Evaluation of pulmonary embolism in the emergency department and consistency with a national quality measure: quantifying the opportunity for improvement

Deployment of a human-centred clinical decision support system for pulmonary embolism: evaluation of impact on quality of diagnostic decisions

Pulmonary embolism (PE) is a serious condition that presents a diagnostic challenge for which diagnostic errors often happen. The literature suggests that a gap remains between PE diagnostic guidelines and adherence in healthcare practice. While system-level decision support tools exist, the clinical impact of a human-centred design (HCD) approach of PE diagnostic tool design is unknown.

DESIGN

Before-after (with a preintervention period as non-concurrent control) design study.

SETTING

Inpatient units at two tertiary care hospitals.

PARTICIPANTS

General internal medicine physicians and their patients who underwent PE workups.

INTERVENTION

After a 6-month preintervention period, a clinical decision support system (CDSS) for diagnosis of PE was deployed and evaluated over 6 months. A CDSS technical testing phase separated the two time periods.

MEASUREMENTS

PE workups were identified in both the preintervention and CDSS intervention phases, and data were collected from medical charts. Physician reviewers assessed workup summaries (blinded to the study period) to determine adherence to evidence-based recommendations. Adherence to recommendations was quantified with a score ranging from 0 to 1.0 (the primary study outcome). Diagnostic tests ordered for PE workups were the secondary outcomes of interest.

RESULTS

Overall adherence to diagnostic pathways was 0.63 in the CDSS intervention phase versus 0.60 in the preintervention phase (p=0.18), with fewer workups in the CDSS intervention phase having very low adherence scores. Further, adherence was significantly higher when PE workups included the Wells prediction rule (median adherence score=0.76 vs 0.59, p=0.002). This difference was even more pronounced when the analysis was limited to the CDSS intervention phase only (median adherence score=0.80 when Wells was used vs 0.60 when Wells was not used, p=0.001). For secondary outcomes, using both the D-dimer blood test (42.9% vs 55.7%, p=0.014) and CT pulmonary angiogram imaging (61.9% vs 75.4%, p=0.005) was lower during the CDSS intervention phase.

CONCLUSION

A clinical decision support intervention with an HCD improves some aspects of the diagnostic decision, such as the selection of diagnostic tests and the use of the Wells probabilistic prediction rule for PE.

Diagnostic Blood Biomarkers for Acute Pulmonary Embolism: A Systematic Review

(1) Background: The current diagnostic algorithm for acute pulmonary embolism (PE) is associated with the overuse of CT pulmonary angiography (CTPA). An additional highly specific blood test could potentially lower the proportion of patients with suspected PE that require CTPA. The aim was to summarize the literature on the diagnostic performance of biomarkers of patients admitted to an emergency department with suspected acute PE. (2) Methods: Medline and Embase databases were searched from 1995 to the present. The study selection process, data extraction, and risk of bias assessment were conducted by two reviewers. Eligibility criteria accepted all blood biomarkers except D-dimer, and CTPA was used as the reference standard. Qualitative data synthesis was performed. (3) Results: Of the 8448 identified records, only 6 were included. Eight blood biomarkers were identified, of which, three were investigated in two separate studies. Red distribution width and mean platelet volume were reported to have a specificity of ≥ 90% in one study, although these findings were not confirmed by other studies. The majority of the studies contained a high risk of selection bias. (4) Conclusions: The modest findings and the uncertain validity of the included studies suggest that none of the biomarkers identified in this systematic review have the potential to improve the current diagnostic algorithm for acute PE by reducing the overuse of CTPA.

How Tasmanian Emergency Departments 'Choose Wisely' When Investigating Suspected Pulmonary Embolism

Overuse of computed tomography pulmonary angiograms (CTPAs) for diagnosis of pulmonary embolism (PE) has been recognised as an issue for over ten years, with Choosing Wisely Australia recommending that CTPAs only be ordered if indicated by a clinical practice guideline (CPG). This study aimed to explore the use of evidence-based practice within regional Tasmanian emergency departments in relation to CTPA orders by determining whether CTPAs were ordered in accordance with validated CPGs. We conducted a retrospective medical record review of all patients who underwent CTPA across all public emergency departments in Tasmania between 1 August 2018 and 31 December 2019 inclusive. Data from 2758 CTPAs across four emergency departments were included. PE was reported in 343 (12.4%) of CTPAs conducted, with yield ranging from 8.2% to 16.1% between the four sites. Overall, 52.1% of participants had neither a CPG documented, nor a D-dimer conducted before their scan. A CPG was documented before 11.8% of scans, while D-dimer was conducted before 43% of CTPAs. The findings presented in this study indicate that Tasmanian emergency departments are not consistently 'Choosing Wisely' when investigating PE. Further research is required to identify explanations for these findings.

Implementation of the YEARS algorithm to optimise pulmonary embolism diagnostic workup in the emergency department

BACKGROUND

Excessive use of CT pulmonary angiography (CTPA) to investigate pulmonary embolism (PE) in the emergency department (ED) contributes to adverse patient outcomes. Non-invasive D-dimer testing, in the context of a clinical algorithm, may help decrease unnecessary imaging but this has not been widely implemented in Canadian EDs.

AIM

To improve the diagnostic yield of CTPA for PE by 5% (absolute) within 12 months of implementing the YEARS algorithm.

MEASURES AND DESIGN

Single centre study of all ED patients >18 years investigated for PE with D-dimer and/or CTPA between February 2021 and January 2022. Primary and secondary outcomes were the diagnostic yield of CTPA and frequency of CTPA ordered compared with baseline. Process measures included the percentage of D-dimer tests ordered with CTPA and CTPAs ordered with D-dimers <500 µg/L Fibrinogen Equivalent Units (FEU). The balancing measure was the number of PEs identified on CTPA within 30 days of index visit. Multidisciplinary stakeholders developed plan- do-study-act cycles based on the YEARS algorithm.

RESULTS

Over 12 months, 2695 patients were investigated for PE, of which 942 had a CTPA. Compared with baseline, the CTPA yield increased by 2.9% (12.6% vs 15.5%, 95% CI -0.06% to 5.9%) and the proportion of patients that underwent CTPA decreased by 11.4% (46.4% vs 35%, 95% CI -14.1% to -8.8%). The percentage of CTPAs ordered with a D-dimer increased by 26.3% (30.7% vs 57%, 95% CI 22.2% 30.3%) and there were two missed PE (2/2695, 0.07%).

IMPACT

Implementing the YEARS criteria may safely improve the diagnostic yield of CTPAs and reduce the number of CTPAs completed without an associated increase in missed clinically significant PEs. This project provides a model for optimising the use of CTPA in the ED.

ACR Appropriateness Criteria® Suspected Pulmonary Embolism: 2022 Update

Pulmonary embolism (PE) remains a common and important clinical condition that cannot be accurately diagnosed on the basis of signs, symptoms, and history alone. The diagnosis of PE has been facilitated by technical advancements and multidetector CT pulmonary angiography, which is the major diagnostic modality currently used. Ventilation and perfusion scans remain largely accurate and useful in certain settings. MR angiography can be useful in some clinical scenarios and lower-extremity ultrasound can substitute by demonstrating deep vein thrombosis; however, if negative, further studies to exclude PE are indicated. In all cases, correlation with the clinical status, particularly with risk factors, improves not only the accuracy of diagnostic imaging but also overall utilization. Other diagnostic tests have limited roles. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Clinical value of deep vein thrombosis density on pre-contrast and post-contrast lower-extremity CT for prediction of pulmonary thromboembolism

Background

There was a lack of studies assessing the relationship between deep vein thrombosis (DVT) Hounsfield unit (HU) density and pulmonary thromboembolism (PTE).

Purpose

To evaluate the clinical value of DVT density measured on pre- and post-contrast lower-extremity computed tomography (CT) for the prediction of PTE.

Material and Methods

From 2017 to 2021, patients who underwent pulmonary CT angiography within one week after diagnosis of DVT on lower-extremity CT were included in this retrospective study. Then, the patients without PTE were included in “DVT group” and those with both DVT and PTE were included in the “DVT-PTE group.” The DVT HU density was measured by drawing free-hand region of interests (ROIs) within the thrombus at the most proximal filling defect level. A receiver operating characteristic (ROC) analysis was used to evaluate the predictive value of DVT density for the risk of PTE.

Results

This study included a total of 94 patients (DVT group: n=56; DVT-PTE group: m=38). DVT density was significantly higher in the DVT-PTE group than the DVT group in both pre-contrast (53.5 ± 6.2 HU vs. 44.1 ± 7.9 HU; P < 0.001) and post-contrast CT (67.0 ± 8.6 HU vs. 57.1 ± 10.6 HU; P < 0.001). ROC analysis revealed that the area under curve, sensitivity, and specificity for predicting the risk of PTE were 0.739, 71.1%, and 64.2%, respectively, at a DVT density cutoff of 48.2 HU on pre-contrast CT and were 0.779, 73.7%, and 69.6% at a DVT density cutoff of 61.8 HU on post-contrast CT.

Conclusion

The DVT density on both pre- and post-contrast CT could be a predictive factor of PTE.

Use of Computed Tomography Pulmonary Angiography in Emergency Departments: A Literature Review

Computed tomography pulmonary angiography (CTPA) has become the most widely used technique for diagnosis or exclusion of a pulmonary embolism (PE). It has been suggested that overuse of this imaging type may be prevalent, especially in emergency departments (EDs). The purpose of this literature review was to explore the use of CTPAs in EDs worldwide. A review following PRISMA guidelines was completed, with research published between September 2010 and August 2020 included. Five key topics emerged: use of CTPAs; explanations for overuse; use of D-dimer; variability in ordering practices between clinicians; and strategies to reduce overuse. This review found that CTPAs continue to be overused in EDs, leading to superfluous risks to patients. Published studies identify that while clinical practice guidelines (CPGs) have a strong effect on reducing unnecessary CTPAs with no significantly increased risk of missed diagnosis, the adoption of these tools by ED clinicians has remained low. This literature review highlights the need for further research into why CTPAs continue to be overused within EDs and why clinicians are hesitant to use CPGs in the clinical setting. Moreover, investigations into other potential strategies that may combat the overuse of this diagnostic tool are essential to reduce potential harm.

Development and validation of a prediction model to estimate risk of acute pulmonary embolism in deep vein thrombosis patients

Venous thromboembolism (VTE), clinically presenting as deep vein thrombosis (DVT) or pulmonary embolism (PE). Not all DVT patients carry the same risk of developing acute pulmonary embolism (APE). To develop and validate a prediction model to estimate risk of APE in DVT patients combined with past medical history, clinical symptoms, physical signs, and the sign of the electrocardiogram. We analyzed data from a retrospective cohort of patients who were diagnosed as symptomatic VTE from 2013 to 2018 (n = 1582). Among them, 122 patients were excluded. All enrolled patients confirmed by pulmonary angiography or computed tomography pulmonary angiography (CTPA) and compression venous ultrasonography. Using the LASSO and logistics regression, we derived a predictive model with 16 candidate variables to predict the risk of APE and completed internal validation. Overall, 52.9% patients had DVT + APE (773 vs 1460), 47.1% patients only had DVT (687 vs 1460). The APE risk prediction model included one pre-existing disease or condition (respiratory failure), one risk factors (infection), three symptoms (dyspnea, hemoptysis and syncope), five signs (skin cold clammy, tachycardia, diminished respiration, pulmonary rales and accentuation/splitting of P₂), and six ECG indicators (S_IQ_IIIT_III, right axis deviation, left axis deviation, S₁S₂S₃, T wave inversion and Q/q wave), of which all were positively associated with APE. The ROC curves of the model showed AUC of 0.79 (95% CI, 0.77–0.82) and 0.80 (95% CI, 0.76–0.84) in the training set and testing set. The model showed good predictive accuracy (calibration slope, 0.83 and Brier score, 0.18). Based on a retrospective single-center population study, we developed a novel prediction model to identify patients with different risks for APE in DVT patients, which may be useful for quickly estimating the probability of APE before obtaining definitive test results and speeding up emergency management processes.

Pulmonary embolism after a long-haul flight

The relation between long-haul flights (LHF) and venous thromboembolic disease is well established. Nonetheless, the incidence of pulmonary embolisms after these flights is probably underestimated because of the difficulties in case ascertainment. Reunion Island appears to present the ideal geographic conditions for accurately assessing this incidence. We aimed to assess the incidence of pulmonary embolisms in people who had recently taken a LHF to Reunion Island. We conducted a retrospective multi-center descriptive study and included all cases of pulmonary embolisms diagnosed between January 1, 2015, and January 30, 2017 (according to the hospitals' discharge summary database) in the island's four public hospitals within 30 days after taking an LHF to Reunion. We took different delays of diagnosis to calculate the incidence. We have considered the time to diagnosis at 1 month as significant according to the time applied in the Geneva score for risk factors. The study included 45 patients landing on Reunion over a 2-year period. The total number of passengers arriving by LHF during this period was 1,223,001. The incidence of pulmonary embolism after an LHF was thus calculated at 36.8 per million travelers at 1 month. The incidence for PE diagnosed, after 15 days was 29.4 per million travelers, and after 7 days, it was 21.9 per million travelers. The male/female ratio was 0.67. The mean interval between the flight and symptom onset was 7 days. In our population, the incidence of pulmonary embolisms after LHFs in our study is clearly higher than that reported in the literature (36.8 vs 4.8). Our exhaustive data collection probably explains this difference. A case-control study appears necessary to analyze the risk factors for pulmonary embolism after a LHF.

Most emergency department patients meeting sepsis criteria are not diagnosed with sepsis at discharge

OBJECTIVES

Effective sepsis resuscitation depends on useful criteria for prompt identification of eligible patients. These criteria should reliably predict a discharge diagnosis of sepsis, ensuring that interventions are triggered for those who need it while avoiding potentially harmful interventions in those who do not. We sought to determine the proportion of patients meeting sepsis criteria in the emergency department (ED) that was ultimately diagnosed with sepsis and to quantify the subset of nonseptic patients with risk factors for harm from fluid resuscitation.

METHODS

This retrospective cohort study of adult ED patients at a tertiary academic medical center included vital signs and laboratory results from the first 6 hours, plus administration of intravenous antibiotics, to determine if patients met 2016 Sepsis-3 consensus criteria. If these patients also had hypotension and lactic acidosis, we categorized them as Sepsis-3 plus shock. We used discharge ICD-9 codes to determine if patients were ultimately diagnosed with sepsis.

RESULTS

Over 8 years, 3,121 ED patients met 2016 Sepsis-3 criteria in the first 6 hours. Of these, only 25% and 48% met explicit and implicit criteria for a discharge diagnosis of sepsis. Of 1,032 patients with Sepsis-3 plus shock, 48% and 62% met explicit and implicit criteria. Overall, 60% to 75% of ED patients meeting Sepsis-3 criteria with or without shock did not receive a sepsis discharge diagnosis. At least one plausible risk factor for harm from large-volume fluid resuscitation was identified among 19% to 36% of patients meeting sepsis criteria in the ED but not ultimately diagnosed with sepsis at discharge.

CONCLUSIONS

Most patients meeting sepsis criteria in the ED were not diagnosed with sepsis at discharge. Urgent treatment bundles triggered by consensus criteria in the early phase of ED care may be administered to several patients without sepsis, potentially exposing some to interventions of uncertain benefit and possible harm.

Added value of hyperdense lumen sign in prediction of acute central and peripheral pulmonary embolism on non-contrast CT chest

Background

Pulmonary embolism (PE) is a common condition with considerable morbidity and mortality; it is more often diagnosed post-mortem by pathologists than in vivo by clinicians. Prompt and accurate diagnosis is difficult because PE may be clinically silent, the symptoms are vague and nonspecific, and in addition, there is no definitive, non-invasive diagnostic test to establish its diagnosis. The aim of this study is to assess the reliability of detection of acute central and peripheral pulmonary embolism (PE) on non-contrast CT especially when no possible alternative is available as in allergic cases or emergency, patients with history of renal disease, or in cases where PE is not the leading diagnosis. CT pulmonary angiography study served as our gold standard.

Results

Eighty adult patients were included in our study; 44 were females and 36 males most of which were complaining of dyspnea and chest pain. Acute central pulmonary embolism was confirmed by CTPA. They all underwent a pre-contrast study just prior to the CTPA. Presence of high attenuation emboli in any of the main pulmonary vessels was our key for diagnosis of acute embolism. Non-contrast CT chest diagnosed 26 of the 47 cases confirmed by CTPA. The hyperdense lumen sign had an overall sensitivity of 55.3%, specificity of 100%, positive predictive value (PPV) of 100%, and negative predictive value of 61.1%. The accuracy of non-contrast CT chest study was evaluated using CTPA as our gold standard.

Conclusion

Non-contrast CT chest is a good indicator in predicting central and peripheral pulmonary embolism, particularly in cases of emergency, those unable to take intravenous contrast for angiography, or in cases where pulmonary embolism is not the leading diagnosis.

Provider Perspectives on the Use of Evidence-based Risk Stratification Tools in the Evaluation of Pulmonary Embolism: A Qualitative Study

OBJECTIVES

Providers often pursue imaging in patients at low risk of pulmonary embolism (PE), resulting in imaging yields <10% and false-positive imaging rates of 10% to 25%. Attempts to curb overtesting have had only modest success and no interventions have used implementation science frameworks. The objective of this study was to identify barriers and facilitators to the adoption of evidence-based diagnostic testing for PE.

METHODS

We conducted semistructured interviews with a purposeful sample of providers. An interview guide was developed using the implementation science frameworks, consolidated framework for implementation research, and theoretical domains framework. Interviews were recorded, transcribed, and analyzed in an iterative process. Emergent themes were identified, discussed, and organized.

RESULTS

We interviewed 23 providers from four hospital systems, and participants were diverse with regard to years in practice and practice setting. Barriers were predominately at the provider level and included lack of knowledge of the tools, particularly misunderstanding of the validated scoring systems in Wells, as well as risk avoidance and need for certainty. Barriers to prior implementation strategies included the perception of a clinical decision support (CDS) tool for PE as adding steps with little value; most participants reported that they overrode CDS interventions because they had already made the decision. All providers identified institution-level strategies as facilitators to use, including endorsed guidelines, audit feedback with peer comparison about imaging yield, and peer pressure.

CONCLUSIONS

This exploration of the use of risk stratification tools in the evaluation of PE found that barriers to use primarily exist at the provider level, whereas facilitators to the use of these tools are largely perceived at the level of the institution. Future efforts to promote the evidence-based diagnosis of PE should be informed by these determinants.

The use of clinical decision rules for pulmonary embolism in the emergency department: a retrospective study

Background

Pulmonary embolism (PE) is a common and life-threatening medical condition with non-specific clinical presentation. Computed tomography pulmonary angiography (CT-PA) has been the diagnostic modality of choice, but its use is not without risks. Clinical decision rules have been established for the use of diagnostic modalities for patients with suspected PE. This study aims to assess the adherence of physicians to the diagnostic algorithms and rules.

Methods

A retrospective observational study examining the utilization of CT-PA in the Emergency Department of King Fahd Hospital of Imam Abdulrahman Bin Faisal University for patients with suspected PE from May 2016 to December 2019. The electronic health records were used to collect the data, including background demographic data, clinical presentation, triage vital signs, D-dimer level (if ordered), risk factors for PE, and the CT-PA findings. The Wells score and pulmonary embolism rule-out (PERC) criteria were calculated retrospectively without knowledge of the results of D-dimer and the CT-PA.

Results

The study involved a total of 353 patients (125 men and 228 women) with a mean age of 46.7 ± 18.4 years. Overall, 200 patients (56.7%) were classified into the “PE unlikely” group and 153 patients (43.3%) in the “PE likely” group as per Wells criteria. Out of all the CT-PA, 119 CT-PA (33.7%) were requested without D-dimer assay (n = 114) or with normal D-dimer level (n = 5) despite being in the “PE unlikely” group. Only 49 patients had negative PERC criteria, of which three patients had PE.

Conclusions

The study revealed that approximately one-third of all CT-PA requests were not adhering to the clinical decision rules with a significant underutilization of D-dimer assay in such patients. To reduce overutilization of imaging, planned interventions to promote the adherence to the current guidelines seem imperative.

Assessment of the Radiology Support, Communication and Alignment Network to Reduce Medical Imaging Overutilization: A Multipractice Cohort Study

PURPOSE

The aim of this study was to determine whether participation in Radiology Support, Communication and Alignment Network (R-SCAN) results in a reduction of inappropriate imaging in a wide range of real-world clinical environments.

METHODS

This quality improvement study used imaging data from 27 US academic and private practices that completed R-SCAN projects between January 25, 2015, and August 8, 2018. Each project consisted of baseline, educational (intervention), and posteducational phases. Baseline and posteducational imaging cases were rated as high, medium, or low value on the basis of validated ACR Appropriateness Criteria®. Four cohorts were generated: a comprehensive cohort that included all eligible practices and three topic-specific cohorts that included practices that completed projects of specific Choosing Wisely topics (pulmonary embolism, adnexal cyst, and low back pain). Changes in the proportion of high-value cases after R-SCAN intervention were assessed for each cohort using generalized estimating equation logistic regression, and changes in the number of low-value cases were analyzed using Poisson regression.

RESULTS

Use of R-SCAN in the comprehensive cohort resulted in a greater proportion of high-value imaging cases (from 57% to 79%; odds ratio, 2.69; 95% confidence interval, 1.50-4.86; P = .001) and 345 fewer low-value cases after intervention (incidence rate ratio, 0.45; 95% confidence interval, 0.29-0.70; P < .001). Similar changes in proportion of high-value cases and number of low-value cases were found for the pulmonary embolism, adnexal cyst, and low back pain cohorts.

CONCLUSIONS

R-SCAN participation was associated with a reduced likelihood of inappropriate imaging and is thus a promising tool to enhance the quality of patient care and promote wise use of health care resources.

Higher Imaging Yield When Clinical Decision Support Is Used

OBJECTIVE

Increased utilization of CT pulmonary angiography (CTPA) for the evaluation of pulmonary embolism has been associated with decreasing diagnostic yields and rising concerns about the harms of unnecessary testing. The objective of this study was to determine whether clinical decision support (CDS) use would be associated with increased imaging yields after controlling for selection bias.

METHODS

We performed a retrospective cohort study in the emergency departments of two tertiary care hospitals of all CTPAs performed between August 2015 and September 2018. Providers ordering a CTPA are routed to an optional CDS tool, which allows them to use Wells' Criteria for pulmonary embolism. After propensity score matching, CTPA yield was calculated for the CDS-use and CDS-dismissal groups and stratified by provider type.

RESULTS

A total of 7,367 CTPAs were ordered during the study period. Of those, providers used the CDS tool in 2,568 (35%) cases and did not use the tool in 4,799 (65%) of cases. After propensity score matching, CTPA yield was 11.99% in the CDS-use group and 8.70% in the CDS-dismissal group (P < .001). Attending physicians, residents, and physician assistant CDS users demonstrated a 56.5% (P = .006), 38.7% (P = .01), and 16.7% (P = .03) increased yield compared with those who dismissed the tool, respectively.

DISCUSSION

Diagnostic yield was 38% higher for CTPAs when the provider used the CDS tool, after controlling for selection bias. Yields were higher for every provider type. Further research is needed to discover successful strategies to increase provider use of these important tools.

Assessment of the current D-dimer cutoff point in pulmonary embolism workup at a single institution: Retrospective study

Background:

The currently used D-dimer (DD) cutoff point is associated with a large number of negative CT-pulmonary angiographies (CTPA). We hypothesized presence of deficiency in the current cutoff and a need to look for a better DD threshold.

Materials and Methods:

We conducted a retrospective medical records analysis of all patients who had a CTPA as part of pulmonary embolism (PE) workup over a 1-year period. All emergency room (ER) patients who had DD assay checked prior to CTPA were included in the analysis. We assessed our institutional cutoff point and tried to test other presumptive DD thresholds retrospectively.

Results:

At our institution 1591 CTPA were performed in 2014, with 1220 scans (77%) performed in the ER. DD test was ordered prior to CTPA imaging in 238 ER patients (19.5%) as part of the PE workup. PE was diagnosed in 14 cases (6%). The sensitivity and specificity of the currently used DD cutoff (0.5 mcg/mL) were found to be 100% and 13%, respectively. Shifting the cutoff value from 0.5 to 0.85 mcg/mL would result in a significant increase in the specificity from 13% to 51% while maintaining the same sensitivity of 100%. This would make theoretically 84 CTPA scans, corresponding to 35% of CTPA imaging, unnecessary because DD would be considered negative based on this presumptive threshold.

Conclusions:

Our results suggest a significant deficiency in the institutional DD cutoff point with the need to find a better threshold through a large multicenter prospective trial to minimize unnecessary CTPA scans and to improve patient safety.

Clinical presentation and diagnostic work up of suspected pulmonary embolism in a district hospital emergency centre serving a high HIV/TB burden population

Introduction

The diagnosis of pulmonary embolism (PE) is challenging to make and is often missed in the emergency centre. The diagnostic work-up of PE has been improved by the use of clinical decision rules (CDRs) and CT pulmonary angiography (CTPA) in high-income countries. CDRs have not been validated in the South African environment where HIV and tuberculosis (TB) are highly prevalent. Both conditions are known to induce a hyper-coagulable state. The objective of this study was to describe the clinical presentation and diagnostic workup of suspected PE in our setting and to determine the prevalence of HIV and TB in our sample of patients with confirmed PE.

Methods

This study was a retrospective chart review of patients with suspected PE who had CTPAs performed between October 2013 and October 2015 at a district hospital in Cape Town, South Africa. Data were collected on demographics, presenting signs and symptoms, vitals, bedside investigations, HIV and TB status. A Revised Geneva score (RGS) was calculated retrospectively and compared to the CTPA result.

Results

The median age of patients with confirmed PE was 45 years and 68% were female. The CTPA yield for PE in our study population was 32%. The most common presenting complaint was dyspnoea (83%). Deep venous thrombosis (DVT) was present in 29%. No sign or symptom was observed to be markedly different in patients with confirmed PE vs no PE. Among patients with confirmed PE, 37% were HIV positive and 52% had current TB. RGS compared poorly with CTPA results.

Conclusions

PE remains a diagnostic challenge. In our study, the retrospectively calculated CDR was not predictive of PE in a population with a high prevalence of HIV and TB. Emergency physicians should be cautious when making a clinical probability assessment of PE in this setting. However, further studies are needed to develop a predictive CDR for the local environment.

Development and Performance of the Pulmonary Embolism Result Forecast Model (PERFORM) for Computed Tomography Clinical Decision Support

IMPORTANCE

Pulmonary embolism (PE) is a life-threatening clinical problem, and computed tomographic imaging is the standard for diagnosis. Clinical decision support rules based on PE risk-scoring models have been developed to compute pretest probability but are underused and tend to underperform in practice, leading to persistent overuse of CT imaging for PE.

OBJECTIVE

To develop a machine learning model to generate a patient-specific risk score for PE by analyzing longitudinal clinical data as clinical decision support for patients referred for CT imaging for PE.

DESIGN, SETTING, AND PARTICIPANTS

In this diagnostic study, the proposed workflow for the machine learning model, the Pulmonary Embolism Result Forecast Model (PERFORM), transforms raw electronic medical record (EMR) data into temporal feature vectors and develops a decision analytical model targeted toward adult patients referred for CT imaging for PE. The model was tested on holdout patient EMR data from 2 large, academic medical practices. A total of 3397 annotated CT imaging examinations for PE from 3214 unique patients seen at Stanford University hospitals and clinics were used for training and validation. The models were externally validated on 240 unique patients seen at Duke University Medical Center. The comparison with clinical scoring systems was done on randomly selected 100 outpatient samples from Stanford University hospitals and clinics and 101 outpatient samples from Duke University Medical Center.

MAIN OUTCOMES AND MEASURES

Prediction performance of diagnosing acute PE was evaluated using ElasticNet, artificial neural networks, and other machine learning approaches on holdout data sets from both institutions, and performance of models was measured by area under the receiver operating characteristic curve (AUROC).

RESULTS

Of the 3214 patients included in the study, 1704 (53.0%) were women from Stanford University hospitals and clinics; mean (SD) age was 60.53 (19.43) years. The 240 patients from Duke University Medical Center used for validation included 132 women (55.0%); mean (SD) age was 70.2 (14.2) years. In the samples for clinical scoring system comparisons, the 100 outpatients from Stanford University hospitals and clinics included 67 women (67.0%); mean (SD) age was 57.74 (19.87) years, and the 101 patients from Duke University Medical Center included 59 women (58.4%); mean (SD) age was 73.06 (15.3) years. The best-performing model achieved an AUROC performance of predicting a positive PE study of 0.90 (95% CI, 0.87-0.91) on intrainstitutional holdout data with an AUROC of 0.71 (95% CI, 0.69-0.72) on an external data set from Duke University Medical Center; superior AUROC performance and cross-institutional generalization of the model of 0.81 (95% CI, 0.77-0.87) and 0.81 (95% CI, 0.73-0.82), respectively, were noted on holdout outpatient populations from both intrainstitutional and extrainstitutional data.

CONCLUSIONS AND RELEVANCE

The machine learning model, PERFORM, may consider multitudes of applicable patient-specific risk factors and dependencies to arrive at a PE risk prediction that generalizes to new population distributions. This approach might be used as an automated clinical decision-support tool for patients referred for CT PE imaging to improve CT use.

Evaluation of Cancer Patients With Suspected Pulmonary Embolism: Performance of the American College of Physicians Guideline

BACKGROUND

Accurate risk stratification of pulmonary embolism (PE) can reduce unnecessary imaging. We investigated the extent to which the American College of Physicians (ACP) guideline for evaluation of patients with suspected PE could be applied to cancer patients in the emergency department of a comprehensive cancer center.

MATERIALS AND METHODS

Data from cancer patients who underwent CT pulmonary angiography (CTPA) between August 1, 2015, and October 31, 2015, were collected. We assessed each patient's diagnostic workup for its adherence to the ACP guideline in terms of clinical risk stratification and age-adjusted d-dimer level and the degree to which these factors were associated with PE.

RESULTS

Of the 380 patients identified, 213 (56%) underwent CTPA indicated per the ACP guideline, and 78 (21%) underwent CTPA not indicated per the guideline. Only one of the patients who underwent nonindicated CTPA had a PE. Fifty-seven patients underwent unnecessary d-dimer evaluation, and 71 patients with negative d-dimer test results underwent nonindicated CTPA. PEs were found in 6 of 108 (6%) low-risk patients, 22 of 219 (10%) intermediate-risk patients, and 13 of 53 (25%) high-risk patients. The ACP guideline had negative predictive value of 99% (95% confidence interval: 93%-100%) and sensitivity of 97% (95% confidence interval: 86%-100%) in predicting PE.

CONCLUSION

The ACP guideline has good sensitivity for detecting PE in cancer patients and thus can be applied in this population. Compliance with the ACP guideline when evaluating cancer patients with suspected PE could reduce the use of unnecessary imaging and laboratory studies.

Potential Effect of the Protecting Access to Medicare Act on Use of Advanced Diagnostic Imaging in the Emergency Department: An Analysis of the National Hospital Ambulatory Care Survey

Background Clinical decision support is increasingly used to enhance clinicians' exposure to established evidence and patient information during an episode of patient care. Pending legislation specifies clinical decision support before performing advanced imaging at emergency department (ED) visits. Purpose To estimate the volume of advanced imaging tests (CT and MRI) that would require use of clinical decision support to achieve Protecting Access to Medicare Act (PAMA) compliance in the ED. Materials and Methods A retrospective, cross-sectional analysis of ED visits was conducted by using data from the 2012-2015 National Hospital Ambulatory Care Survey. PAMA-related visits were identified by selecting the patient reasons for visit (RFVs) related to the eight clinical conditions. Results Among the adult ED visits, 26.7% (20 506 of 77 299, representing 113 000 000 visits across 4 years, or 28 000 000 visits annually) patients presented with a RFV consistent with a PAMA priority clinical area (PCA). Among visits in which a patient described an RFV code consistent with a PAMA PCA, up to 22.9% (4681 of 20 506; 95% confidence interval: 21.8%, 24.1%) patients underwent advanced imaging, translating to approximately 6 000 000 visits annually. Conclusion Protecting Access to Medicare Act legislation targets eight priority clinical areas, estimated to be prevalent among one in four adult emergency department visits. CT and/or MRI studies are performed during up to 23% of these visits. Depending on the particular clinical decision support systems selected within a health system, and how they are implemented, the potential volume of studies in which clinicians must interact with clinical decision support system may either exceed or fall short of these estimates. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Forman in this issue.

Automated Pulmonary Embolism Risk Classification and Guideline Adherence for Computed Tomography Pulmonary Angiography Ordering

BACKGROUND

The assessment of clinical guideline adherence for the evaluation of pulmonary embolism (PE) via computed tomography pulmonary angiography (CTPA) currently requires either labor-intensive, retrospective chart review or prospective collection of PE risk scores at the time of CTPA order. The recording of clinical data in a structured manner in the electronic health record (EHR) may make it possible to automate the calculation of a patient's PE risk classification and determine whether the CTPA order was guideline concordant.

OBJECTIVES

The objective of this study was to measure the performance of automated, structured data-only versions of the Wells and revised Geneva risk scores in emergency department (ED) encounters during which a CTPA was ordered. The hypothesis was that such an automated method would classify a patient's PE risk with high accuracy compared to manual chart review.

METHODS

We developed automated, structured data-only versions of the Wells and revised Geneva risk scores to classify 212 ED encounters during which a CTPA was performed as "PE likely" or "PE unlikely." We then combined these classifications with D-dimer ordering data to assess each encounter as guideline concordant or discordant. The accuracy of these automated classifications and assessments of guideline concordance were determined by comparing them to classifications and concordance based on the complete Wells and revised Geneva scores derived via abstractor manual chart review.

RESULTS

The automatically derived Wells and revised Geneva risk classifications were 91.5 and 92% accurate compared to the manually determined classifications, respectively. There was no statistically significant difference between guideline adherence calculated by the automated scores compared to manual chart review (Wells, 70.8% vs. 75%, p = 0.33; revised Geneva, 65.6% vs. 66%, p = 0.92).

CONCLUSION

The Wells and revised Geneva score risk classifications can be approximated with high accuracy using automated extraction of structured EHR data elements in patients who received a CTPA. Combining these automated scores with D-dimer ordering data allows for the automated assessment of clinical guideline adherence for CTPA ordering in the ED, without the burden of manual chart review.

The DAGMAR Score: D-dimer assay-guided moderation of adjusted risk. Improving specificity of the D-dimer for pulmonary embolism

We generated a novel scoring system to improve the test characteristics of D-dimer in patients with suspected PE (pulmonary emboli). Electronic Medical Record data were retrospectively reviewed on Emergency Department (ED) patients 18 years or older for whom a D-dimer and imaging were ordered between June 4, 2012 and March 30, 2016. Symptoms (dyspnea, unilateral leg swelling, hemoptysis), age, vital signs, medical history (cancer, recent surgery, medications, history of deep vein thrombosis or PE, COPD, smoking), laboratory values (quantitative D-dimer, platelets, and mean platelet volume (MPV)), and imaging results (CT, VQ) were collected. Points were designated to factors that were significant in two multiple regression analyses, for PE or positive D-dimer. Points predictive of PE were designated positive values and points predictive of positive D-dimer, irrespective of presence of PE, were designated negative values. The DAGMAR (D-dimer Assay-Guided Moderation of Adjusted Risk) score was developed using age and platelet adjustment and points for factors associated with PE and elevated D-dimer. Of 8486 visits reviewed, 3523 were unique visits with imaging, yielding 2253 (26.5%) positive D-dimers. 3501 CT scans and 156 VQ scans were completed, detecting 198 PE. In our cohort, a DAGMAR Score < 2 equated to overall PE risk < 1.2%. Specificity improved (38% to 59%) without compromising sensitivity (94% to 96%). Use of the DAGMAR Score would have reduced CT scans from 2253 to 1556 and lead to fewer false negative results. By considering factors that affect D-dimer and also PE, we improved specificity without compromising sensitivity.

Long-Term Experience With a Mandatory Clinical Decision Rule and Mandatory d-Dimer in the Evaluation of Suspected Pulmonary Embolism

PURPOSE

This study evaluated the long-term effectiveness of mandatory assignment of both a clinical decision rule (CDR) and highly sensitive d-dimer in the evaluation of patients with suspected pulmonary embolism (PE).

MATERIALS AND METHODS

Institutional guidelines with a CDR and highly sensitive d-dimer were embedded in an order entry menu with mandatory assignment of key components before ordering a CT pulmonary angiogram (CTPA). Data were retrospectively extracted from the electronic health record.

RESULTS

This was a retrospective review of 1,003 CTPA studies (905 patients, 845 male and 60 female patients, age 63.7 ± 13.5 years). CTPAs were positive for PE in 170 studies (17%), representing an average yield of 15% (year [average]; 2007 [15%], 2008 [18%], 2009 [15%], 2010 [15%], 2011 [17%], 2012 [15%], 2013 [23%]). The increased yield represented efforts of mandatory order entry assignments, educational sessions, and clinical champions. Different d-dimer thresholds with or without age adjustments in combination with the CDR identified about 10% of patients who may have been managed without CTPA.

CONCLUSION

Mandatory assignment of a CDR and highly sensitive d-dimer clinical decision pathway can be successfully incorporated into an order entry menu and produce a sustained increase in CTPA yield of patients with suspected PE.

ACR Appropriateness Criteria® Acute Chest Pain-Suspected Pulmonary Embolism

Pulmonary embolism (PE) remains a common and important clinical condition that cannot be accurately diagnosed on the basis of signs, symptoms, and history alone. The diagnosis of PE has been facilitated by technical advancements and multidetector CT pulmonary angiography, which is the major diagnostic modality currently used. Ventilation and perfusion scans remain largely accurate and useful in certain settings. Lower-extremity ultrasound can substitute by demonstrating deep vein thrombosis; however, if negative, further studies to exclude PE are indicated. In all cases, correlation with the clinical status, particularly with risk factors, improves not only the accuracy of diagnostic imaging but also overall utilization. Other diagnostic tests have limited roles. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Use of the d-dimer for Detecting Pulmonary Embolism in the Emergency Department

BACKGROUND

Assessment for pulmonary embolism (PE) in the emergency department (ED) remains complex, involving clinical decision tools, blood tests, and imaging.

OBJECTIVE

Our objective was to examine the test characteristics of the high-sensitivity d-dimer for the diagnosis of PE at our institution and evaluate use of the d-dimer and factors associated with a falsely elevated d-dimer.

METHODS

We retrospectively collected data on adult patients evaluated with a d-dimer and computed tomography (CT) pulmonary angiogram or ventilation perfusion scan at two EDs between June 4, 2012 and March 30, 2016. We collected symptoms (dyspnea, unilateral leg swelling, hemoptysis), vital signs, and medical and social history (cancer, recent surgery, medications, history of deep vein thrombosis or PE, chronic obstructive pulmonary disease, smoking). We calculated test characteristics, including sensitivity, specificity, and likelihood ratios for the assay using conventional threshold and with age adjustment, and performed a univariate analysis.

RESULTS

We found 3523 unique visits with d-dimer and imaging, detecting 198 PE. Imaging was pursued on 1270 patients with negative d-dimers, revealing 9 false negatives, and d-dimer was sent on 596 patients for whom negative Pulmonary Embolism Rule-Out Criteria (PERC) were documented with 2% subsequent radiographic detection of PE. The d-dimer showed a sensitivity of 95.7% (95% confidence interval [CI] 91-98%), specificity of 40.0% (95% CI 38-42%), negative likelihood ratio of 0.11 (95% CI 0.06-0.21), and positive likelihood ratio of 1.59 (95% CI 1.53-1.66) for the radiographic detection of PE. With age adjustment, 347 of the 2253 CT scans that were pursued in patients older than 50 years with an elevated d-dimer could have been avoided without missing any additional PE. Many risk factors, such as age, history of PE, recent surgery, shortness of breath, tachycardia and hypoxia, elevated the d-dimer, regardless of the presence of PE.

CONCLUSIONS

Many patients with negative d-dimer and PERC still received imaging. Our data support the use of age adjustment, and perhaps adjustment for other factors seen in patients evaluated for PE.

Computed tomography pulmonary angiography is overused to diagnose pulmonary embolism in the emergency department of academic community hospital

Background: Pulmonary embolism (PE) is a common disease in the USA responsible for up to 10% of hospital mortality. Modified wells score (MWS) and D-dimer assay are used to categorize patients into high or low probability of PE. Patient with high probability need Computed tomography pulmonary angiography (CTPA), while patients with low probability and low D-dimer can safely forgo the CTPA. Objectives: The aim of this study was to investigate the rate of inappropriate CTPA use in the emergency department of a community teaching hospital. Methods: A retrospective chart review of adult patients who underwent CTPA for suspected PE in the emergency department for 2015 was done. CTPA use was considered inappropriate if MWS was less than or equal to 4 and D-dimer was either not ordered or its value was less than 500 μg/L. Bivariate analysis with Fisher’s exact tests and Student’s t-tests as well as multivariate logistic regression analysis were done to examine relationship between study explanatory variables and study outcome.

Results: 295 patients were included in the study. The mean age was 51.2(±14.5) years, 68.8% were females. The prevalence of PE was 5.4% and 41% of the CTPAs -were inappropriately ordered. Males were twice (OR 2.1; 95% CI 1.2, 3.6) as likely as females to have an inappropriately ordered CTPA after controlling for a high MWS, age, and tobacco history.

Conclusion: CTPA is overused to diagnose PE in the emergency department. Quality improvement projects are needed to encourage physicians to adhere to the current guidelines.

Implications of language barrier on the diagnostic yield of computed tomography in pulmonary embolism

OBJECTIVES

To determine if a physician-patient language barrier impacts the diagnostic accuracy of pulmonary embolism (PE) evaluation.

METHODS

A retrospective chart review, conducted between June 2015 and December 2016, of a consecutive sample of diagnostic computed tomography pulmonary angiogram (CTPA) studies performed on adult patients. Positive and negative CTPA scans were further categorized by patient language and the positive diagnostic yield was determined for each language group. A post collection sub-analysis was performed to determine the yield when interpreter services were identified as necessary.

RESULTS

The yield for English speaking patients was 10.24% (92/898, 95% CI 8.39% to 12.36%), similar to the yield in Spanish speaking patients of 9.40% (25/266, 95% CI 6.31% to 13.37%, P=0.69). This contrasted with the yield in patients who identified as bilingual, which was significantly lower at 1.41% (1/71, 95% CI 0.07% to 6.75%) compared to both English-(P<0.02) and Spanish-only speakers (P<0.03). The yield for non-English speaking patients who requested an interpreter was 7.37% (14/190, 95% CI 4.26% to 11.77%) versus 3.23% (2/62, 95% CI 0.54% to 10.25%, P=0.25) in those who did not.

CONCLUSIONS

The diagnostic yield in English- and Spanish-only speaking patients was similar, however, the yield in those that self-identified as bilingual was significantly lower. In patient groups in which a language barrier existed and an interpreter was not utilized, there was a trend toward a lower diagnostic yield. This suggests an increased propensity to order diagnostic imaging when potential communication barriers exist.

Addressing overuse in emergency medicine: evidence of a role for greater patient engagement

Overuse of health care refers to tests, treatments, and even health care settings when used in circumstances where they are unlikely to help. Overuse is not only wasteful, it threatens patient safety by exposing patients to a greater chance of harm than benefit. It is a widespread problem and has proved resistant to change. Overuse of diagnostic testing is a particular problem in emergency medicine. Emergency physicians cite fear of missing a diagnosis, fear of law suits, and perceived patient expectations as key contributors. However, physicians' assumptions about what patients expect are often wrong, and overlook two of patients' most consistently voiced priorities: communication and empathy. Evidence indicates that patients who are more fully informed and engaged in their care often opt for less aggressive approaches. Shared decision making refers to (1) providing balanced information so that patients understand their options and the trade-offs involved, (2) encouraging them to voice their preferences and values, and (3) engaging them-to the extent appropriate or desired-in decision making. By adopting this approach to discretionary decision making, physicians are better positioned to address patients' concerns without the use of tests and treatments patients neither need nor value.

Qualitative Study to Understand Ordering of CT Angiography to Diagnose Pulmonary Embolism in the Emergency Room Setting

PURPOSE

To better understand the decision making behind the ordering of CT pulmonary angiography (CTPA) for the diagnosis of pulmonary embolism (PE) in the emergency department.

METHODS

We conducted semistructured interviews with our institution's emergency medicine (EM) providers and radiologists who read CTPAs performed in the emergency department. We employed the Theoretical Domains Framework-a formal, structured approach used to better understand the motivations and beliefs of physicians surrounding a complex medical decision making-to categorize the themes that arose from our interviews.

RESULTS

EM providers were identified as the main drivers of CTPA ordering. Both EM and radiologist groups perceived the radiologist's role as more limited. Experience- and gestalt-based heuristics were the most important factors driving this decision and more important, in many cases, than established algorithms for CTPA ordering. There were contrasting views on the value of d-dimer in the suspected PE workup, with EM providers finding this test less useful than radiologists. EM provider and radiologist suggestions for improving the appropriateness of CTPA ordering consisted of making this process more arduous and incorporating d-dimer tests and prediction rules into a decision support tool.

CONCLUSION

EM providers were the main drivers of CTPA ordering, and there was a marginalized role for the radiologist. Experience- and gestalt-based heuristics were the main influencers of CTPA ordering. Our findings suggest that a more nuanced intervention than simply including a d-dimer and a prediction score in each preimaging workup may be necessary to curb overordering of CTPA in patients suspected of PE.

D-Dimer Use and Pulmonary Embolism Diagnosis in Emergency Units: Why Is There Such a Difference in Pulmonary Embolism Prevalence between the United States of America and Countries Outside USA?

OBJECTIVE

Although diagnostic guidelines are similar, there is a huge difference in pulmonary embolism (PE) prevalence between the United States of America (US) and countries outside the USA (OUS) in the emergency care setting. In this study, we prospectively analyze patients' characteristics and differences in clinical care that may influence PE prevalence in different countries.

METHODS

An international multicenter prospective diagnostic study was conducted in a standard-of-care setting. Consecutive outpatients presenting to the emergency unit and suspected for PE were managed using the Wells score, STA-Liatest® D-Dimers and imaging.

RESULTS

The prevalence of PE in the study was 7.9% in low and moderate risk patients. Among the 1060 patients with low or moderate pre-test probability (PTP), PE prevalence was four times higher in OUS (10.7%) than in the US (2.5%) (P < 0.0001). The mean number of imaging procedures performed for one new PE diagnosis was 3.3 in OUS vs 17 in the US (P < 0.001). Stopping investigation in the case of negative D-dimers (DD combined) with low/moderate PTP was more frequent in OUS (92.7%) than in the US (75.7%) (P < 0.01). Moreover, the use of imaging was much higher in the US (44.4% vs 19.2% in OUS) in the case of moderate PTP combined with negative DD.

CONCLUSION

Differences between US and OUS PE prevalence in emergency setting might be explained by differences in patients' characteristics and mostly in care patterns. US physicians performed computed tomographic pulmonary angiography more often than in Europe in cases of low/moderate PTP combined with negative DD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01221805.

The Determinants of Productivity in Medical Testing: Intensity and Allocation of Care

A large body of research has investigated whether physicians overuse care. There is less evidence on whether, for a fixed level of spending, doctors allocate resources to patients with the highest expected returns. We assess both sources of inefficiency exploiting variation in rates of negative imaging tests for pulmonary embolism. We document enormous across-doctor heterogeneity in testing conditional on patient population, which explains the negative relationship between physicians' testing rates and test yields. Furthermore, doctors do not target testing to the highest risk patients, reducing test yields by one third. Our calibration suggests misallocation is more costly than overuse.

Yield of CT Pulmonary Angiography in the Emergency Department When Providers Override Evidence-based Clinical Decision Support

Purpose To determine the frequency of, and yield after, provider overrides of evidence-based clinical decision support (CDS) for ordering computed tomographic (CT) pulmonary angiography in the emergency department (ED). Materials and Methods This HIPAA-compliant, institutional review board-approved study was performed at a tertiary care, academic medical center ED with approximately 60 000 annual visits and included all patients who were suspected of having pulmonary embolism (PE) and who underwent CT pulmonary angiography between January 1, 2011, and August 31, 2013. The requirement to obtain informed consent was waived. Each CT order for pulmonary angiography was exposed to CDS on the basis of the Wells criteria. For patients with a Wells score of 4 or less, CDS alerts suggested d-dimer testing because acute PE is highly unlikely in these patients if d-dimer levels are normal. The yield of CT pulmonary angiography (number of positive PE diagnoses/total number of CT pulmonary angiographic examinations) was compared in patients in whom providers overrode CDS alerts (by performing CT pulmonary angiography in patients with a Wells score ≤4 and a normal d-dimer level or no d-dimer testing) (override group) and those in whom providers followed Wells criteria (CT pulmonary angiography only in patients with Wells score >4 or ≤4 with elevated d-dimer level) (adherent group). A validated natural language processing tool identified positive PE diagnoses, with subsegmental and/or indeterminate diagnoses removed by means of chart review. Statistical analysis was performed with the χ² test, the Student t test, and logistic regression. Results Among 2993 CT pulmonary angiography studies in 2655 patients, 563 examinations had a Wells score of 4 or less but did not undergo d-dimer testing and 26 had a Wells score of 4 or less and had normal d-dimer levels. The yield of CT pulmonary angiography was 4.2% in the override group (25 of 589 studies, none with a normal d-dimer level) and 11.2% in the adherent group (270 of 2404 studies) (P < .001). After adjustment for the risk factor differences between the two groups, the odds of an acute PE finding were 51.3% lower when providers overrode alerts than when they followed CDS guidelines. Comparison of the two groups including only patients unlikely to have PE led to similar results. Conclusion The odds of an acute PE finding in the ED when providers adhered to evidence presented in CDS were nearly double those seen when providers overrode CDS alerts. Most overrides were due to the lack of d-dimer testing in patients unlikely to have PE. ^© RSNA, 2016.

Yield of computed tomography pulmonary angiogram in the emergency department in cancer patients suspected to have pulmonary embolism

OBJECTIVE/BACKGROUND

The use of computed tomography pulmonary angiography (CTPA) in the emergency department (ED) for patients suspected to have pulmonary embolism (PE) has been steadily rising in the last 2decades. However, there are limited studies that specifically address the use of CTPA in the ED for cancer patients suspected to have PE. The objective of this study is to assess the rate of positive PE by CTPA in the ED in cancer patients and the variables that are associated with positive results.

METHODS

A retrospective review of electronic medical records for 208 consecutive patients with cancer who presented to the ED and received a CTPA for suspected PE over a 12-month period. The review included demographics, type and status of cancer, presenting symptoms, CTPA results, calculation of Wells Score, management based on CT findings, and outcome of patients.

RESULTS

Among the 208 patients who met the inclusion criteria during our study period (mean age 57±13.37years, 73% women, 59% African American, and 32% Caucasians), 5.7% were diagnosed with PE. One hundred and eighty-two (83.7%) had a Wells Score ⩽4, of which 2.2% were found to have to have PE, 22 (16.3%) patients had a Wells Score >4, of which 36.4% were found to have PE (p<.0001). Sensitivity and specificity of Wells >4 was 66.7% and 92.9%, respectively, with an odds ratio of 27 (95% CI 6.6-113.6). Receiver operator characteristics area under the curve for Wells Score was 0.868. Age, race, sex, malignancy type, stage, status, clinical presentation, D-dimer, and a previous history of venous thromboembolism were not found to have statistically significant predictive values.

CONCLUSION

The yield of CTPA to rule out PE in patients with cancer presenting in the ED is low. Following a validated decision-making protocol such as Wells Criteria may significantly decrease the number of CTPA used in the ED.

CT Pulmonary Angiography: Using Decision Rules in the Emergency Department

PURPOSE

The aim of this study was to assess the appropriateness of utilization and diagnostic yields of CT pulmonary angiography (CTPA), comparing two commonly applied decision rules, the pulmonary embolism (PE) rule-out criteria (PERC) and the modified Wells criteria (mWells), in the emergency department (ED) setting.

METHODS

Institutional review board approval was obtained for this HIPAA-compliant, prospective-cohort, academic single-center study. Six hundred two consecutive adult ED patients undergoing CTPA for suspected PE formed the study population. The outcome was positive or negative for PE by CTPA and at 6-month follow-up. PERC and mWells scores were calculated. A positive PERC score was defined as meeting one or more criteria and a positive mWells score as >4. The percentage of CT pulmonary angiographic examinations that could have been avoided and the diagnostic yield of CTPA using PERC, mWells, and PERC applied to a negative mWells score were calculated.

RESULTS

The diagnostic yield of CTPA was 10% (61 of 602). By applying PERC, mWells, and PERC to negative mWells score, 17.6% (106 of 602), 45% (273 of 602), and 17.1% (103 of 602) of CT pulmonary angiographic examinations, respectively, could have been avoided. The diagnostic yield in PERC-positive patients was higher than in mWells-positive patients (10% [59 of 602] vs 8% [49 of 602], P < .0001). Among PERC-negative and mWells-negative patients, the diagnostic yields for PE were 1.9% (2 of 106) and 4% (12 of 273), respectively (P = .004). The diagnostic yield of a negative PERC score applied to a negative mWells score was 1.9% (2 of 103).

CONCLUSIONS

The use of PERC in the ED has the potential to significantly reduce the utilization of CTPA and misses fewer cases of PE compared with mWells, and it is therefore a more efficient decision tool.

Emergency Department Diagnostic Imaging: The Journey to Quality

Priorities in health care delivery are shifting, with a greater focus on enhancing value, incentivizing quality, and advancing population health. While measurement of quality in emergency department (ED) care is still in its infancy, performance measures are increasingly being linked to reimbursement to encourage the delivery of high-value care. With such changes, there will be growing oversight of diagnostic imaging in all clinical settings, including the ED. Here, the authors examine the current state of quality measurement as it pertains to ED imaging. The authors review relevant policies and discuss both the associated challenges and the facilitators of using quality measures to help optimize ED imaging. Understanding such factors will help ensure the delivery of diagnostic imaging that is appropriate, high-quality, and patient-centered.

Evaluation of Patients With Suspected Acute Pulmonary Embolism: Best Practice Advice From the Clinical Guidelines Committee of the American College of Physicians

DESCRIPTION

Pulmonary embolism (PE) can be a severe disease and is difficult to diagnose, given its nonspecific signs and symptoms. Because of this, testing patients with suspected acute PE has increased dramatically. However, the overuse of some tests, particularly computed tomography (CT) and plasma d-dimer measurement, may not improve care while potentially leading to patient harm and unnecessary expense.

METHODS

The literature search encompassed studies indexed by MEDLINE (1966-2014; English-language only) and included all clinical trials and meta-analyses on diagnostic strategies, decision rules, laboratory tests, and imaging studies for the diagnosis of PE. This document is not based on a formal systematic review, but instead seeks to provide practical advice based on the best available evidence and recent guidelines. The target audience for this paper is all clinicians; the target patient population is all adults, both inpatient and outpatient, suspected of having acute PE.

BEST PRACTICE ADVICE 1

Clinicians should use validated clinical prediction rules to estimate pretest probability in patients in whom acute PE is being considered.

BEST PRACTICE ADVICE 2

Clinicians should not obtain d-dimer measurements or imaging studies in patients with a low pretest probability of PE and who meet all Pulmonary Embolism Rule-Out Criteria.

BEST PRACTICE ADVICE 3

Clinicians should obtain a high-sensitivity d-dimer measurement as the initial diagnostic test in patients who have an intermediate pretest probability of PE or in patients with low pretest probability of PE who do not meet all Pulmonary Embolism Rule-Out Criteria. Clinicians should not use imaging studies as the initial test in patients who have a low or intermediate pretest probability of PE.

BEST PRACTICE ADVICE 4

Clinicians should use age-adjusted d-dimer thresholds (age × 10 ng/mL rather than a generic 500 ng/mL) in patients older than 50 years to determine whether imaging is warranted.

BEST PRACTICE ADVICE 5

Clinicians should not obtain any imaging studies in patients with a d-dimer level below the age-adjusted cutoff.

BEST PRACTICE ADVICE 6

Clinicians should obtain imaging with CT pulmonary angiography (CTPA) in patients with high pretest probability of PE. Clinicians should reserve ventilation-perfusion scans for patients who have a contraindication to CTPA or if CTPA is not available. Clinicians should not obtain a d-dimer measurement in patients with a high pretest probability of PE.

Pulmonary embolism response teams

OPINION STATEMENT

Pulmonary embolism (PE) is a complex and multidimensional pathophysiology, the diagnosis and management of which spans multiple disciplines. The high morbidity and associated mortality of "massive" and "submassive" acute PE may require prompt, definitive management; however, current consensus guidelines in this domain are not supported by high-level evidence. Randomized clinical trials comparing available pharmacologic and invasive treatment modalities-including anticoagulation, thrombolysis, and embolectomy-have not been conducted and continue to be challenging to conceptualize, design, and execute. Consequently, time-sensitive therapeutic determinations are largely not standardized, and rendered on a case-by-case basis in part depending on institutional practices and expertises. Chronic sequelae of PE, such as chronic thromboembolic pulmonary hypertension and right heart failure, are increasingly identified as conditions necessitating longitudinal specialty care. These and other challenges have created a niche for a multidisciplinary team which can respond rapidly to unstable patient scenarios, appropriately deploy resources, and offer highly specialized acute and chronic management of PE. The Massachusetts General Hospital Pulmonary Embolism Response Team (PERT), modeled after existing rapid response and collaborative care teams, is a novel approach that combines this clinical service with the development of an educational and research framework to advance the care of patients with PE.

Age and sex-dependent trends in pulmonary embolism testing and derivation of a clinical decision rule for young patients

IMPORTANCE

Despite low prevalence of pulmonary embolism (PE) in young adults, they are frequently imaged for PE, which involves radiation exposure and substantial financial cost.

OBJECTIVE

Determine the use and positive proportions for PE imaging by age, differences in clinical presentation of PE by age and the projected impact of an age-targeted decision rule.

DESIGN

Analysis of two national population-based datasets: the 2009 Nationwide Emergency Department Sample, a 20% sample of US emergency departments (EDs) and the 2003-2006 Pulmonary Embolism Rule-out Criteria (PERC) dataset, a multisite cohort of ED patients with suspected PE from 12 US EDs.

RESULTS

Prevalence of PE was 10 times lower in young patients (18-35 years) than in older patients (>65 years) (0.06% vs 0.60%, p<0.001), but young patients were imaged for PE almost as frequently as older patients (2.3% vs 3.2%). This resulted in a lower proportion of positive examinations in young adults than older adults (2.3% vs 17.4%, p<0.001 in women; 4.0% vs 21.4%, p<0.001 in men). Clinical predictors of PE varied by age. Tachycardia was a significant predictor of PE in older patients (OR: 1.2-1.9, p<0.001), but not young patients. Fever was a significant predictor only in young patients (OR: 1.4-7.2, p<0.01). A modification of the previously described PERC rule to include age-specific risk factors could reduce PE imaging by 51% in young patients, with a missed PE rate of 0.6% in those excluded from imaging.

CONCLUSIONS AND RELEVANCE

Young patients are frequently imaged for PE and have lower positive imaging rates than older patients. After further validation, application of our proposed rule for excluding young patients from PE imaging could reduce imaging, increase the positive rate of imaging and result in a low rate of missed PE among those excluded from imaging.

Effect of Evidence-based Clinical Decision Support on the Use and Yield of CT Pulmonary Angiographic Imaging in Hospitalized Patients

PURPOSE

To determine the effect of clinical decision support (CDS) on the use and yield of inpatient computed tomographic (CT) pulmonary angiography for acute pulmonary embolism (PE).

MATERIALS AND METHODS

This HIPAA-compliant, institutional review board-approved study with waiver of informed consent included all adults admitted to a 793-bed teaching hospital from April 1, 2007, to June 30, 2012. The CDS intervention, implemented after a baseline observation period, informed providers who placed an order for CT pulmonary angiographic imaging about the pretest probability of the study based on a validated decision rule. Use of CT pulmonary angiographic and admission data from administrative databases was obtained for this study. By using a validated natural language processing algorithm on radiology reports, each CT pulmonary angiographic examination was classified as positive or negative for acute PE. Primary outcome measure was monthly use of CT pulmonary angiography per 1000 admissions. Secondary outcome was CT pulmonary angiography yield (percentage of CT pulmonary angiographic examinations that were positive for acute PE). Linear trend analysis was used to assess for effect and trend differences in use and yield of CT pulmonary angiographic imaging before and after CDS.

RESULTS

In 272 374 admissions over the study period, 5287 patients underwent 5892 CT pulmonary angiographic examinations. A 12.3% decrease in monthly use of CT pulmonary angiography (26.0 to 22.8 CT pulmonary angiographic examinations per 1000 admissions before and after CDS, respectively; P = .008) observed 1 month after CDS implementation was sustained over the ensuing 32-month period. There was a nonsignificant 16.3% increase in monthly yield of CT pulmonary angiography or percentage of CT pulmonary angiographic examinations positive for acute PE after CDS (P = .65).

CONCLUSION

Implementation of evidence-based CDS for inpatients was associated with a 12.3% immediate and sustained decrease in use of CT pulmonary angiographic examinations in the evaluation of inpatients for acute PE. for this article.