and only ∼10% of all suspected cases of acute PE lead to the diagnosis. [1][2][3][4] Although PE is a diagnosis that is frequently considered among patients presenting to the emergency department (ED), the diagnostic yield (or rate of imaging positive for PE) of pulmonary vasculature imaging is low. 5 Multiple professional societies, including the American College of Chest Physicians, European Society of Cardiology, and the American College of Emergency Physicians, recommend formal assessment of pre-test probability (PTP) for PE followed by laboratory testing or imaging based on PTP risk estimate for patients suspected of PE. [6][7][8] This strategic recommendation reduces the number of patients who will undergo imaging tests by ruling out the disease on the basis of PTP and laboratory results in selected patients. This has the ultimate effect of reducing net radiation exposure in this cohort of patients, reducing direct and indirect costs, and reducing false-positive results in a low PTP cohort. 9

Importance
The two-and three-tiered Wells Criteria, the Revised Geneva Score to PE diagnostic strategies to the ED physician. [9][10][11][12][13][14][15][16][17][18] This effort has been shown to reduce nonadherence to PTP assessment, decrease advanced imaging use, and improve the diagnostic yield of computerized tomography pulmonary angiography (CTPA). [10][11][12][13][14] This effort may have been limited by the requirement for subjective components in these scores including, by the history of derivation and validation of the scores occurring at academic medical centers, and by concern regarding generalizability of the results to community practice settings.

Goals of this investigation
The goal of this study was to assess the impact of a CDS tool embedded into the EHR to improve the diagnostic yield of CTPA in suspected patients with PE in the ED.

Study design and setting
In this prospective cohort study, we report the results of an electronic CDS (eCDS) embedded in the clinical workflow of an integrated healthcare system. After developing this system, we used the ED's desktop computers to implement the PERC and RGS in series to assess PTP for PE. We compare the diagnostic yield of CTPA among patients for whom the treating physician opted to use eCDS with that of treating physicians that did not.
This study was conducted in an integrated community hospital system within 4 EDs with a combined annual ED census of >165,000 patient visits. In this experiment, ePE was integrated into the shared EHR at 3 suburban/rural hospitals and 1 tertiary-referral level 1 trauma center. We compared patients in which ePE was used with those in which ePE was not used. Data were collected from July 24, 2014 to December 31, 2016.

Intervention
Our novel desktop application, electronic pulmonary embolism (ePE), was engineered to implement a consistent, clinical diagnostic algorithm among patients presenting to the ED who were suspected of having pulmonary embolism. The ePE tool was built by our hospital system through a collaboration of emergency physicians, internal medicine physicians with clinical focus on thrombosis, and informatics experts and was based on professional society guidelines ( Figure 1

Selection of participants
All patients age >17 years with suspected PE, as determined by the treating emergency physician through the order for a D-dimer, CTPA, V/Q scan, or activation of the tool, were included for evaluation.
Demographics of included patients are listed in Table 1. Patients were excluded if they were age ≤17 years, pregnant at the time of ED evaluation, or prisoners.

Analysis
All patients for whom the treating physician opted to use the tool were enrolled and their data were prospectively collected. Data from the ePE tool were stored on a secured research server within the institutional firewall. It was decided a priori that all patients for whom the tool was initiated would have all their data, including outcomes, collected in an intention to treat model regardless of whether the tool was run to completion. Patients with suspected PE that did not have ePE used or available had their data collected retrospectively from the hospitals electronic data warehouse (EDW) using standard query techniques by using ICD-9/10, previously validated natural language processing tool for VTE outcomes, and CPT codes. A 30-day follow up was performed using validated methods to determine missed PE. 10 For the primary outcome, incidence of PE on CTPA, we assumed an increase of ∼7%. We planned to enroll a minimum of 650 patients with a CTPA to demonstrate a significant difference with a 5% margin of error and 95% confidence interval (CI). All tests were computed using Student's t-test, and corresponding methods were used to create the confidence intervals on the means and differences of means. Logistic regression was performed in the subset of patients with CTPA (Table 3). Both sample sizes were large enough that the results will be approximately correct even in the cases where the data indicates a non-normal population.
The study was performed according to STROBE guidelines. The Intermountain institutional review board approved the study with a waiver of informed consent (IRB 1024529).

RESULTS
During the 2.

LIMITATIONS
Given that ePE was used in only 5.2% of possible ED encounters, selection bias cannot be excluded. If physicians chose to use the tool in higher risk patients, this could account for the higher incidence of PE with ePE use. It should be noted, however, that regardless of physicianinitiated usage of ePE, all physicians were visually notified of tool availability on ordering any testing for PE.
We cannot rule out that in some instances where the ePE tool was not used, physicians were ordering D-dimer for reasons other than concern for PE (such as disseminated intravascular coagulation, deep vein thrombosis, etc). We believe that the overall rate of D-dimer ordering for alternative etiologies in the ED is low and unlikely to influence our conclusions.
Although patients in our non-tool use cohort may have had PE suspected with no testing done (ie, PERC negative or clinician gestalt) and would not have been captured in our analysis, this would not affect We cannot refute the possibility that we did not capture PE diagnosed within 30 days if a patient presented to a hospital outside our system.

DISCUSSION
The use of an electronic pulmonary embolism CDS tool appears to be associated with reduced CTPA use and improved CTPA diagnostic yield. 9,[11][12][13][14][15][16][17] Our results are consistent with these observations. ePE appears safe given that we did not observe any 30-day PE events among patients for which ePE recommended no further assessment.
No PE was diagnosed when a physician rejected the ePE recommendation and performed CTPA in the setting of a negative PERC or negative D-dimer. However, in patients that were PERC-positive and D-dimer was recommended based on an RGS <11, but deferred by the physician, there was a high rate of PE diagnosis (39%). Reasons for disagreement were collected during tool use, and in 88% of cases, the D-dimer was bypassed due to "recent surgery and D-dimer unlikely to be nega-  PAMA compliance will affect all EDs in the near future, and having an embedded eCDS will ensure appropriate compliance and reimbursement. We believe that ePE will both improve diagnostic yield of CTPA and assure PAMA compliance. We propose that implementation of this eCDS in our EHR system-wide would improve the diagnostic yield for CTPA among patients suspected of PE without increasing the rate of missed diagnoses. Further studies are needed to compare eCDS formats across different healthcare systems as well as focus on optimal eCDS implementation to improve eCDS use.
In our integrated 4-hospital healthcare system, ePE tool use was associated with a significantly higher diagnostic yield of PE on CTPA compared with a combination of non-ePE usage without missed 30-day clinically overt PE.

AUTHOR CONTRIBUTIONS
JRB, CK, SMS, SCW, CGE, PH, and TLA were responsible for manuscript drafts. AMB, JRJ, and JFL were responsible for statistical analysis. All authors assisted in manuscript editing. CK was responsible for journal submission and final responsibility.