Diagnostic accuracy of pulmonary embolism rule-out criteria: a systematic review and meta-analysis

Overuse of Computed Tomography Pulmonary Angiography and Low Utilization of Clinical Prediction Rules in Suspected Pulmonary Embolism Patients at a Regional Australian Hospital

A pulmonary embolism (PE) is an obstruction in the pulmonary arterial system and may include non-specific signs and symptoms. Clinical prediction rules (CPRs) assess the pretest probability (PTP) of a PE to prevent the overuse of computed tomography pulmonary angiography (CTPA). CTPA overuse results in patient harm and health system waste. This study aimed to evaluate CTPA usage in an Australian regional hospital through analyzing CTPA encounters. A retrospective chart analysis was undertaken of 100 CTPAs conducted at an Australian regional hospital from April to May 2023. Analysis was undertaken for parameters including risk factors, signs and symptoms, investigations, and the use of CPRs. Overall, 86% of patients had signs and/or symptoms of a PE within a week of examination, and 6% of the population had signs of deep vein thrombosis. More than half of the population had no risk factors, while the most prevalent risk factors were a recent history of immobilization/trauma and/or having surgery that required general anesthesia in the last 4 weeks. The most common co-morbidity was chronic lung disease (11%). For the pre-test diagnostic workup, the ECG was the most ordered investigation. The Wells' score was used at 10%, while most patients did not have any CPRs applied. The prevalence of PEs discovered on CTPAs was 9%. CPRs were under-utilized in this Australian regional hospital. The D-dimers for ruling out subjects with low PTP derived from CPRs were also underused. This led to the inappropriate overordering of CTPAs, resulting in negative implications for patients and unnecessary costs to the health system.

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.

High-Risk Chief Complaints I: Chest Pain-The Big Three (an Update)

Nontraumatic chest pain is a frequent concern of emergency department patients, with causes that range from benign to immediately life threatening. Identifying those patients who require immediate/urgent intervention remains challenging and is a high-risk area for emergency medicine physicians where incorrect or delayed diagnosis may lead to significant morbidity and mortality. This article focuses on the 3 most prevalent diagnoses associated with adverse outcomes in patients presenting with nontraumatic chest pain, acute coronary syndrome, thoracic aortic dissection, and pulmonary embolism. Important aspects of clinical evaluation, diagnostic testing, treatment, and disposition and other less common causes of lethal chest pain are also discussed.

Ambulatory management of pulmonary embolism

The diagnosis of pulmonary embolism can be very difficult and elusive. It depends greatly on the use of diagnostic tests, which are in turn interpreted according to a pre-test clinical probability. These include non-specific tests such as the chest X-ray and electrocardiograph, which help exclude other conditions such as pneumonia or myocardial infarction. On the other hand, more specific tests such as computed tomography or ventilation/perfusion scanning are used to confirm or exclude the diagnosis of pulmonary embolism. The condition is potentially fatal, and in the past patients with suspected pulmonary embolism constituted a significant number of hospital admissions. Despite this, the majority were found not to have pulmonary embolism. More recently, studies have suggested that most patients with suspected pulmonary embolism who are haemodynamically stable can be safely managed on an ambulatory pathway. Therefore, there is a paradigm shift towards investigating and treating pulmonary embolism in the outpatient setting. This article discusses the ambulatory pathway of the diagnosis and treatment of pulmonary embolism.

New D-dimer threshold for Japanese patients with suspected pulmonary embolism: a retrospective cohort study

Background

In the diagnosis of pulmonary embolism (PE), the d-dimer threshold is based on studies conducted in Western countries, where the incidence rate is 5 times higher than that in Asian countries, including Japan. If we could elevate the d-dimer threshold based on the low pre-test probability in the Japanese population, we could omit the computed tomography pulmonary angiography (CTPA) which might lead to radiation exposure and contrast-induced nephropathy. Therefore, we aimed to determine a new d-dimer threshold specific to Japanese individuals.

Methods

We conducted a retrospective cohort study at an emergency department in Japan, using medical charts collected from January 2013 to July 2017. We included patients whose d-dimer were measured for suspicion of PE with low or intermediate probability of PE and CTPA were performed. The primary outcome was failure rate of the new d-dimer threshold, defined as the rate of PE detected by CTPA among patients with d-dimer under the new threshold ranging from 1000 to 1500 μg/L by 100. The new d-dimer threshold was appropriate if the upper limit of 95% confidence interval of the failure rate of PE was approximately 3%.

Results

In 395 patients included, the number of patients with PE was 24 (the prevalence was 6.1%). If the d-dimer threshold was 1100 μg/L, the failure rate was 0% (0/119), the upper limit of the 95% confidence interval of the failure rate was 3.1%, and 30% (119/395) of the CTPA might be omitted.

Conclusion

The new d-dimer threshold could safely exclude PE. This result can be generalized to other Asian populations with a lower incidence of PE. Further prospective studies will be needed.

Pulmonary Embolism Testing Among Emergency Department Patients Who Are Pulmonary Embolism Rule-out Criteria Negative

OBJECTIVE

Previous studies have demonstrated that rates of pulmonary embolism (PE) testing have increased without a concomitant decrease in PE-related mortality. The Pulmonary Embolism Rule-out Criteria (PERC) intend to reduce testing for PE in the emergency department (ED) by identifying low-risk patients ("PERC-negative") who do not require D-dimer, computed tomography pulmonary angiogram (CTPA), or ventilation/perfusion (VQ) scan for PE. This study assesses PE testing rates among PERC-negative patients presenting to an urban academic ED.

METHODS

We prospectively enrolled a convenience sample of ED patients with chest pain and/or shortness of breath presenting between June 2010 and December 2015. We recorded baseline variables at the time of ED presentation, information on testing performed in the ED, and the diagnosis of acute PE during the ED visit. We classified patients as PERC-positive or PERC-negative utilizing baseline variables and clinical characteristics.

RESULTS

Of the 3,024 study patients, 54.8% (95% confidence interval = 53%-56.5%) were female and the mean age was 51.7 (51.1-52.3) years. A total of 17.5% (16.2%-18.9%) of study patients were PERC-negative and 33.7% (32%-35.4%) of all patients underwent testing for PE. A total of 25.5% (22%-29.4%) of PERC-negative patients had PE testing compared to 35.4% (33.6%-37.3%) of PERC-positive patients (p < 0.001). A total of 7.2% (5.3%-9.7%) of PERC-negative patients had advanced imaging without a D-dimer compared to 19.2% (17.8%-20.8%) of PERC-positive patients (p < 0.001). In multivariate analysis, factors associated with PE testing in PERC-negative patients included age, white non-Hispanic race/ethnicity, pleuritic chest pain, and a complaint of both chest pain and shortness of breath. Two PERC-negative patients (0.4%) were diagnosed with an acute PE in the ED compared to 2.2% of PERC-positive patients (p = 0.008). The overall testing yield for PE was 1.6% (0.4%-9.2%) among PERC-negative patients versus 6.3% (4.9%-8.1%) among PERC-positive patients (p = 0.017).

CONCLUSION

In an academic ED, a significant proportion of PERC-negative patients underwent testing for PE, including CT or VQ scan without D-dimer risk stratification. Future areas of research may include evaluating factors that lead clinicians to pursue PE testing in PERC-negative patients and implementing clinical pathways to minimize practice variability among these patients.

Embedded Clinical Decision Support in Electronic Health Record Decreases Use of High-cost Imaging in the Emergency Department: EmbED study

OBJECTIVE

The objective was to evaluate the impact of evidence-based clinical decision support tools integrated directly into provider workflow in the electronic health record on utilization of computed tomography (CT) brain, C-spine, and pulmonary embolism (PE).

METHODS

Validated, well-accepted scoring tools for head injury, C-spine injury, and PE were embedded into the electronic health record in a manner minimally disruptive to provider workflow. This was a longitudinal, before/after study in five emergency departments (EDs) in a healthcare system with a common electronic health record. Attending ED physicians practicing during the entire study period were included. The main outcome measure was proportion of CTs ordered by provider (total number of CT scans of a given type divided by total patients seen by that provider) in aggregate in the pre- and post intervention period.

RESULTS

There were 235,858 total patient visits analyzed in this study with an absolute decrease of 6,106 CT scan ordering for the three studies. Across all sites, there was greater than 6% decrease in utilization of CT brain and CT C-spine (-10%, 95% CI = -13% to -7%, p < 0.001; and -6%, 95% CI =-11% to -1%, p = 0.03, respectively). The use of CT PE also decreased but was not significant (-2%, 95% CI = -9% to +5%, p = 0.42). For all CT types, high utilizers in the pre-intervention period decreased usage over 14% in the post-intervention period with CT brain (-18%, 95% CI = -22% to -15%, p < 0.001), CT C-spine (-14%, 95% CI = -20% to -8%, p = 0.001), and CT PE (-23%, 95% CI = -31% to -14%, p < 0.001). For all three studies, the average utilizers did not change their usage practices. For CT brain, the low utilizers also did not increase usage but for CT C-spine and CT PE usage was increased (+29%, 95% CI = 10% to 52%, p = 0.003; and +46%, 95% CI = 26% to 70%, p < 0.001, respectively).

CONCLUSION

Embedded clinical decision support is associated with decreased overall utilization of high-cost imaging, especially among higher utilizers. It also affected low utilizers, increasing their usage consistent with improved adherence to guidelines, but this effect did not offset the overall decreased utilization for CT brain or CT C-spine. Thus, integrating clinical decision support into the provider workflow promotes usage of validated tools across providers, which can standardize the delivery of care and improve compliance with evidence-based guidelines.

Diagnosis of suspected venous thromboembolism

The primary goal of diagnostic testing for venous thromboembolism (VTE) is to identify all patients who could benefit from anticoagulant therapy. Test results that identify patients as having a ≤2% risk of VTE in the next 3 months are judged to exclude deep vein thrombosis (DVT) or pulmonary embolism (PE). Clinical evaluation, with assessment of: (1) clinical pretest probability (CPTP) for VTE; (2) likelihood of important alternative diagnoses; and (3) the probable yield of D-dimer and various imaging tests, guide which tests should be performed. The combination of nonhigh CPTP and negative D-dimer testing excludes DVT or PE in one-third to a half of outpatients. Venous ultrasound of the proximal veins, with or without examination of the distal veins, is the primary imaging test for leg and upper-extremity DVT. If a previous test is not available for comparison, the positive predictive value of ultrasound is low in patients with previous DVT. Computed tomography pulmonary angiography (CTPA) is the primary imaging test for PE and often yields an alternative diagnosis when there is no PE. Ventilation-perfusion scanning is associated with less radiation exposure than CTPA and is preferred in younger patients, particularly during pregnancy. If DVT or PE cannot be "ruled-in" or "ruled-out" by initial diagnostic testing, patients can usually be managed safely by: (1) withholding anticoagulant therapy; and (2) doing serial ultrasound examinations to detect new or extending DVT.

PERC rule to exclude the diagnosis of pulmonary embolism in emergency low-risk patients: study protocol for the PROPER randomized controlled study

BACKGROUND

The diagnosis of Pulmonary Embolism (PE) in the emergency department (ED) is crucial. As emergency physicians fear missing this potential life-threatening condition, PE tends to be over-investigated, exposing patients to unnecessary risks and uncertain benefit in terms of outcome. The Pulmonary Embolism Rule-out Criteria (PERC) is an eight-item block of clinical criteria that can identify patients who can safely be discharged from the ED without further investigation for PE. The endorsement of this rule could markedly reduce the number of irradiative imaging studies, ED length of stay, and rate of adverse events resulting from both diagnostic and therapeutic interventions. Several retrospective and prospective studies have shown the safety and benefits of the PERC rule for PE diagnosis in low-risk patients, but the validity of this rule is still controversial. We hypothesize that in European patients with a low gestalt clinical probability and who are PERC-negative, PE can be safely ruled out and the patient discharged without further testing.

METHODS/DESIGN

This is a controlled, cluster randomized trial, in 15 centers in France. Each center will be randomized for the sequence of intervention periods: a 6-month intervention period (PERC-based strategy) followed by a 6-month control period (usual care), or in reverse order, with 2 months of "wash-out" between the 2 periods. Adult patients presenting to the ED with a suspicion of PE and a low pre test probability estimated by clinical gestalt will be eligible. The primary outcome is the percentage of failure resulting from the diagnostic strategy, defined as diagnosed venous thromboembolic events at 3-month follow-up, among patients for whom PE has been initially ruled out.

DISCUSSION

The PERC rule has the potential to decrease the number of irradiative imaging studies in the ED, and is reported to be safe. However, no randomized study has ever validated the safety of PERC. Furthermore, some studies have challenged the safety of a PERC-based strategy to rule-out PE, especially in Europe where the prevalence of PE diagnosed in the ED is high. The PROPER study should provide high-quality evidence to settle this issue. If it confirms the safety of the PERC rule, physicians will be able to reduce the number of investigations, associated subsequent adverse events, costs, and ED length of stay for patients with a low clinical probability of PE.

TRIAL REGISTRATION

NCT02375919 .

Investigation of publication bias in meta-analyses of diagnostic test accuracy: a meta-epidemiological study

Background

The validity of a meta-analysis can be understood better in light of the possible impact of publication bias. The majority of the methods to investigate publication bias in terms of small study-effects are developed for meta-analyses of intervention studies, leaving authors of diagnostic test accuracy (DTA) systematic reviews with limited guidance. The aim of this study was to evaluate if and how publication bias was assessed in meta-analyses of DTA, and to compare the results of various statistical methods used to assess publication bias.

Methods

A systematic search was initiated to identify DTA reviews with a meta-analysis published between September 2011 and January 2012. We extracted all information about publication bias from the reviews and the two-by-two tables. Existing statistical methods for the detection of publication bias were applied on data from the included studies.

Results

Out of 1,335 references, 114 reviews could be included. Publication bias was explicitly mentioned in 75 reviews (65.8%) and 47 of these had performed statistical methods to investigate publication bias in terms of small study-effects: 6 by drawing funnel plots, 16 by statistical testing and 25 by applying both methods. The applied tests were Egger’s test (n = 18), Deeks’ test (n = 12), Begg’s test (n = 5), both the Egger and Begg tests (n = 4), and other tests (n = 2). Our own comparison of the results of Begg’s, Egger’s and Deeks’ test for 92 meta-analyses indicated that up to 34% of the results did not correspond with one another.

Conclusions

The majority of DTA review authors mention or investigate publication bias. They mainly use suboptimal methods like the Begg and Egger tests that are not developed for DTA meta-analyses. Our comparison of the Begg, Egger and Deeks tests indicated that these tests do give different results and thus are not interchangeable. Deeks’ test is recommended for DTA meta-analyses and should be preferred.

Ordering CT pulmonary angiography to exclude pulmonary embolism: defense versus evidence in the emergency room

PURPOSE

To identify reasons for ordering computed tomography pulmonary angiography (CTPA), to identify the frequency of reasons for CTPA reflecting defensive behavior and evidence-based behavior, and to identify the impact of defensive medicine and of training about diagnosing pulmonary embolism (PE) on positive results of CTPA.

METHODS

Physicians in the emergency department of a tertiary care hospital completed a questionnaire before CTPA after being trained about diagnosing PE and completing questionnaires.

RESULTS

Nine hundred patients received a CTPA during 3 years. For 328 CTPAs performed during the 1-year study period, 140 (43 %) questionnaires were completed. The most frequent reasons for ordering a CTPA were to confirm/rule out PE (93 %), elevated D-dimers (66 %), fear of missing PE (55 %), and Wells/simplified revised Geneva score (53 %). A positive answer for "fear of missing PE" was inversely associated with positive CTPA (OR 0.36, 95 % CI 0.14-0.92, p = 0.033), and "Wells/simplified revised Geneva score" was associated with positive CTPA (OR 3.28, 95 % CI 1.24-8.68, p = 0.017). The proportion of positive CTPA was higher if a questionnaire was completed, compared to the 2-year comparison period (26.4 vs. 14.5 %, OR 2.12, 95 % CI 1.36-3.29, p < 0.001). The proportion of positive CTPA was non-significantly higher during the study period than during the comparison period (19.2 vs. 14.5 %, OR 1.40, 95 % CI 0.98-2.0, p = 0.067).

CONCLUSION

Reasons for CTPA reflecting defensive behavior-such as "fear of missing PE"-were frequent, and were associated with a decreased odds of positive CTPA. Defensive behavior might be modifiable by training in using guidelines.