Pulmonary embolism rule-out criteria (PERC) in pulmonary embolism—revisited: A systematic review and meta-analysis

Pulmonary Embolism Rule-out Criteria: Diagnostic Accuracy and Impact of COVID-19

BACKGROUND

The Pulmonary Embolism Rule-Out Criteria (PERC), developed to minimize unnecessary testing in low-risk pulmonary embolism (PE) cases, lacks clear validation in the context of COVID-19.

OBJECTIVES

To assess the validity of the PERC in emergency department patients having undergone computed tomography pulmonary angiography (CTPA) during the COVID-19 pandemic.

METHODS

We conducted a retrospective analysis of emergency department patients who underwent CTPA for suspected PE. COVID-19 status was based on the results of a reverse transcription-polymerase chain reaction (RT-PCR) test performed in the emergency department, or within 30 days prior to visiting the emergency department. We collected data on demographics, symptoms, d-dimer levels, and medical history relevant to thrombosis and conducted the PERC test using the criteria including age, oxygen saturation, heart rate, and the absence of hemoptysis or recent trauma. We categorized outcomes based on the concordance between the PERC results and CTPA findings, with specific definitions for true positive and negative, as well as false positive and negative results. We also evaluated the impact of COVID-19 status on the diagnostic performance of the PERC by analyzing the prevalence of PE in patients testing positive and negative for COVID-19.

RESULTS

Among the 2.430 participants, 45.1% tested negative for COVID-19, 43.4% tested positive, and 11.5% were untested. The PERC identified 91.2% of the cases as positive, 6.9% of which were confirmed to have PE. Overall, 84.9% of cases (n = 2.062) showed a discordant result between the PERC and CTPA findings. The lack of significant correspondence between the PERC positivity and actual PE presence (p = 0.001; p < 0.01) indicated low diagnostic concordance. In patients with a positive COVID-19 test result, the PERC demonstrated a sensitivity of 95.3% (95% CI: 86.91-99.02), a specificity of 9.1% (95% CI: 7.46-11.15), a positive predictive value of 6.3% (95% CI: 6.01-6.70), a negative predictive value of 96.8% (95% CI: 90.81-98.94), and an accuracy of 14.4% (95% CI: 12.34-16.67). In patients who tested negative for COVID-19, the sensitivity was 95.4% (95% CI: 88.64-98.73), the specificity was 7.8% (95% CI: 6.25-9.66), the positive predictive value was 8.1% (95% CI: 7.83-8.57), the negative predictive value was 95.1% (95% CI: 88.11-98.14), and the accuracy was 14.7% (95% CI: 12.73-17.02).

CONCLUSION

The study demonstrates that the sensitivity and negative predictive value of the PERC are comparable in COVID-19 positive and negative patients. Furthermore, the incidence of PE among patients presenting to the emergency department did not significantly differ based on COVID-19 status. While this study highlights the relevance of the PERC in clinical decision-making, caution is advised as the PERC may not always provide reliable results when used as the sole diagnostic test.

Clinical Presentation and Risk Stratification of Pulmonary Embolism

Pulmonary embolism (PE) presents with a spectrum of symptoms, ranging from asymptomatic cases to life-threatening events. Common symptoms include sudden dyspnea, chest pain, limb swelling, syncope, and hemoptysis. Clinical presentation varies based on thrombus burden, demographics, and time to presentation. Diagnostic evaluation involves assessing symptoms, physical examination findings, and utilizing laboratory tests, including D-dimer. Risk stratification using tools like Wells score, Pulmonary Embolism Severity Index, and Hestia criteria aids in determining the severity of PE. PE is categorized based on hemodynamic status, temporal patterns, and anatomic locations of emboli to guide in making treatment decisions. Risk stratification plays a crucial role in directing management strategies, with elderly and comorbid individuals at higher risk. Early identification and appropriate risk stratification are essential for effective management of PE. As we delve into this review article, we aim to enhance the knowledge base surrounding PE, contributing to improved patient outcomes through informed decision-making in clinical practice.

Safety of the pulmonary embolism rule-out criteria rule: Findings from the Registro Informatizado de la Enfermedad TromboEmbolica venosa (RIETE) registry

BACKGROUND

The diagnostic strategy for pulmonary embolism (PE) includes a D-dimer test when PE probability is low or intermediate, but false-positive D-dimer results are frequent and can result in an unnecessary computed tomography pulmonary angiogram. The PE rule-out criteria (PERC) rule excludes PE without D-dimer testing when pretest probability is <15%. The aim of this study was to assess the safety of the PERC rule strategy in patients included in the Registro Informatizado de la Enfermedad TromboEmbolica venosa (RIETE) registry.

METHODS

This retrospective cohort study used data from the RIETE registry, an ongoing, international prospective registry of patients with objectively confirmed venous thromboembolism. The primary outcome was the failure rate of the PERC strategy, represented by the proportion of PERC-negative (PERC-N) patients with a PE included in the registry. Secondary outcomes were a comparison of the clinical characteristics, treatment strategy, and outcome of PERC-N versus PERC-positive (PERC-P) patients at 3 months.

RESULTS

From 2001 to 2021, a total of 49,793 patients with acute PE were enrolled in the RIETE registry. We included 48,903 in the final analysis after exclusion of 890 patients with an undetermined PERC status. Only 346 patients were PERC-N with a failure rate of 0.7% (95% confidence interval 0.6%-0.8%). PERC-N patients presented more frequently with chest pain but less often with dyspnea, syncope, or hypotension. They also had subsegmental or segmental PE more frequently, were more often treated with direct oral anticoagulants, and received mechanical or pharmacological thrombolysis less often. In addition, PERC-N patients had a lower incidence of recurrent deep vein thrombosis, major bleeding, and death attributed to PE during the 3-month follow-up.

CONCLUSIONS

A low failure rate of the PERC rule was observed in the RIETE registry, thus supporting its use to safely identify patients with an unlikely probability of PE.

Clinical predictors of pulmonary embolism for inpatients: are computed tomography pulmonary angiograms being requested appropriately?

BACKGROUND

The heterogeneity of inpatient pulmonary embolism (PE) presentations may lead to computed tomography pulmonary angiograms (CTPA) being over-requested. Current clinical predictors for PE, including Wells criteria and Pulmonary Embolism Rule-out Criteria (PERC), have predominantly focussed on outpatient and emergency department populations.

AIM

To determine the clinical indicators for ordering inpatient CTPA and the predictors of positive scans for PE.

METHODS

Consecutive inpatient CTPA (performed >24 h after admission) from January 2017 to December 2017 were retrospectively reviewed. Variables including baseline characteristics, vital signs and risk factors for PE were extracted.

RESULTS

A total of 312 CTPA was reviewed (average patient age 67 years; 46% male) and 36 CTPA were positive for PE (11.5%). The average time to inpatient CTPA request was 7 days. Clinical indicators associated with positive scans were hypoxia (odds ratio (OR) 2.4; 95% confidence interval (CI) 1.1-5.6), tachypnoea (OR 2.5; 95% CI 1.2-6.0), recent surgery or immobilisation (OR 2.7; 95% CI 1.2-6.4), S1Q3T3 pattern on electrocardiogram (ECG; OR 7.2; 95% CI 1.4-35.7) and right bundle branch block pattern on ECG (OR 4.7; 95% CI 1.6-13.1). Hypotension, fever and malignancy were not significant. Both PERC and Wells criteria had poor positive predictive value (12% and 27% respectively), but the negative predictive value for PERC and Wells was 100% and 95.8% respectively.

CONCLUSION

Inpatient CTPA appear to be over-requested and can potentially be rationalised based on a combination of clinical predictors and Wells criteria and/or PERC rule. Further prospective studies are needed to develop accurate clinical decision tools targeted towards inpatients.

How to Combat Over-Testing for Patients Suspected of Pulmonary Embolism: A Narrative Review

The diagnosis of PE remains difficult in 2023 because the signs and symptoms are not sensible nor specific. The consequences of potential diagnostic errors can be dramatic, whether by default or by excess. Furthermore, the achievement of a simple diagnostic strategy, based on clinical probability assessment, D-dimer measurement and computed tomography pulmonary angiography (CTPA) leads to a new challenge for PE diagnosis: over-testing. Indeed, since the 2000s, the wide availability of CTPA resulted in a major increase in investigations with a mod I confirm erate increase in PE diagnosis, without any notable improvement in patient outcomes. Quite the contrary, the complications of anticoagulation for PE increased significantly, and the long-term consequences of imaging diagnostic radiation is an important concern, especially the risk of breast cancer for young women. As a result, several strategies have been proposed to fight over-testing. They are mostly based on defining a subgroup of patients for whom no specific exam should be required to rule-out PE and adjusting the D-dimer cutoff to allow the exclusion of PE without performing CTPA. This narrative review presents the advantages and limitations of these different strategies as well as the perspective in PE diagnosis.

Characteristics associated with diagnostic yield of imaging for deep venous thrombosis and pulmonary embolism in the emergency department, hospital, and office settings: An Optum Clinformatics claims database study (2015-2019)

BACKGROUND

Different patient characteristics influence the decision to order diagnostic imaging for deep venous thrombosis (DVT) and pulmonary embolism (PE) in different settings (emergency department (ED), hospital, and office). Diagnostic yield is defined as the proportion of tests that report positive results. We hypothesize different patient characteristics are associated with higher or lower diagnostic yield of imaging for DVT and PE in different settings.

METHODS

We used Optum Clinformatics™ national claims database (2015-2019) to assess the diagnostic yield of imaging for DVT and PE in three settings: (a) ED discharge, (b) Hospitalized, and (c) Office. We studied the patient characteristics associated with diagnostic yield using logistic regression.

RESULTS

Diagnostic imaging for DVT and PE was performed in 1,502,417 and 710,263 visits, respectively. Diagnostic yield for DVT and PE was 9.8 ± 0.1 % and 12.7 ± 0.1 %, respectively in the overall cohort. In the ED discharge, hospitalized, and office settings, diagnostic yield for DVT was 10.4 ± 0.1 %, 16.9 ± 0.1 %, and 6.5 ± 0.1 %, respectively, and that for PE 6.4 ± 0.1 %, 18.7 ± 0.1 %, and 8.8 ± 0.2 %, respectively. Of the patients who underwent imaging for DVT, higher diagnostic yield was more likely with thrombophilia, central venous access, and cancer. Of the patients who underwent imaging for PE, higher diagnostic yield was most likely with thrombophilia, respiratory failure, and heart failure or acute myocardial infarction.

CONCLUSIONS

In each setting, different patient characteristics influence the diagnostic yield of imaging for DVT and PE and can inform clinical practice. Judicious use of imaging for DVT and PE could reduce costs and avoid exposure to radiation and contrast.

Epidemiology and clinical characteristics of posttraumatic hospitalized patients with symptoms related to venous thromboembolism: a single-center retrospective study

Purpose

The aim of this study was to investigate the epidemiology of trauma inpatients with venous thromboembolism (VTE) symptoms diagnosed using computed tomographic angiography (CTA) in Korea.

Methods

In total, 7,634 patients admitted to the emergency department of Gachon University Gil Medical Center, a tertiary hospital, and hospitalized between July 1, 2018 and December 31, 2020 were registered for this study. Of these patients, 278 patients who underwent CTA were enrolled in our study.

Results

VTE was found in 120 of the 7,634 patients (1.57%), and the positive diagnosis rate of the 278 patients who underwent CTA was 43.2% (120 of 278). The incidence of VTE was statistically significantly higher among those with severe head and neck injuries (Abbreviated Injury Scale, 3-5) than among those with nonsevere head and neck injuries (Abbreviated Injury Scale, 0-2; P=0.038). In a subgroup analysis, the severe and nonsevere head and neck injury groups showed statistically significant differences in known independent risk factors for VTE. In logistic regression analysis, the adjusted odds ratio of severe head and neck injury (Abbreviated Injury Scale, 3-5) for VTE was 1.891 (95% confidence interval, 1.043-3.430).

Conclusions

Trauma patients with severe head and neck injuries are more susceptible to VTE than those with nonsevere head and neck injuries. Thus, physicians must consider CTA as a priority for the diagnosis of VTE in trauma patients with severe head and neck injuries who show VTE-associated symptoms.

Performance of 2 Single-Item Screening Questions to Identify Future Homelessness Among Emergency Department Patients

IMPORTANCE

Despite increasing interest in assessing patient social needs in health care settings, there has been little research examining the performance of housing-related screening questions.

OBJECTIVE

To examine the performance of 2 single-item screening questions assessing emergency department (ED) patients' self-perceived risk of future homelessness.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study was conducted among a randomly selected sample of adult ED patients from 2016 to 2017 in a public hospital ED in New York City. Data were analyzed from September 2019 through October 2021.

EXPOSURES

Responses on patient surveys conducted at the baseline ED visit for 2 single-item screening questions on self-perceived risk for future housing instability and homelessness were collected. One question asked patients if they were worried about having stable housing in the next 2 months, and the other question asked them to rate the likelihood that they would enter a homeless shelter in the next 6 months.

OUTCOMES

Homeless shelter entry 2, 6, and 12 months after an ED visit, assessed using shelter administrative data in the study city, which was linked with participant baseline survey responses.

RESULTS

There were 1919 study participants (976 [51.0%] men and 931 [48.6%] women among 1915 individuals with gender data; 700 individuals aged 31-50 years [36.5%] among 1918 individuals with age data; 1126 Hispanic or Latinx individuals [59.0%], 368 non-Hispanic Black individuals [19.3%], and 225 non-Hispanic White individuals [11.8%] among 1908 individuals with race and ethnicity data). Within 2, 6, and 12 months of the ED visit, 45 patients (2.3%), 66 patients (3.4%), and 95 patients (5.0%) had entered shelter, respectively. For both single-item screening questions, participants who answered affirmatively had significantly higher likelihood of future shelter entry at each time point examined (eg, at 2 months: 31 participants responding yes [6.5%] vs 14 participants responding no [1.0%] to the question concerning being worried about having stable housing in the next 2 months). Sensitivity of the screening questions ranged from 0.27 to 0.69, specificity from 0.76 to 0.97, positive predictive value from 0.07 to 0.27, and area under the receiver operating characteristic curve from 0.62 to 0.72.

CONCLUSIONS AND RELEVANCE

This study found that 2 single-item screening questions assessing ED patient self-perceived risk of future housing instability and homelessness had adequate to good performance in identifying risk for future shelter entry. Such single-item screening questions should be further tested before broad adoption.

Diagnosing pulmonary thromboembolism: Concerns and controversies

Pulmonary thromboembolism (PTE) is an important cause of mortality/morbidity even today despite advancement in clinical understanding as well as diagnostic facilities. Clinical diagnosis of PTE is often challenging because of nonspecific sign/symptoms. Adherence to clinical decision-making protocols and appropriate use of diagnostic modalities like computed tomography pulmonary angiography can resolve the diagnostic dilemma in most cases and help in the overall management of PTE. This article deals with various concerns as well as controversies surrounding accurate diagnosis of PTE as on date.

Adherence to Best Practice Advice for Diagnosis of Pulmonary Embolism

PURPOSE

This study evaluated clinician adherence to the American College of Physicians Best Practice Advice for diagnosis of pulmonary embolism.

DESIGN

A prospective, single-center, descriptive design was utilized.

METHODS

A heterogeneous sample of 111 hemodynamically stable adult inpatients with a computed tomography pulmonary angiogram ordered was consented. Electronic medical records were reviewed for demographic and clinical variables to determine adherence. The 6 individual best practice statements and the overall adherence were evaluated by taking the sum of "yes" answers divided by the sample size.

RESULTS

Overall adherence was 0%. Partial adherence was observed with clinician-recorded clinical decisions rules and obtaining d-dimer (3.6% [4/111] and 10.2% [9/88], respectively) of low/intermediate probability scorers. Age adjustment of d-dimer was not recorded. Computed tomography pulmonary angiogram was the first diagnostic test in 89.7% (79/88) in low/intermediate probability patients.

CONCLUSION

In hemodynamically stable, hospitalized adults, adherence to best practice guidelines for diagnosis of pulmonary embolism was minimal. Clinical utility of the guidelines in hospitalized adults needs further evaluation. Systems problems (eg, lack of standardized orders, age-adjusted d-dimer values, information technology support) likely contributed to poor guideline adherence.

Venous thromboembolism complications in shoulder surgery: current concepts

Venous thromboembolism (VTE) is a rare yet known complication of shoulder surgery. Concerning shoulder arthroplasty, reported rates of VTE range from 0.2% to 16%. Unlike many lower extremity procedures, particularly total hip and knee arthroplasty, chemical prophylactic guidelines for VTE in shoulder surgeries have not been established. Some argue that doing so is unnecessary. On the contrary, mechanical prophylaxis is nearly universally accepted in shoulder surgery, particularly for more lengthy procedures. With limited VTE incidence in shoulder surgery, treatment is anecdotally derived from the hip and knee arthroplasty literature. Recent studies have successfully identified risk factors for VTE related to the patient and to the surgery itself. Awareness of these risk factors by the surgeon and declaration of these factors to the patient should be discussed as part of the informed consent process. Further investigational studies and larger patient cohorts will be necessary to optimise VTE prevention in shoulder surgeries.

Decision support for computed tomography in the emergency department: a multicenter cluster-randomized controlled trial

OBJECTIVES

Clinical decision support may facilitate evidence-based imaging, but most studies to date examining the impact of decision support have used non-randomized designs which limit the conclusions that can be drawn from them. This randomized trial examines if decision support can reduce computed tomography (CT) utilization for patients with mild traumatic brain injuries and suspected pulmonary embolism in the emergency department. This study was funded by a competitive public research grant and registered on ClinicalTrials.gov (NCT02410941).

METHODS

Emergency physicians at five urban sites were assigned to voluntary decision support for CT imaging of patients with either head injuries or suspected pulmonary embolism using a cluster-randomized design over a 1-year intervention period. The co-primary outcomes were CT head and CT pulmonary angiography utilization. CT pulmonary angiography diagnostic yield (proportion of studies diagnostic for acute pulmonary embolism) was a secondary outcome.

RESULTS

A total of 225 physicians were randomized and studied over a 2-year baseline and 1-year intervention period. Physicians interacted with the decision support in 38.0% and 45.0% of eligible head injury and suspected pulmonary embolism cases, respectively. A mixed effects logistic regression model demonstrated no significant impact of decision support on head CT utilization (OR 0.93, 95% CI 0.79-1.10, p = 0.31), CT pulmonary angiography utilization (OR 0.98, 95% CI 0.88-1.11, p = 0.74) or diagnostic yield (OR 1.23, 95% CI 0.96-1.65, p = 0.10). However, overall CT pulmonary diagnostic yield (17.7%) was almost three times higher than that reported by a recent large US study, suggesting that selective imaging was already being employed.

CONCLUSION

Voluntary decision support addressing many commonly cited barriers to evidence-based imaging did not significantly reduce CT utilization or improve diagnostic yield but was limited by low rates of participation and high baseline rates of selective imaging. Demonstrating value to clinicians through interventions that improve workflow is likely necessary to meaningfully change imaging practices.

Venous thromboembolism

Venous thromboembolism, comprising both deep vein thrombosis and pulmonary embolism, is a chronic illness that affects nearly 10 million people every year worldwide. Strong provoking risk factors for venous thromboembolism include major surgery and active cancer, but most events are unprovoked. Diagnosis requires a sequential work-up that combines assessment of clinical pretest probability for venous thromboembolism using a clinical score (eg, Wells score), D-dimer testing, and imaging. Venous thromboembolism can be considered excluded in patients with both a non-high clinical pretest probability and normal D-dimer concentrations. When required, ultrasonography should be done for a suspected deep vein thrombosis and CT or ventilation-perfusion scintigraphy for a suspected pulmonary embolism. Direct oral anticoagulants (DOACs) are the first-line treatment for almost all patients with venous thromboembolism (including those with cancer). After completing 3-6 months of initial treatment, anticoagulation can be discontinued in patients with venous thromboembolism provoked by a major transient risk factor. Patients whose long-term risk of recurrent venous thromboembolism outweighs the long-term risk of major bleeding, such as those with active cancer or men with unprovoked venous thromboembolism, should receive indefinite anticoagulant treatment. Pharmacological venous thromboembolism prophylaxis is generally warranted in patients undergoing major orthopaedic or cancer surgery. Ongoing research is focused on improving diagnostic strategies for suspected deep vein thrombosis, comparing different DOACs, developing safer anticoagulants, and further individualising approaches for the prevention and management of venous thromboembolism.

Contemporary management of acute pulmonary embolism

This review examines the recent progress in the initial management of pulmonary embolism (PE). Diagnostic strategies allowing the safe decrease of imaging testing have been proposed. New modalities of catheter-based interventions have emerged for hemodynamically unstable PE patients. For normotensive PE patients, direct oral anticoagulant treatment has become the new norm and a large proportion of patients are eligible for home treatment.

Risk stratification of emergency department patients with acute pulmonary thromboembolism: Is chest pain a reason to investigate?

BACKGROUND

This study aimed to risk-stratify chest pain as a presenting symptom in patients with a diagnosis of pulmonary thromboembolism (PE) to assess for any association. In addition, this study aimed to assess traditionally acknowledged PE risk factors in an Australian population.

METHODS

This was a retrospective single-centre cohort study assessing patients who presented to our emergency department during the period of 1 January 2019 to 1 January 2020. 730 consecutive patients who went on to computed tomography pulmonary angiography (CTPA) examination after presentation were included.

RESULTS

The rate of CTPA being positive in this study was 11.6% (85/730). Chest pain was associated with a non-significant reduction in the odds of PE (OR 0.774, P = 0.327). Univariate analysis showed significantly increased odds of a diagnosis of PE with presentation for leg pain/swelling (OR 6.670, P < 0.001). Multivariate analysis showed increasing age (OR 1.018, 95% CI 1.002-1.034, P = 0.024), clinical signs of a DVT (OR 3.194, 95% CI 1.803-5.657, P < 0.001) and positive D-dimer (OR 1.762, 95% CI 1.011-3.071, P = 0.046) were associated with increased odds of PE.

CONCLUSION

In this study, Emergency Department presentation with chest pain, whilst the most common reason to perform a CTPA, resulted in reduced odds with regard to the diagnosis of pulmonary thromboembolism. The use of CTPA in this setting may be rationalised according to other factors such as localised leg pain as a symptom, signs of DVT, increasing age or positive D-dimer.

Derivation and Validation of a 4-Level Clinical Pretest Probability Score for Suspected Pulmonary Embolism to Safely Decrease Imaging Testing

Importance

In patients with suspected pulmonary embolism (PE), overuse of diagnostic imaging is an important point of concern.

Objective

To derive and validate a 4-level pretest probability rule (4-Level Pulmonary Embolism Clinical Probability Score [4PEPS]) that makes it possible to rule out PE solely on clinical criteria and optimized D-dimer measurement to safely decrease imaging testing for suspected PE.

Design, Setting, and Participants

This study included consecutive outpatients suspected of having PE from US and European emergency departments. Individual data from 3 merged management studies (n = 11 114; overall prevalence of PE, 11%) were used for the derivation cohort and internal validation cohort. The external validation cohorts were taken from 2 independent studies, the first with a high PE prevalence (n = 1548; prevalence, 21.5%) and the second with a moderate PE prevalence (n = 1669; prevalence, 11.7%). A prior definition of pretest probability target values to achieve a posttest probability less than 2% was used on the basis of the negative likelihood ratios of D-dimer. Data were collected from January 2003 to April 2016, and data were analyzed from June 2018 to August 2019.

Main Outcomes and Measures

The rate of PE diagnosed during the initial workup or during follow-up and the rate of imaging testing.

Results

Of the 5588 patients in the derivation cohort, 3441 (61.8%) were female, and the mean (SD) age was 52 (18.5) years. The 4PEPS comprises 13 clinical variables scored from -2 to 5. It results in the following strategy: (1) very low probability of PE if 4PEPS is less than 0: PE ruled out without testing; (2) low probability of PE if 4PEPS is 0 to 5: PE ruled out if D-dimer level is less than 1.0 μg/mL; (3) moderate probability of PE if 4PEPS is 6 to 12: PE ruled out if D-dimer level is less than the age-adjusted cutoff value; (4) high probability of PE if 4PEPS is greater than 12: PE ruled out by imaging without preceding D-dimer test. In the first and the second external validation cohorts, the area under the receiver operator characteristic curves were 0.79 (95% CI, 0.76 to 0.82) and 0.78 (95% CI, 0.74 to 0.81), respectively. The false-negative testing rates if the 4PEPS strategy had been applied were 0.71% (95% CI, 0.37 to 1.23) and 0.89% (95% CI, 0.53 to 1.49), respectively. The absolute reductions in imaging testing were -22% (95% CI, -26 to -19) and -19% (95% CI, -22 to -16) in the first and second external validation cohorts, respectively. The 4PEPS strategy compared favorably with all recent strategies in terms of imaging testing.

Conclusions and Relevance

The 4PEPS strategy may lead to a substantial and safe reduction in imaging testing for patients with suspected PE. It should now be tested in a formal outcome study.

Suspected Acute Pulmonary Embolism: Gestalt, Scoring Systems, and Artificial Intelligence

Pulmonary embolism (PE) remains a diagnostic challenge in 2021. As the pathology is potentially fatal and signs and symptoms are nonspecific, further investigations are classically required. Based on the Bayesian approach, clinical probability became the keystone of the diagnostic strategy to rule out PE in the case of a negative testing. Several clinical probability assessment methods are validated: gestalt, the Wells score, or the revised Geneva score. While the debate persists as to the best way to assess clinical probability, its assessment allows for the good interpretation of the investigation results and therefore directs the correct diagnostic strategy. The wide availability of computed tomography pulmonary angiography (CTPA) resulted in a major increase in investigations with a moderate increase in diagnosis, without any notable improvement in patient outcomes. This leads to a new challenge for PE diagnosis which is the limitation of the number of testing for suspected PE. We review different strategies recently developed to achieve this goal. The last challenge concerns the implementation in clinical practice. Two approaches are developed: simplification of the strategies versus the use of digital support tools allowing more sophisticated strategies. Artificial intelligence with machine-learning algorithms will probably be a future tool to guide the physician in this complex approach concerning acute PE suspicion.

Utilization of serum D-dimer assays prior to computed tomography pulmonary angiography scans in the diagnosis of pulmonary embolism among emergency department physicians: a retrospective observational study

Background

A variety of evidence-based algorithms and decision rules using D-Dimer testing have been proposed as instruments to allow physicians to safely rule out a pulmonary embolism (PE) in low-risk patients.

Objective

To describe the prevalence of D-Dimer utilization among emergency department (ED) physicians and its impact on positive yields and utilization rates of Computed Tomography Pulmonary Angiography (CTPA).

Methods

Data was collected on all CTPA studies ordered by ED physicians at three sites during a 2-year period. Using a chi-square test, we compared the diagnostic yield for those patients who had a D-Dimer prior to their CTPA and those who did not. Secondary analysis was done to examine the impact of D-Dimer testing prior to CTPA on individual physician diagnostic yield or utilization rate.

Results

A total of 2811 CTPAs were included in the analysis. Of these, 964 CTPAs (34.3%) were ordered without a D-Dimer, and 343 (18.7%) underwent a CTPA despite a negative D-Dimer. Those CTPAs preceded by a D-Dimer showed no significant difference in positive yields when compared to those ordered without a D-Dimer (9.9% versus 11.3%, p = 0.26). At the individual physician level, no statistically significant relationship was found between D-Dimer utilization and CTPA utilization rate or diagnostic yield.

Conclusion

This study provides evidence of suboptimal adherence to guidelines in terms of D-Dimer screening prior to CTPA, and forgoing CTPAs in patients with negative D-Dimers. However, the lack of a positive impact of D-Dimer testing on either CTPA diagnostic yield or utilization rate is indicative of issues relating to the high false-positive rates associated with D-Dimer screening.

Recent advances in understanding, diagnosing and treating venous thrombosis

Focusing on the current state of the art, this article (a) describes recent advances in the understanding of the pathogenesis of venous thromboembolism (VTE), (b) discusses current approaches for the prevention, diagnosis and treatment of VTE, (c) outlines the role of aspirin for VTE prevention and treatment, and (d) highlights the unmet needs in VTE management and describes novel approaches to address them.

Patients with Mild COVID-19 Symptoms and Coincident Pulmonary Embolism: A Case Series

INTRODUCTION

Frequent thrombotic complications have been reported in patients with severe coronavirus disease 2019 (COVID-19) infection. The risk in patients with mild disease is unknown.

CASE REPORT

We report a case series of three individuals recently diagnosed with COVID-19, who presented to the emergency department with chest pain and were found to have pulmonary emboli. The patients had mild symptoms, no vital sign abnormalities, and were negative according to the pulmonary embolism rule-out criteria.

CONCLUSION

This suggests that patients with active or suspected COVID-19 should be considered at elevated risk for pulmonary embolism when presenting with chest pain, even without common risk factors for pulmonary embolism.

Comprehensive Outpatient Management of Low-Risk Pulmonary Embolism: Can Primary Care Do This? A Narrative Review

INTRODUCTION

The evidence for outpatient management of hemodynamically stable, low-risk patients with acute symptomatic pulmonary embolism (PE) is mounting. Guidance in identifying patients who are eligible for outpatient (ambulatory) care is available in the literature and society guidelines. Less is known about who can identify patients eligible for outpatient management and in what clinical practice settings.

OBJECTIVE

To answer the question, "Can primary care do this?" (provide comprehensive outpatient management of low-risk PE).

METHODS

We undertook a narrative review of the literature on the outpatient management of acute PE focusing on site of care. We searched the English-language literature in PubMed and Embase from January 1, 1950, through July 15, 2019.

RESULTS

We identified 26 eligible studies. We found no studies that evaluated comprehensive PE management in a primary care clinic or general practice setting. In 19 studies, the site-of-care decision making occurred in the Emergency Department (or after a short period of supplemental observation) and in 7 studies the decision occurred in a specialty clinic. We discuss the components of care involved in the diagnosis, outpatient eligibility assessment, treatment, and follow-up of ambulatory patients with acute PE.

DISCUSSION

We see no formal reason why a trained primary care physician could not provide comprehensive care for select patients with low-risk PE. Leading obstacles include lack of ready access to advanced pulmonary imaging and the time constraints of a busy outpatient clinic.

CONCLUSION

Until studies establish safe parameters of such a practice, the question "Can primary care do this?" must remain open.

A narrative review of red blood cell distribution width as a marker for pulmonary embolism

Red blood cell distribution width (RDW) is a marker of variability in red blood cell size, and is routinely reported as part of a patient's complete blood count. RDW has been shown to be associated with the prediction, severity and prognosis of pulmonary embolism (PE) in recent studies. The underlying biomolecular mechanism of the relationship of RDW to PE is largely unknown, but is thought to be due to the relationship of RDW with acute inflammatory markers and variations in blood viscosity. This review substantiates that a high RDW level, defined using either an arbitrary number or according to receiver operator curve statistics, is associated with a higher risk of acute PE, increased severity (massive vs. submassive) of PE and increased mortality in patients with PE. Nevertheless, the comparison of current studies is limited due to the definition of high RDW (each study uses a different RDW cutoff level), the broad range of exclusion criteria and the inclusion of differing modalities used to diagnose a PE (computed tomography angiogram, ventilation-perfusion study, or clinical diagnosis). Despite the above limitations, these studies provide a promising future clinical use for RDW as a marker of PE.

Clinical variables that increase the probability of pulmonary embolism diagnosis in symptomatic children

BACKGROUND

Pulmonary embolism (PE) in children carries a significant morbidity and mortality. We examined previously described factors in 2 cohorts of children tested for PE and identified novel factors.

METHODS

We combined data from 2 retrospective cohorts. Patients up to age 21 years were included who underwent imaging or D-dimer testing for PE, with positive radiologic testing being the gold standard. Combined predictor variables were examined by univariate analysis and then forward stepwise multivariable logistic regression.

RESULTS

The combined data set yielded 1103 patients with 42 unique predictor variables, and 93 PE-positive patients (8.4%), with a median age of 16 years. Univariate analysis retained 17 variables, and multivariable logistic regression found 9 significant variables with increased probability of PE diagnosis: age-adjusted tachycardia, tachypnea, hypoxia, unilateral limb swelling, trauma/surgery requiring hospitalization in previous 4 weeks, prior thromboembolism, cancer, anemia, and leukocytosis.

CONCLUSION

This combined data set of children with suspected PE discovered factors that may contribute to a diagnosis of PE: hypoxia, unilateral limb swelling, trauma/surgery requiring hospitalization in previous 4 weeks, prior thromboembolism, and cancer, age-adjusted tachycardia, tachypnea, anemia, and leukocytosis. Prospective testing is needed to determine which criteria should be used to initiate diagnostic testing for PE in children.

Variability in practice patterns among emergency physicians in the evaluation of patients with a suspected diagnosis of pulmonary embolism

PURPOSE

To describe the inter-physician variability in the utilisation rate and diagnostic yield of computed tomography pulmonary angiography (CTPA) among a group of emergency department (ED) physicians working in a similar clinical environment.

METHODS

We collected data on all CTPA studies ordered by ED physicians at three affiliated sites during a 2-year period between January 1, 2016, and December 31, 2017. For each physician, we calculated individual CTPA utilisation rate (total number of CTPAs ordered per 1000 ED visits) and diagnostic yield (percentage of CTPAs that were positive for PE). Additional analysis was carried out in order to identify the highest orderers of CTPA and their diagnostic yield.

RESULTS

Seventy-seven ED physicians who collectively ordered a total of 2788 CTPAs were included in the study. Utilisation rates ranged from 1.1 to 22.2 CTPA per 1000 ED visits (median: 5.2 CTPA/1000 ED visits; 25%ile: 3.6 CTPA/1000 ED visits; 75%ile: 7.9 CTPA/1000 ED visits) and the CTPA diagnostic yields ranged from 0% to 33% (median: 9.1%; 25%ile: 5.2%; 75%ile: 16.1%). Those physicians in the lower quartile for ordering rate had a higher mean diagnostic yield when compared to the higher quartiles.

CONCLUSION

The findings of this study demonstrate variability in CTPA ordering patterns and diagnostic yields 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.

Acute pulmonary embolism: a concise review of diagnosis and management

An acute pulmonary embolism (aPE) is characterised by occlusion of one or more pulmonary arteries. Physiological disturbance may be minimal, but often cardiac output decreases as the right ventricle attempts to overcome increased afterload. Additionally, ventilation-perfusion mismatches can develop in affected vascular beds, reducing systemic oxygenation. Incidence is reported at 50-75 per 100 000 in Australia and New Zealand, with 30-day mortality rates ranging from 0.5% to over 20%. Incidence is likely to increase with the ageing population, increased survival of patients with comorbidities that are considered risk factors and improving sensitivity of imaging techniques. Use of clinical prediction scores, such as the Wells score, has assisted in clinical decision-making and decreased unnecessary radiological investigations. However, imaging (i.e. computed tomography pulmonary angiography or ventilation-perfusion scans) is still necessary for objective diagnosis. Anti-coagulation remains the foundation of PE management. Haemodynamically unstable patients require thrombolysis unless absolutely contraindicated, while stable patients with right ventricular dysfunction or ischaemia should be aggressively anti-coagulated. Stable patients with no right ventricular dysfunction can be discharged home early with anti-coagulation and review. However, treatment should be case dependent with full consideration of the patient's clinical state. Direct oral anti-coagulants have become an alternative to vitamin K antagonists and are facilitating shorter hospital admissions. Additionally, duration of anti-coagulation must be decided by considering any provoking factors, bleeding risk and comorbid state. Patients with truly unprovoked or idiopathic PE often require indefinite treatment, while in provoked cases it is typically 3 months with some patients requiring longer periods of 6-12 months.

Clinical Probability Tools for Deep Venous Thrombosis, Pulmonary Embolism, and Bleeding

Overdiagnosis of venous thromboembolism is associated with increasing numbers of patient complications and health care burden. Multiple clinical tools exist to estimate the probability of pulmonary embolism and deep venous thrombosis. When used with d-dimer testing, these can further stratify venous thromboembolism risk to help inform the use of additional diagnostic testing. Although there are similar tools to estimate bleeding risk, these are not as well-validated and lack reliability.

Diagnosis of pulmonary embolism: Following the evidence from suspicion to certainty

Accurate, timely and cost-effective identification of pulmonary embolism remains a diagnostic challenge. This article reviews the pulmonary embolism diagnostic process with a focus on the best practice advice from the American College of Physicians. Benefits and risks of each diagnostic step are discussed. Emerging diagnostic tools, not included in the algorithm, are briefly reviewed.

Pulmonary Embolism in Children

Pulmonary embolism is an uncommon but potentially life-threatening event in children. There has been increasing awareness of pulmonary embolism in children with improved survival in children with systemic disease and advancements in diagnostic modalities. However, literature regarding pulmonary embolism in children is sparse, and thus current guidelines for management of pulmonary embolism in children are extrapolated from adult literature and remain controversial. This article reviews the background and pathophysiology of venous thromboembolism, as well as current diagnostic approach and recommended management of pulmonary embolism in children.

Safety of the Combination of PERC and YEARS Rules in Patients With Low Clinical Probability of Pulmonary Embolism: A Retrospective Analysis of Two Large European Cohorts

BACKGROUND

This study aimed to determine the failure rate of a combination of the PERC and the YEARS rules for the diagnosis of pulmonary embolism (PE) in the emergency department (ED).

METHODS

We performed a retrospective analysis of two European cohorts of emergency patients with low gestalt clinical probability of PE (PROPER and PERCEPIC). All patients we included were managed using a conventional strategy (D-dimer test, followed, if positive, by computed tomographic pulmonary angiogram (CTPA). We tested a diagnostic strategy that combined PERC and YEARS to rule out PE. The primary endpoint was a thromboembolic event diagnosed in the ED or at 3-months follow-up. Secondary endpoints included a thromboembolic event at baseline in the ED and a CTPA in the ED. Ninety-five percent confidence intervals (CIs) of proportions were calculated with the use of Wilson's continuity correction.

RESULTS

We analyzed 1,951 patients (mean ± SD age = 47 ± 18 years, 56% women) with an overall proportion of patients with PE of 3.5%. Both PERC and YEARS strategies were associated with 11 missed PE in the ED: failure rate 0.57 (95% CI = 0.32-1.02). At 3-month follow-up, the overall failure rate was 0.83% (95% CI = 0.51-1.35). Among the 503 patients who underwent a CTPA (26%), the use of the PERC-YEARS combination would have ruled out PE without CTPA in 249 patients (50% [95%CI = 45%-54%], absolute reduction 13% (95% CI = 11%-14%]).

CONCLUSION

The combination of PERC then YEARS was associated with a low risk of PE diagnostic failure and would have resulted in a relative reduction of almost half of CTPA.

Venous Thromboembolism: Advances in Diagnosis and Treatment

IMPORTANCE

Venous thromboembolism (VTE), comprising deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common and potentially fatal disease.

OBJECTIVE

To summarize the advances in diagnosis and treatment of VTE of the past 5 years.

EVIDENCE REVIEW

A systematic search was conducted in EMBASE Classic, EMBASE, Ovid MEDLINE, and other nonindexed citations using broad terms for diagnosis and treatment of VTE to find systematic reviews and meta-analyses, randomized trials, and prospective cohort studies published between January 1, 2013, and July 31, 2018. The 10th edition of the American College of Chest Physicians Antithrombotic Therapy Guidelines was screened to identify additional studies. Screening of titles, abstracts, and, subsequently, full-text articles was performed in duplicate, as well as data extraction and risk-of-bias assessment of the included articles.

FINDINGS

Thirty-two articles were included in this review. The application of an age-adjusted D-dimer threshold in patients with suspected PE has increased the number of patients in whom imaging can be withheld. The Pulmonary Embolism Rule-Out Criteria safely exclude PE when the pretest probability is low. The introduction of direct oral anticoagulants has allowed for a simplified treatment of VTE with a lower risk of bleeding regardless of etiology or extent of the VTE (except for massive PE) and has made extended secondary prevention more acceptable. Thrombolysis is best reserved for patients with massive PE or those with DVT and threatened limb loss. Insertion of inferior vena cava filters should be avoided unless anticoagulation is absolutely contraindicated in patients with recent acute VTE. Graduated compression stockings are no longer recommended to treat DVT but may be used when acute or chronic symptoms are present. Anticoagulation may no longer be indicated for patients with isolated distal DVT at low risk of recurrence.

CONCLUSIONS AND RELEVANCE

Over the past 5 years, substantial progress has been made in VTE management, allowing for diagnostic and therapeutic strategies tailored to individual patient characteristics, preferences, and values.

Retrospective validation of the pulmonary embolism rule-out criteria rule in 'PE unlikely' patients with suspected pulmonary embolism

INTRODUCTION

Patients presenting to emergency departments (EDs) with suspected pulmonary embolism (PE) can be risk stratified and those who are deemed to be at low risk for PE usually undergo D-dimer testing. A negative D-dimer in this low-risk group rules out PE with a high degree of certainty because of its high sensitivity. The D-dimer is, however, a poorly specific test and positive results often lead to unnecessary radiological imaging (notably computed tomography pulmonary angiography). The Pulmonary Embolism Rule-Out Criteria (PERC) rule has been suggested as an alternative to D-dimer testing in these patients. This study looked at whether the PERC rule could safely replace the use of D-dimer in patients suspected of PE, but deemed 'PE unlikely' by the dichotomized Wells score in a UK ED setting.

PATIENTS AND METHODS

This was a retrospective review of 986 patients with suspected PE who had a blood sample for D-dimer level taken. In patients deemed 'PE unlikely' (using the dichotomized Wells score), the diagnostic performance of the PERC rule was compared with a standard D-dimer level in the detection of PE at index presentation and up to 3 months afterwards.

RESULTS

Of the 986 patients, 940 patients were deemed 'PE unlikely' using the dichotomized Wells score. Three patients with confirmed PE would have been missed by the PERC rule compared with only one missed by the D-dimer test. In these patients, the sensitivity of the PERC rule for detecting PE was 91.4% [95% confidence interval (CI): 76.9-98.2%], with a negative likelihood ratio of 0.25 (95% CI: 0.08-0.73). However, the negative predictive value of the PERC rule was 99.1% (95% CI: 97.3-99.8%). In comparison, the sensitivity for the standard D-dimer test was 97.1% (95% CI: 85.1-99.9%), with a negative likelihood ratio of 0.04 (95% CI: 0.01-0.27). The negative predictive value for the standard D-dimer test was 99.8% (95% CI: 99.2-100%).

CONCLUSION

The PERC rule has a high negative predictive value for excluding PE in patients presenting with suspected PE to the ED. However, the PERC rule may still miss around 8% of confirmed PE in patients who are deemed 'PE unlikely' by a dichotomized Wells score. Caution is advised in using the PERC rule as a substitute for the standard D-dimer test in all these patients.

Clinical characteristics of children evaluated for suspected pulmonary embolism with D-dimer testing

BACKGROUND

We sought to determine clinical variables in children tested for suspected pulmonary embolism (PE) that predict PE+ outcome for the development of paediatric PE prediction rule.

METHODS

Data were collected by query of a laboratory database for D-dimer from January 2004 to December 2014 for a large multicentre hospital system and the radiology database for pulmonary vascular imaging in children aged 5-17. Using explicit, predefined methods, trained abstractors, determined if D-dimer was sent in the evaluation of PE and then recorded predictor data which was tested for association with PE+ outcome using univariate techniques.

RESULTS

D-dimer was ordered in 526 children for clinical suspicion of PE. Thirty-four of 526 were PE+ (6.4%, 95% CI 4.3% to 8.7%). The radiology database identified 17 additional patients with PE (n=51 PE+ total). Children evaluated for PE were primarily in the ED setting (80%), teenagers (88%) and 2:1 female:male. Children with PE had higher mean heart and higher respiratory rate and a lower pulse oximetry and haemoglobin concentration. On univariate analysis, five conditions were more frequent in PE+ compared with no PE: surgery, central line, limb immobility, prior PE or deep vein thrombosis and cancer.

CONCLUSIONS

The rate of PE diagnosis in children with D-dimer was 6.4%, similar to that seen in adults; most children with PE are over 13 years and had clinical predictors known to increase probability of PE in symptomatic adults. Future studies should use these criteria to develop a clinical decision rule for PE in children.

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.

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.

Effect of the Pulmonary Embolism Rule-Out Criteria on Subsequent Thromboembolic Events Among Low-Risk Emergency Department Patients: The PROPER Randomized Clinical Trial

IMPORTANCE

The safety of the pulmonary embolism rule-out criteria (PERC), an 8-item block of clinical criteria aimed at ruling out pulmonary embolism (PE), has not been assessed in a randomized clinical trial.

OBJECTIVE

To prospectively validate the safety of a PERC-based strategy to rule out PE.

DESIGN, SETTING, AND PATIENTS

A crossover cluster-randomized clinical noninferiority trial in 14 emergency departments in France. Patients with a low gestalt clinical probability of PE were included from August 2015 to September 2016, and followed up until December 2016.

INTERVENTIONS

Each center was randomized for the sequence of intervention periods. In the PERC period, the diagnosis of PE was excluded with no further testing if all 8 items of the PERC rule were negative.

MAIN OUTCOMES AND MEASURES

The primary end point was the occurrence of a thromboembolic event during the 3-month follow-up period that was not initially diagnosed. The noninferiority margin was set at 1.5%. Secondary end points included the rate of computed tomographic pulmonary angiography (CTPA), median length of stay in the emergency department, and rate of hospital admission.

RESULTS

Among 1916 patients who were cluster-randomized (mean age 44 years, 980 [51%] women), 962 were assigned to the PERC group and 954 were assigned to the control group. A total of 1749 patients completed the trial. A PE was diagnosed at initial presentation in 26 patients in the control group (2.7%) vs 14 (1.5%) in the PERC group (difference, 1.3% [95% CI, -0.1% to 2.7%]; P = .052). One PE (0.1%) was diagnosed during follow-up in the PERC group vs none in the control group (difference, 0.1% [95% CI, -∞ to 0.8%]). The proportion of patients undergoing CTPA in the PERC group vs control group was 13% vs 23% (difference, -10% [95% CI, -13% to -6%]; P < .001). In the PERC group, rates were significantly reduced for the median length of emergency department stay (mean reduction, 36 minutes [95% CI, 4 to 68]) and hospital admission (difference, 3.3% [95% CI, 0.1% to 6.6%]).

CONCLUSIONS AND RELEVANCE

Among very low-risk patients with suspected PE, randomization to a PERC strategy vs conventional strategy did not result in an inferior rate of thromboembolic events over 3 months. These findings support the safety of PERC for very low-risk patients presenting to the emergency department.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02375919.

Pulmonary embolism rule-out criteria (PERC) rule in European patients with low implicit clinical probability (PERCEPIC): a multicentre, prospective, observational study

BACKGROUND

The ability of the pulmonary embolism rule-out criteria (PERC) to exclude pulmonary embolism without further testing remains debated outside the USA, especially in the population with suspected pulmonary embolism who have a high prevalence of the condition. Our main objective was to prospectively assess the predictive value of negative PERC to rule out pulmonary embolism among European patients with low implicit clinical probability.

METHODS

We did a multicentre, prospective, observational study in 12 emergency departments in France and Belgium. We included consecutive patients aged 18 years or older with suspected pulmonary embolism. Patients were excluded if they had already been hospitalised for more than 2 days, had curative anticoagulant therapy in progress for more than 48 h, or had a diagnosis of thromboembolic disease documented before admission to emergency department. Physicians completed a standardised case report form comprising implicit clinical probability assessment (low, moderate, or high) and a list of risk factors including criteria of the PERC rule. They were asked to follow international recommendations for diagnostic strategy, masked to PERC assessment. The primary endpoint was the proportion of patients with low implicit clinical probability and negative PERC who had venous thromboembolic events, diagnosed during initial diagnostic work-up or during 3-month follow-up, as externally adjudicated by an independent committee masked to the PERC and clinical probability assessment. The upper limit of the 95% CI around the 3-month thromboembolic risk was set at 3%. We did all analyses by intention to treat, including all patients with complete follow-up. This trial is registered with ClinicalTrials.gov, number NCT02360540.

FINDINGS

Between May 1, 2015, and April 30, 2016, 1773 consecutive patients with suspected pulmonary embolism were prospectively assessed for inclusion, of whom 1757 were included. 1052 (60%) patients were classed as having low clinical probability, 49 (4·7%, 95% CI 3·5-6·1) of whom had a venous thromboembolic event. In patients with a low implicit clinical probability, 337 (32%) patients had negative PERC, of whom four (1·2%; 95% CI 0·4-2·9) went on to have a pulmonary embolism.

INTERPRETATION

In European patients with low implicit clinical probability, PERC can exclude pulmonary embolism with a low percentage of false-negative results. The results of our prospective, observational study allow and justify an implementation study of the PERC rule in Europe.

FUNDING

French Ministry of Health.

Impact of Patient Affect on Physician Estimate of Probability of Serious Illness and Test Ordering

PURPOSE

The authors hypothesize patient facial affect may influence clinician pretest probability (PTP) estimate of cardiopulmonary emergency (CPE) and desire to order a computerized tomographic pulmonary angiogram (CTPA).

METHOD

This prospective study was conducted at three Indiana University-affiliated hospitals in two parts: collecting videos of patients undergoing CTPA for suspected acute pulmonary embolism watching a humorous video (August 2014-April 2015) and presenting the medical histories and videos to clinicians to determine the impact of patient facial affect on physicians' PTP estimate of CPE and desire to order a CTPA (June-November 2015). Patient outcomes were adjudicated as CPE+ or CPE- by three independent reviewers. Physicians completed a standardized test of facial affect recognition, read standardized medical histories, then viewed videos of the patients' faces. Clinicians marked their PTP estimate of CPE and desire for a CTPA before and after seeing the video on a visual analog scale (VAS).

RESULTS

Fifty physicians completed all 73 videos. Seeing the patient's face produced a > 10% absolute change in PTP estimate of CPE in 1,204/3,650 (33%) cases and desire for a CTPA in 1,095/3,650 (30%) cases. The mean area under the receiver operating characteristic curve for CPE estimate was 0.55 ± 0.15, and the change in CPE VAS was negatively correlated with physicians' standardized test scores (r = -0.23).

CONCLUSIONS

Clinicians may use patients' faces to make clinically important inferences about presence of serious illness and need for diagnostic testing. However, these inferences may fail to align with actual patient outcomes.