The accuracy of the enzyme-linked immunosorbent assay D-dimer test in the diagnosis of pulmonary embolism: a meta-analysis

Evaluation of neutrophil gelatinase-associated lipocalin (NGAL), hypoxia-induced factor-1 alpha (HIF-1α) and apelin 13 levels as new potential biomarkers for pulmonary thromboembolism: A prospective clinical study

AIM

The objective was to evaluate the serum levels of neutrophil gelatinase-associated lipocalin (NGAL), hypoxia-induced factor-1 alpha (HIF-1α), and apelin 13 in patients with acute pulmonary thromboembolism (PE) and to investigate their diagnostic and prognostic role in PE patients with different mortality risk groups.

MATERIAL AND METHODS

This study was conducted in a tertiary referral center and included 124 subjects with 94 cases of PE and 30 cases of healthy control group. All subjects were 18 years of age or older. The diagnosis of PE was done with computed tomography angiography of the thorax. After the diagnosis of acute PE, the serum levels of neutrophil gelatinase-associated lipocalin (NGAL), hypoxia-induced factor-1 alpha (HIF-1α), and apelin 13 levels were measured with a commercial enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

The median and IQR (interquartile range) age of patients and control groups were 68 (56-76) and 61.5 (56-67) years, respectively. The majority of patients with PE had risk factors (97.88 %), and only two (2.12 %) had no known risk factors. HIF-1 alpha level was found to be higher in the patient group than in the control group (p = 0.03). At the same time, the HIF-1 alpha level was found to be higher in the high mortality risk group than in the control group, low mortality risk group and intermediate-low mortality risk group (p = 0.000, 0.011, 0.002, respectively). While there was no significant difference in NGAL level between the patient group and the control group, a significant difference was observed between the mortality groups. NGAL level was found to be higher in the high mortality risk group than the control group, low mortality risk group, and medium-low mortality risk group (p = 0.001, 0.000, 0.010, respectively). Apelin 13 levels did not differ significantly in all groups.

CONCLUSION

HIF-1 alpha is a promising biomarker in distinguishing between patients and control groups and in identifying those with high mortality risk in the patient group. At the same time, NGAL can be used as a successful biomarker in determining the group with high mortality risk in cases of PE.

Life expectancy in cancer patients with pulmonary thromboembolism: From clinical prognostic biomarkers and paraclinical investigations to therapeutic approaches (Review)

Pulmonary embolisms (PEs) are obstructions of the pulmonary arteries by thrombi, which are emboli and they most frequently originate from the deep venous system of the inferior limbs. Emboli can also come from the inferior vena cava, abdominal and pelvic veins, or the upper body venous system from the right atrium or ventricle of the heart. Thrombi can form in situ inside pulmonary arteries as well. A cancer patient is at a higher risk for thromboembolic phenomena given both the oncological pathological context and also due to the associated medical or surgical treatment they receive. PE is a high-risk medical emergency that is associated with an increased risk of early mortality, with sudden death occurring in 25% of patients. The long-term presence of this condition can result in thromboembolic pulmonary hypertension. The risk of mortality, both in the acute and long-term, is dependent on the severity of the acute form, the recurrence of the embolism and the associated conditions. The majority of deaths associated with PE can be prevented by early diagnosis. The aim of the present review was to describe the various biological and cellular parameters, together with known paraclinical investigations, to assist in the rapid diagnosis of PE. Mortality in patients with PE and neoplastic conditions may be reduced by initiating anticoagulant treatment as soon as possible. PE may be the first manifestation of an underlying silent malignancy or may represent a complication of an already diagnosed malignancy. Exclusion or confirmation of the diagnosis is of utmost importance to avoid unnecessary anticoagulant treatment associated with a high risk of bleeding or to start immediate anticoagulant treatment if required.

Development of aptamer-based ELISA method for d-dimer detection

This study developed an aptamer-based enzyme-linked immunosorbent assay (ELISA) system for sensitive detection of the d -dimer molecule, which is significantly elevated in several severe diseases. Aptamers are known to have advantages, such as longer stability and usability at different temperatures and in different complex samples, over antibodies, which are generally used in traditional ELISA methods. In the present work, the aptamer-based ELISA system was capable of quantitatively determining in a wide range (100 ng/ml─10 μg/ml) and remain stable for a couple of months even under ordinary room conditions. Validation of the developed system was evaluated by spiked human serum samples with high accuracy. With more comprehensive project steps, the developed aptamer-based ELISA system could be transformed into a platform that offers a sensitive, portable, and easy-to-use tool for analyzing d -dimer molecules.

Normal D-Dimer Plasma Level in a Case of Acute Thrombosis Involving Intramuscular Gastrocnemius Vein

Venous thromboembolism (VTE) is a major cause of morbidity and mortality among hospitalized patients. Studies have reported an incidence of deep venous thrombosis to be as high as 50%, especially after craniotomy. Several factors are involved in the alteration of the specificity and sensitivity of D-dimer testing. These include symptom duration, the extent of fibrinolytic and thrombosis activity, anticoagulant therapy, comorbidity associated with medical or surgical illness, cancer, inflammatory diseases, old age, postpartum, and pregnancy period, as well as previous VTE. Several studies have shown the high sensitivity of the D-dimer test (>95%) in pulmonary embolism or acute deep venous thrombosis. The cut-off value is usually within the 500 µg FEU/L range, ruling out acute VTE, especially in patients with low or intermediate clinical probability. Patients who present with a high D-dimer level may necessitate an intense diagnostic approach, the pretest probability notwithstanding. Herein, we present a case of a 52-year-old male patient who presented with a normal D-dimer level in deep venous thrombosis.

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.

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.

Doppler ultrasound and D-dimer

The diagnosis of venous thromboembolism has evolved considerably with the development of standardized diagnostic algorithms that include clinical probability assessment, D-dimer measurement and the use of non-invasive imaging modalities such as compression ultrasonography and computed tomography angiography. The implementation of these strategies aims to improve resource allocation and patient outcome. The judicious use of these diagnostic tools requires a thorough knowledge of the appropriate clinical setting in which every test and strategy is efficient and can be used safely. For this purpose, D-dimer measurement and compression ultrasonography are complementary: the former is mainly used to exclude VTE in selected patients, while the latter is used to confirm the presence of an underlying DVT.

This review provides an appraisal of the features and use of D-dimer and compression ultrasonography in the context of suspected venous thromboembolism.

Screening for Pulmonary Embolism with a D-Dimer Assay: Do we Still Need to Assess Clinical Probability as Well?

Clinical risk stratification and D-dimer assay can be of use in excluding pulmonary embolism in patients presenting to emergency departments but many D-dimer assays exist and their accuracy varies. We used clinical risk stratification combined with a quantitative latex-agglutination D-dimer assay to screen patients before arranging further imaging if required. Retrospective analysis of a sequential series of 376 patients revealed that no patient with a D-dimer of <275 ng/mL was diagnosed with pulmonary embolism, irrespective of clinical probability. We conclude that a latex-agglutination assay could be used to exclude pulmonary embolism without the necessity for clinical risk stratification. If these findings are borne out by further work, D-dimer strategies to exclude pulmonary embolism could substantially reduce imaging workload.

An Intact Dissecting Baker's Cyst Mimicking Recurrent Deep Vein Thrombosis

We report a case of a 75-year-old female with a history of acute deep vein thrombosis (DVT) 6 years ago who presented with unilateral calf swelling and pain. D-dimer was normal, and compression ultrasound revealed findings typical of DVT, including an incompressible dilated and hypoechoic peroneal vein. Despite 4 months of anticoagulation for supposed recurrent DVT, pain symptoms persisted and repeat D-dimer and compression ultrasound were unchanged. A magnetic resonance imaging scan to investigate the leg demonstrated a 6-cm dissecting Baker's cyst extending posterolaterally resulting in venous compression and distal dilation, which appeared to have been confused with a DVT. Ultrasound-guided aspiration of the cyst provided immediate and sustained relief. Herein we provide a review of the literature for the management of this rare scenario.

Is Serum Cystatin C a Predictor of Acute Pulmonary Thromboembolism in Patients With Normal Renal Function?

Early diagnosis is the key point in the management of acute pulmonary thromboembolism (PTE). There are no reports in the literature comparing the serum cystatin C levels in patients with acute PTE and normal volunteers. Therefore, in this study, we analyzed 50 patients with acute PTE and 45 healthy volunteers with normal renal function. The serum cystatin C level was significantly higher in the PTE group than in the non-PTE group (1.08 mg/dL [interquantile range (IQR) 0.79-1.56] and 0.85 mg/dL [IQR 0.77-1.03], respectively, P = .017). When determining the presence of PTE, the highest value of sensitivity and specificity was set at a cutoff value of 1.15 mg/dL with 93.3% specificity, 46.0% sensitivity, 88.5% positive predictive value, and 60.9% negative predictive value. In the multivariate model, cystatin C was significantly associated with the presence of PTE (odds ratio: 12.34, 95% CI 2.64-57.75). In conclusion, cystatin C may be an indicator of acute PTE in patients with normal renal function.

The role of ischemia modified albumin in acute pulmonary embolism

Background:

Acute pulmonary embolism (PE) is a life-threatening and a relatively common cardiovascular pathology. Although the pathogenesis of PE is well defined, there is no ideal diagnostic biochemical marker. Previous studies showed an increased ischemia modified albumin (IMA) levels in acute PE; however, the relationship between IMA and right ventricular (RV) dysfunction has not been examined. The aim of this study was to evaluate the diagnostic value of IMA and the relationship with RV dysfunction in acute PE.

MATERIALS AND METHODS:

A total of 145 patients (70 females) with suspected acute PE was enrolled to the study. Eighty-nine patients were diagnosed with acute PE via computed tomographic pulmonary angiography. Sixty-five patients with similar demographic and clinical characteristics were assigned to the control group. All patients were evaluated for RV dysfunction using transthoracic echocardiography.

Results:

Serum IMA levels were significantly increased in acute PE compared with control group (0.41 ± 0.06 vs. 0.34 ± 0.11, P = 0.001). There was no relationship between serum IMA levels and RV dysfunction. IMA levels were positively correlated with shock index and heart rate. Receiver operating curve analysis demonstrated that serum IMA levels higher than 0.4 put the diagnosis at sensitivity of 53.85% and at specificity of 85.96%.

Conclusions:

Although IMA levels are increased in patients with acute PE, it failed to predict RV dysfunction.

Effectiveness of d-dimer as a screening test for venous thromboembolism: an update

Venous thromboembolism (VTE) is the leading cause of morbidity and mortality among hospitalized patients. We searched the PubMed database and reviewed the articles published until June 2011. Articles related to the D-dimer and VTE were considered to write this paper. Many factors play a key role in changing the sensitivity and specificity of D-dimer testing, including the extent of thrombosis and fibrinolytic activity, duration of symptoms, anticoagulant therapy, comorbidity due to surgical or medical illnesses, inflammatory diseases, cancer, elderly age, pregnancy and the postpartum period, and previous VTE. Many previous studies have shown that the D-dimer test is highly sensitive (>95%) in acute deep venous thrombosis or pulmonary embolism, usually with a cut-off value of 500 μg FEU/l, which reasonably rules out acute VTE, particularly in patients with low clinical probability (LCP) or intermediate clinical probability. Patients with high D-dimer levels upon presentation may prompt a more intense diagnostic approach, irrespective of pretest probability. Studies performed after a negative D-dimer for 3 months proved the high negative predictive value (NPV) of D-dimer testing together with LCP in patients with suspected VTE. Among oncology patients, D-dimer testing has the highest sensitivity and NPV in excluding VTE. The new cutoff values of D-dimer testing were analyzed in a recent prospective study of pregnant women; they are 286 ng DDU/ml, 457 ng DDU/ml, and 644 ng DDU/ml for the first, second, and third trimesters, respectively.

Impact of d-Dimers on the Differential Diagnosis of Acute Chest Pain: Current Aspects Besides the Widely Known

d-dimers are cleavage products of fibrin that occur during plasmin-mediated fibrinolysis of blood clots. In the emergency department, d-dimer measurement represents a valuable and cost-effective tool in the differential diagnosis of acute chest pain including the main life-threatening entities: acute coronary syndrome, pulmonary embolism, and acute aortic syndrome. Whereas the diagnostic and prognostic values of d-dimer testing in acute coronary syndrome is of less priority, increases of d-dimers are frequently found in venous thromboembolism and acute aortic syndromes, especially acute aortic dissection. As to the high negative predictive value of d-dimer in those disorders, patients with low to intermediate pretest probability may profit in terms of less necessity of further non-invasive or even invasive imaging, simultaneously reducing potential complications and healthcare-related costs. However, because of the low specificity of the different d-dimer tests in contrast to its frequent usage, adequate interpretation is required. Age-related adjustment of d-dimer levels may be used to increase its diagnostic power.

Systematic review and meta-analysis of pregnant patients investigated for suspected pulmonary embolism in the emergency department

OBJECTIVES

Pregnancy causes a small increase in risk of venous thromboembolism (VTE), but a large increase in concern upon presentation to an emergency department (ED) with symptoms of pulmonary embolism (PE), which may cause physicians to employ a low test threshold. This was a systematic review with the hypothesis that symptomatic pregnant patients in the ED have a low relative risk (RR) for VTE outcome.

METHODS

Studies in all languages were identified by structured search of PubMed, EMBASE, the Cochrane library, and bibliographies in February 2014. Papers with ED patients evaluated for possible PE that included pregnancy status, and had adequate reference standards, were included. An outcome of VTE (either deep venous thrombosis [DVT] or PE) was considered disease-positive (VTE+). Papers were assessed for selection and publication bias, and heterogeneity (I(2) ). The random effects model was used if I(2)  > 24%.

RESULTS

Seventeen full-length studies of 25,339 patients were analyzed. Pooled data showed I² = 0% with a symmetrical funnel plot. Two small studies with less than 1% of all patients had evidence of selection bias. The frequency of VTE+ rate among the 506 pregnant patients was 4.1% (95% confidence interval [CI] = 2.6% to 6.0%), compared with 12.4% (95% CI = 9.0% to 16.3%) among nonpregnant patients. The pooled RR of pregnancy for VTE+ diagnosis was 0.60 (95% CI = 0.41 to 0.87). Patients in the third trimester had a RR of 0.85 (95% CI = 0.40 to 1.77), and patients of childbearing age (≤45 years) had a RR of 0.56 (95% CI = 0.34 to 0.93).

CONCLUSIONS

In the ED setting, physicians test for PE in pregnant patients at a low threshold, resulting in a low rate of VTE diagnosis and a RR of VTE that is lower than that for nonpregnant women of childbearing age who are tested for PE in the ED setting.

DIC score in pregnant women--a population based modification of the International Society on Thrombosis and Hemostasis score

Objectives

The objectives of this study were: 1) To determine the component needed to generate a validated DIC score during pregnancy. 2) To validate such scoring system in the identification of patients with clinical diagnosis of DIC.

Material and Methods

This is a population based retrospective study, including all women who gave birth at the ‘Soroka University Medical Center’ during the study period, and have had blood coagulation tests including complete blood cell count, prothrombin time (PT)(seconds), partial thromboplastin time (aPTT), fibrinogen, and D-dimers. Nomograms for pregnancy were established, and DIC score was constructed based on ROC curve analyses.

Results

1) maternal plasma fibrinogen concentrations increased during pregnancy; 2) maternal platelet count decreased gradually during gestation; 3) the PT and PTT values did not change with advancing gestation; 4) PT difference had an area under the curve (AUC) of 0.96 (p<0.001), and a PT difference ≥1.55 had an 87% sensitivity and 90% specificity for the diagnosis of DIC; 5) the platelet count had an AUC of 0.87 (p<0.001), an 86% sensitivity and 71% specificity for the diagnosis of DIC; 6) fibrinogen concentrations had an AUC of 0.95 (p<0.001) and a cutoff point ≤3.9 g/L had a sensitivity of 87% and a specificity of 92% for the development of DIC; and 7) The pregnancy adjusted DIC score had an AUC of 0.975 (p<0.001) and at a cutoff point of ≥26 had a sensitivity of 88%, a specificity of 96%, a LR(+) of 22 and a LR(−) of 0.125 for the diagnosis of DIC.

Conclusion

We could establish a sensitive and specific pregnancy adjusted DIC score. The positive likelihood ratio of this score suggests that a patient with a score of ≥26 has a high probability to have DIC.

Use of heparin in aortic dissection: beware the misdiagnosis of acute pulmonary embolism

We present a case which highlights the diagnostic difficulties between a Stanford type A aortic dissection (AD) and a pulmonary embolism (PE) and the impact it has on subsequent management. A 75-year-old man presenting with chest pain, shortness of breath and dizziness was initially suspected of having a PE and started on low-molecular-weight-heparin (LMWH). The patient was correctly diagnosed afterwards with CT of the chest to have an aortic dissection. The detrimental use of LMWH may have caused a propagation of the dissection and delayed surgical intervention of an acutely life-threatening condition. When the diagnosis is unclear, the early use of CT can help differentiate AD from PE. This in-turn can guide the management as well as the use of LMWH, which should be avoided until the correct diagnosis is confirmed.

Circulating miRNAs as sensitive and specific biomarkers for the diagnosis and monitoring of human diseases: promises and challenges

The regulation and modulation of gene expression has been a central focus of modern biomedical research ever since the first molecular elucidation of DNA. The cellular mechanisms by which genes are expressed and repressed hold valuable insight for maintaining tissue homeostasis or conversely provide mechanistic understanding of disease progression. Hence, the discovery of the first miRNA in humans roughly a decade ago profoundly shook the previously established dogmas of gene regulation. Since, these small RNAs of around 20 nucleotides have unquestionably influenced almost every area of medical research. This momentum has now spread to the clinical arena. Hundreds of papers have already been published shedding light on the mechanisms of action of miRNAs, their profound stability in almost every bodily fluid and relating their presence to disease state and severity of disease progression. In this review, we explore the diagnostic potential of miRNAs in the clinical laboratory with a focus on studies reporting the detection of miRNAs in blood and urine for investigation of human disease. Sensitivities, specificities, areas under the curve, group descriptions and miRNAs of interest for 69 studies covering a broad range of diseases are provided. We discuss the practicality of miRNAs in the screening, diagnosis and prognosis of a range of pathologies. Characteristics and pitfalls of miRNA detection in blood are also discussed. The topics covered here are pertinent in the design of future miRNA-based detection strategies for use in clinical biochemistry laboratory settings.

Evaluation of plasma D-dimer plus fibrinogen in predicting acute CVST

BACKGROUND

Prompt diagnosis of cerebral venous sinus thrombosis is a challenge owing in part to its complex and non-specific early clinical symptoms.

OBJECTIVE

This study aims to evaluate the value of clinically useful biomarkers (d-dimer and fibrinogen) for cerebral venous sinus thrombosis prediction.

METHODS

Two-hundred and thirty-three suspected cerebral venous sinus thrombosis patients were enrolled in this prospective study. Thirty-four cases confirmed as cerebral venous sinus thrombosis using imaging modalities, whereas the other 199 cases served as mimic controls. Plasma samples of 34 healthy controls were further collected from age- and gender-matched volunteers. d-dimer and fibrinogen levels of all patients and controls were measured before imaging and treatment. The dynamic d-dimer and fibrinogen levels in cerebral venous sinus thrombosis cases after anticoagulation were monitored for up to 180 consecutive days.

RESULTS

At admission before treatment the average d-dimer and fibrinogen levels in cerebral venous sinus thrombosis group were 968·9 ± 160·1 μg/l and 6·9 ± 1·3 g/l, both of which were significantly elevated when compared with that of the controls. In cerebral venous sinus thrombosis patients, 94·1% had d-dimer elevation, 73·5% had fibrinogen elevation, and 67·6% had both elevated d-dimer and fibrinogen. During acute phase, the sensitivity and specificity of predicting cerebral venous sinus thrombosis using only d-dimer were 94·1% and 97·5%, whereas that of d-dimer in combination with fibrinogen were 67·6% and 98·9%. After administering anticoagulation, d-dimer levels gradually recovered; however, fibrinogen levels fluctuated with 33·3% of the patients still exhibiting elevated values up until 180 days.

CONCLUSIONS

d-dimer may serve as an important screening tool to determine the urgency of obtaining magnetic resonance imaging/magnetic resonance venography or digital subtraction angiography in patients presenting with clinical symptoms that are suspected of cerebral venous sinus thrombosis. Furthermore, d-dimer in combination with fibrinogen may increase the predictive value of acute cerebral venous sinus thrombosis.

Clinical differences between acute CVST and non-thrombotic CVSS

BACKGROUND

Cerebral venous sinus thrombosis (CVST) is a rare stroke subtype, which has many overlapping symptoms with non-thrombotic cerebral venous sinus stenosis (CVSS) in the acute phase. Despite these similarities, their therapeutic regimens and outcomes are entirely different, and treatment delay is life-threatening. This study aims to address their clinical differences to help promote proper patient care.

METHODS

34 cases of CVST and 34 cases of non-thrombotic CVSS diagnosed with digital subtraction angiography (DSA) in the acute phase (symptoms onset within 7days) were consecutively enrolled in this prospective non-randomized and controlled study. Differences between CVST and CVSS in their clinical manifestation, plasma biomarkers, and MR or DSA imaging were compared.

RESULTS

CVST and CVSS overlap in many ways, but differ in their respective medical histories and neurological deficits. However, 20.6% of CVST and 64.7% of CVSS occur without a definitive medical history, and 70.6% of CVST and 64.7% of CVSS occur without focal neurologic deficits. In the acute phase of CVST, d-dimer and fibrinogen are found to be abnormally elevated in 94.1% and 73.5% of cases, respectively. In the CVSS group, d-dimer and fibrinogen are only elevated in 17.6% and 5.9% of cases, respectively (binary logistic regressions test, all P<0.001). In the CVST group, the predominant features in MRI/MRV and DSA imaging include local brain lesions, flow void signal loss, non-visualization, and a local filling defect sign at the involved sinus. Conversely, in the CVSS group, imaging revealed symmetrically small bilateral ventricles and the spread of cerebral edema in MRI/MRV. DSA imaging in the CVSS group revealed external compression and a narrow sinus with disproportionate venous engorgement. Despite these findings, positive imaging only appears in a minority of patients in the two groups during the acute phase (Table 4).

CONCLUSIONS

DSA may be beneficial to diagnose CVST in ambiguous patients suspected to have either CVST or CVSS. Clinically useful biomarkers (d-dimer and fibrinogen) may predict CVST in the emergency room in the ambiguous patients with or without equivocal MRI/MRV imaging.

Pulmonary embolism

Pulmonary embolism (PE) remains one of the most challenging medical diseases in the emergency department. PE is a potentially life threatening diagnosis that is seen in patients with chest pain and/or dyspnea but can span the clinical spectrum of medical presentations. In addition, it does not have any particular clinical feature, laboratory test, or diagnostic modality that can independently and confidently exclude its possibility. This article offers a review of PE in the emergency department. It emphasizes the appropriate determination of pretest probability, the approach to diagnosis and management, and special considerations related to pregnancy and radiation exposure.

Novel high-sensitive D-dimer determination predicts chemotherapy-associated venous thromboembolism in intermediate risk lung cancer patients

INTRODUCTION

We hypothesized that the use of a novel high sensitivity (HS) assay for D-dimer determination might ameliorate venous thromboembolism (VTE) risk prediction in intermediate risk lung cancer patients in whom chemotherapy could act as a trigger for VTE onset.

PATIENTS AND METHODS

Pretreatment HS D-dimer levels were retrospectively evaluated in 108 lung cancer outpatients using a novel automated latex enhanced turbidimetric immunoassay. All patients were at the start of a new platinum-based chemotherapy regimen and were classified as intermediate risk according to Khorana's assessment model. Patients were followed-up for a median period of 6.9 months.

RESULTS

Receiver operating characteristic (ROC) curves and corresponding Bayesian analysis showed that the best performance was obtained at a cutoff level of 1500 ng/mL, which resulted in a sensitivity of 81%, a specificity of 69%, a positive predictive value (PPV) of 31%, a negative predictive value (NPV) of 96%, and an accuracy of 70%. Patients with HS D-dimer levels above the cutoff had a worse VTE-free survival (60%) compared with those with levels below the cutoff (95%; P = .0001). Multivariate Cox proportional hazards survival analysis confirmed that pretreatment HS D-dimer levels were able to significantly predict VTE with a hazard ratio of 11 (95% confidence interval, 2.62-46.2; P = .001), independently of classic VTE risk factors.

CONCLUSIONS

The use of HS D-dimer determination prior to chemotherapy might allow for VTE risk stratification of intermediate risk cancer patients, helping in identifying those individuals who could benefit from thromboprophylaxis.

Critical issues in the evaluation and management of adult patients presenting to the emergency department with suspected pulmonary embolism

This clinical policy from the American College of Emergency Physicians is the revision of a 2003 clinical policy on the evaluation and management of adult patients presenting with suspected pulmonary embolism (PE).(1) A writing subcommittee reviewed the literature to derive evidence-based recommendations to help clinicians answer the following critical questions: (1) Do objective criteria provide improved risk stratification over gestalt clinical assessment in the evaluation of patients with possible PE? (2) What is the utility of the Pulmonary Embolism Rule-out Criteria (PERC) in the evaluation of patients with suspected PE? (3)What is the role of quantitative D-dimer testing in the exclusion of PE? (4) What is the role of computed tomography pulmonary angiogram of the chest as the sole diagnostic test in the exclusion of PE? (5) What is the role of venous imaging in the evaluation of patients with suspected PE? (6) What are the indications for thrombolytic therapy in patients with PE? Evidence was graded and recommendations were given based on the strength of the available data in the medical literature.

[Association of location of deep venous thrombosis and d-dimer value in acute intracerebral hemorrhage]

AIM

We investigated the association of the presence and the location of deep venous thrombosis (DVT) with D-dimer value in acute intracerebral hemorrhage (ICH).

METHODS

We analyzed the data regarding DVT in patients with ICH. Based on an ultrasonographic examination 2 weeks after the occurrence of ICH, the patients were divided according to the presence/absence and the location of DVT, i.e. no evidence of DVT (n-DVT), calf DVT (c-DVT), and proximal DVT (p-DVT). D-dimer value was measured 2 weeks later and compared among the groups.

RESULTS

The numbers of patients with n-DVT, c-DVT and p-DVT were 27, 19, and 2, respectively. Univariate analysis indicated that D-dimer values were significantly different between patients with n-DVT and c-DVT and between patients with n-DVT and p-DVT (p<0.05, respectively). The cut-off value for estimating the presence of DVT and p-DVT was 3.9 µg/mL and 18.5 µg/mL, respectively.

CONCLUSION

D-dimer value assessment after 2 weeks may be associated with the presence and the location of DVT in patients with ICH.

Re-elevation of D-dimer as a predictor of re-dissection and venous thromboembolism after Stanford type B acute aortic dissection

D-dimer measurement is a useful complementary initial diagnostic marker in patients with acute aortic dissection (AAD). However, it has not been clarified whether serial measurements of D-dimer are useful during in-hospital management of Stanford type B AAD. We studied 30 patients who were admitted with diagnosis of Stanford type B AAD and treated conservatively. D-dimer was serially measured on admission and then every 5 days during hospitalization. Patients were divided into two groups according to the presence or absence of re-elevation of D-dimer during hospitalization, in which D-dimer transition were biphasic and latter peak >10.0 μg/ml. Re-elevation of D-dimer was observed in 17 patients. There were no differences in atherosclerotic risk factors, blood pressure on admission, D-dimer level on admission, extent of AAD, and false lumen patency. Patients with re-elevation of D-dimer showed higher incidence of re-dissection and/or venous thromboembolism (VTE). Peak D-dimer level in patients with re-dissection and/or VTE was significantly higher than that without these complications (p = 0.005). In conclusion, serial measurements of D-dimer are useful for early detection of re-dissection or VTE in patients with Stanford type B AAD, which may contribute to the prevention of disastrous consequences such as pulmonary embolism and extension of AAD.

Risk of venous thromboembolism in patients with borderline quantitative D-dimer levels

OBJECTIVE

The lower threshold for D-dimer in evaluating patients with low clinical risk of venous thromboembolism (VTE) ranges from 200 to 500 ng/mL. We compared the rates of VTE in patients based on D-dimer values. We hypothesized that the rate of VTE in low-risk patients with D-dimer levels less than 500 would be less than 1%.

METHODS

STUDY DESIGN

This was a retrospective chart review:

SETTING

The study was performed in a academic, suburban emergency department (ED).

SUBJECTS

Emergency department patients with suspected VTE and D-dimer obtained were included in the study. D-dimer assay: The D-dimer assay is a quantitative instrumentation latex suspension of plasma specimens.

OUTCOMES

Presence of VTE within 30 days of ED visit.

DATA ANALYSIS

Assuming a 0% event rate in patients with D-dimer levels between 200 and 500 ng/mL, a sample of 450 patients would result in a 95% confidence interval upper limit of 0.6%.

RESULTS

There were 1270 ED patients with suspected VTE in which D-dimer levels were performed between October 2005 and October 2006. Patient mean age was 47.8 +/- 19.3 years; 63.2% were female, 78.2% were white. Of all D-dimer levels, 497 (39.1%) were less than 200 ng/mL, 479 (37.7%) were between 200 and 500 microg/mL, and 294 (23.1%) were greater than 500 ng/mL. There were no VTE events diagnosed in any of the patients with D-dimer levels less than 200 ng/mL. Four patients with D-dimer levels between 200 and 500 microg/mL had a pulmonary embolism on computed tomography angiography. Of these 4 patients, 3 had moderate clinical risk based on Well's criteria and one had a false-positive computed tomography. There were no cases of VTE in the remaining 475 patients (0%; 95% confidence interval 0%-0.6%).

CONCLUSION

The rate of confirmed VTE in low-risk patients with D-dimer levels between 200 and 500 ng/mL is very low. Low-risk patients with suspected VTE with D-dimer levels less than 500 ng/mL might not require additional testing.

High-risk chief complaints I: chest pain--the big three

Chest pain is one of the most frequently seen chief complaints in patients presenting to emergency departments, and is considered to be a "high-risk" chief complaint. The differential diagnosis for chest pain is broad, and potential causes range from the benign to the immediately life-threatening. Although many (if not most) emergency department patients with chest pain do not have an immediately life-threatening condition, correct diagnoses can be difficult to make, incorrect diagnoses may lead to catastrophic therapies, and failure to make a timely diagnosis may contribute to significant morbidity and mortality. Several atraumatic "high-risk" causes of chest pain are discussed in this article, including myocardial infarction and ischemia, thoracic aortic dissection, and pulmonary embolism. Also included are brief discussions of tension pneumothorax, esophageal perforation, and cardiac tamponade.

Implementation of a rapid whole blood D-dimer test in the emergency department of an urban academic medical center: impact on ED length of stay and ancillary test utilization

Overcrowding and prolonged patient length-of-stay (LOS) in emergency departments (EDs) are growing problems. We evaluated the impact of implementing a rapid whole blood quantitative D-dimer test (Biosite Triage, Biosite Diagnostics, San Diego, CA) in our ED satellite laboratory on 252 patients before vs 211 patients after implementation. All patients also underwent testing with the existing central laboratory method (VIDAS D-dimer, bioMérieux, Durham, NC). D-dimer turnaround time (from blood draw to result) decreased approximately 79% (approximately 2 hours vs 25 minutes). The mean ED LOS declined from 8.46 to 7.14 hours (P = .016). Hospital admissions decreased 13.8%, ED discharges increased 7.3%, and the number of patients admitted for observation increased 6.4% (P = .005). No difference in the utilization of radiologic studies was observed (P = .86). At 3 months' follow-up, none of the after-implementation patients with negative D-dimer results were admitted for subsequent venous thromboembolic disease. The rapid D-dimer test was associated with a shorter ED LOS and fewer hospital admissions.

Multicenter evaluation of a new quantitative highly sensitive D-dimer assay, the Hemosil D-dimer HS 500, in patients with clinically suspected venous thromboembolism

INTRODUCTION

D-dimer testing is widely used in conjunction with clinical pretest probability (PTP) for venous thromboembolism (VTE) exclusion. We report on a multicenter evaluation of a new, automated, latex enhanced turbidimetric immunoassay [HemosIL D-Dimer HS 500, Instrumentation Laboratory (IL)].

MATERIALS AND METHODS

747 consecutive outpatients with suspected proximal deep vein thrombosis (DVT, n=401) or pulmonary embolism (PE, n=346) were evaluated at four university hospitals in a management study with a 3 month follow-up. Samples were tested at each center using the new D-dimer assay on an automated coagulation analyzer [ACL TOP (IL)], with clinical cut-off for VTE at 500 ng/mL (FEU).

RESULTS

The sensitivity and negative predictive value (NPV) were 100% for all PTP subgroups (no false negative results); for both sensitivity and NPV the lower limit of the 95% CI in patients with moderate/low PTP was higher than 95%. The overall specificity was 45.1% (95%CI: 41.1-49.3%). Higher specificity value was recorded in the low PTP subgroup [49.2% (95%CI: 41.7-56.7)]. No significant differences were found between patients suspected of having DVT or PE; sensitivity and NPV were 100%. The reproducibility of the assay was good, being the total CVs% less than 10% for D-dimer concentration near the clinical cut-off.

CONCLUSIONS

The new, highly sensitive D-dimer assay proved to be accurate when used for VTE diagnostic work-up in outpatients. Based on 100% sensitivity and NPV and lower limit of the 95% CI higher than 95%, the assay can be used as a stand-alone test in patients with non high PTP.

Potential impact of adjusting the threshold of the quantitative D-dimer based on pretest probability of acute pulmonary embolism

OBJECTIVES

The utility of D-dimer testing for suspected pulmonary embolism (PE) can be limited by test specificity. The authors tested if the threshold of the quantitative D-dimer can be varied according to pretest probability (PTP) of PE to increase specificity while maintaining a negative predictive value (NPV) of >99%.

METHODS

This was a prospective, observational multicenter study of emergency department (ED) patients in the United States. Eligible patients had a diagnostic study ordered to evaluate possible PE. PTP was determined by the clinician's unstructured estimate and the Wells score. Five different D-dimer assays were used. D-dimer test performance was measured using 1) standard thresholds and 2) variable threshold values: twice (for low PTP patients), equal (intermediate PTP patients), or half (high PTP patients) of standard threshold. Venous thromboembolism (VTE) within 45 days required positive imaging plus decision to treat.

RESULTS

The authors enrolled 7,940 patients tested for PE, and clinicians ordered a quantitative D-dimer for 4,357 (55%) patients who had PTPs distributed as follows: low (74%), moderate (21%), or high (4%). At standard cutoffs, across all PTP strata, quantitative D-dimer testing had a test sensitivity of 94% (95% confidence interval [CI] = 91% to 97%), specificity of 58% (95% CI = 56% to 60%), and NPV of 99.5% (95% CI = 99.1% to 99.7%). If variable cutoffs had been used the overall sensitivity would have been 88% (95% CI = 83% to 92%), specificity 75% (95% CI = 74% to 76%), and NPV 99.1% (95% CI = 98.7% to 99.4%).

CONCLUSIONS

This large multicenter observational sample demonstrates that emergency medicine clinicians currently order a D-dimer in the majority of patients tested for PE, including a large proportion with intermediate PTP and high PTP. Varying the D-dimer's cutoff according to PTP can increase specificity with no measurable decrease in NPV.

The use of D-dimer testing and Wells score in patients with high probability for acute pulmonary embolism

RATIONALE, AIMS AND OBJECTIVE

To investigate if a combination of Wells pre-test probability score and D-dimer testing could be used as a safe base for making clinical decisions on further investigations for patients with intermediate to high risks of pulmonary embolism (PE).

METHODS

One hundred and twenty patients with signs or symptoms of acute PE were investigated with pulmonary angiography (PA) or contrast enhanced computed tomography of the pulmonary arteries (CTPA), D-dimer testing (Tinaquant) and clinical scoring using the Wells pre-test probability score during their first 48 hours at the hospital. Patients were recruited consecutively from emergency departments at two teaching hospitals.

RESULTS

The cut-off value of 0.5 mg L(-1) in D-dimer analysis is proved adequate with a negative predictive value (NPV) of 92% in this group of patients with intermediate to high risks. The combination of D-dimer testing and Wells score increases the NPV to 94%. The specificities of both tests were low.

CONCLUSION

D-dimer and Wells pre-test probability scores are safe to rule out acute PE even in patients with at least an intermediate risk of PE, but the specificity is low. D-dimer testing had a higher NPV than Wells score and the combination improved the algorithm further. The cut-off level for a high risk of PE measured with the Wells score was four and it seems reasonable to use that cut-off level in future algorithms. In addition, both PA and CTPA can present false positive and negative results difficult to interpret.

Comparison of the clinical usefulness of two quantitative D-Dimer tests in patients with a low clinical probability of pulmonary embolism

BACKGROUND

Quantitative D-Dimer tests are established methods in the non-invasive diagnostic management to rule out venous thromboembolism (VTE). The diagnostic performance and the clinical efficiency different D-Dimer assays in the exclusion of pulmonary embolism (PE) have not yet been compared in a clinical outcome study.

OBJECTIVE

Evaluation of the efficiency and safety of excluding the diagnosis of PE with two different quantitative D-Dimer assays in consecutive patients with clinically suspected PE.

PATIENTS AND METHODS

We studied the VTE-failure rate of 2206 consecutive patients with an unlikely clinical probability in whom VIDAS or Tinaquant D-Dimer tests were performed.

RESULTS

The prevalence of PE in 1238 patients whose D-Dimer level was analyzed with Tinaquant assay was 11%. The VIDAS assay group consisted of 968 patients with a PE prevalence of 13%. The VIDAS assay had a sensitivity of 99.2% (95%CI; 96- >99.9%), the Tinaquant assay of 97.3% (95%CI; 93 -99%). The negative predictive value (NPV) in the Tinaquant assay group was 99.4% (95%CI 98-99.8%) in comparison to 99.7% (95%CI 99->99.9%) in the VIDAS assay group. During 3 month of follow-up, there were no fatal cases of PE among patients with normal D-Dimer and unlikely clinical probability in both D-Dimer assay groups. In addition, the test efficiency of Tinaquant assay was significantly higher in comparison to VIDAS assay (52% vs 42%, p<0.001).

CONCLUSION

Both Tinaquant and VIDAS D-Dimer tests perform equally well in combination with an unlikely clinical probability in excluding PE. The Tinaquant test was shown to be more efficient.

Direct comparison of the diagnostic accuracy of fifty protein biological markers of pulmonary embolism for use in the emergency department

OBJECTIVES

Pulmonary embolism (PE) is associated with abnormal concentrations of many proteins involved in inflammation, hemostasis, and vascular injury. The authors quantified the diagnostic accuracy of a battery of protein biological markers for the detection of PE in emergency department (ED) patients.

METHODS

A random and a consecutive sample of ED patients evaluated for PE were prospectively enrolled at two academic EDs between August 2005 and April 2006. A plasma sample was obtained at enrollment, and all patients were followed by telephone and medical record review at 90 days for the development of venous thromboembolism (VTE) defined as PE or deep venous thrombosis (DVT), requiring the consensus of two of three blinded physician reviewers. Measurements of potential biological markers were performed by technicians blinded to the study objectives. The diagnostic accuracy of each biological marker was determined by the area under the receiver operating characteristic (ROC) curve.

RESULTS

Fifty potential biological markers were measured in 304 ED patients, including 22 patients (7%, 95% confidence interval [CI] = 4% to 10%) with VTE. Fourteen biological markers demonstrated an area under the curve (AUC) with the lower limit of the 95% CI > or = 0.5. Of these, three demonstrated an AUC > or = 0.7: D-dimer (0.90), C-reactive protein (CRP; 0.78), and myeloperoxidase (MPO; 0.78).

CONCLUSIONS

From 50 candidate biological markers, only D-dimer, CRP, and MPO demonstrated sufficient diagnostic accuracy to suggest potential utility as biological marker of PE.

Diagnostic accuracy of the Triage® D-dimer test for exclusion of venous thromboembolism in outpatients

BACKGROUND

We evaluated the diagnostic performance of the Triage D-dimer test, a new fast quantitative point-of-care whole blood D-dimer assay and compared it with the Vidas D-dimer assay.

MATERIALS AND METHODS

The study population comprised 319 outpatients for whom D-dimer testing was requested in order to rule out venous thromboembolism (VTE). Routine testing consisted of a plasma ELISA D-dimer analysis (Vidas). For all included patients, an additional EDTA whole blood D-dimer test (Triage) was performed. Patients were classified by reference imaging or by follow-up of the medical record. Accuracy indices, receiver operating characteristics and the kappa coefficient for agreement were calculated using the cutoff values recommended by the manufacturer.

RESULTS

Prevalence of VTE was 14%. Sensitivity and specificity for VTE were 98% (95%CI: 88-100) and 34% (95%CI: 28-40) for Vidas and 91% (95%CI: 78-97) and 42% (95%CI: 36-48) for Triage, respectively. The differences in sensitivity and specificity between both D-dimer assays were statistically significant (McNemar, p<0.0001). ROC-curve analysis yielded an area under the curve of 0.83 (95%CI: 0.76-0.89) for the Vidas and 0.81 (95%CI: 0.74-0.88) for the Triage (p=0.396). The kappa coefficient for agreement between Vidas and Triage was 0.75 (95%CI: 0.68-0.79).

CONCLUSIONS

The Triage and Vidas D-dimer tests show comparable diagnostic accuracy. Vidas showed a significant higher sensitivity. Our findings strongly suggest lowering the cutoff for the Triage D-dimer test from 400 to 350 ng/mL. In this way specificity lowers from 42 to 38%, but, more importantly, sensitivity increases from 91 to 95%.

Radiologic diagnoses of patients who received imaging for venous thromboembolism despite negative D-dimer tests

OBJECTIVE

The literature supports a negative D-dimer (-DD) excluding venous thromboembolic disease (VTE) in low-risk patients. We determined the radiologic diagnoses in patients where imaging was ordered despite a -DD.

METHODS

This is a retrospective chart review of patients with a -DD (Tinaquant; Roche Diagnostics, Mannheim, Germany) and a radiologic study within 48 hours, sought to determine radiologic diagnosis (primary outcome), treatment of VTE, and consensus diagnosis of acute VTE.

RESULTS

Among 3462 DD tests, 1678 met the inclusion criteria. Of 1362 patients with DD values of 350 ng/mL or less, 166 (12.2%) had radiologic studies: 93.4% of the final radiologic diagnoses were negative for VTE, 3.6% were indeterminate, and 3.0% (1.0%-6.9%) were positive; 1.8% ultimately had a consensus diagnosis of acute VTE. In 316 patients with DD values between 351 and 500 ng/mL, 88 (27.8%) had radiologic studies: 95.5% were negative, 1.1% were indeterminate, and 3.4% (0.7%-9.6%) were positive.

CONCLUSIONS

Of patients who receive radiologic studies despite -DD tests, 3.0% have positive radiologic diagnoses for acute VTE; only 1.8% had acute VTE after the review of their hospital course.

Uses of different D-dimer levels can reduce the need for venous duplex scanning to rule out deep vein thrombosis in patients with symptomatic pulmonary embolism

OBJECTIVE

This study investigated the prevalence and distribution of deep vein thrombosis (DVT) in patients with symptomatic pulmonary embolism (PE) to establish a screening protocol to reduce unnecessary venous duplex scanning using different D-dimer level rather than single cutoff point of 0.5 microg/mL in patients with low and moderate pretest clinical probability (PTP).

METHODS

The PTP score and D-dimer testing were used to evaluate 85 consecutive patients with symptomatically proven PE before venous duplex scanning. After calculating the PTP score, patients were divided into low (<or=0 points), moderate (1 to 2 points), and high (>or=3 points) PTP groups. The receiver operating characteristic (ROC) curves analysis was used to determine the appropriate D-dimer cutoff point in low and moderate PTP, with a negative predictive value of >98%.

RESULTS

The study enrolled 81 patients. The prevalence of DVT was 63%, with 27 patients (33%) classified as low, 38 (47%) as moderate, and 16 (20%) as high PTP. DVT was detected in nine patients (33%) in the low PTP group, in 27 (71%) in the moderate group, and in 15 (94%) in the high group. In the low PTP patients, the difference in the value of D-dimer assay between positive-scan and negative-scan patients was statistically significant (9.99 +/- 7.33 vs 3.46 +/- 4.20, respectively; P = .008). Conversely, no significant difference in the D-dimer assay value between positive and negative scan results was found in the moderate PTP patients. ROC curves analysis were used to select D-dimer cutoff points of 2.0 microg/mL for the low PTP group and 0.7 microg/mL for the moderate PTP groups. For both groups, D-dimer testing provided 100% sensitivity and 100% negative predictive value in the diagnosis of DVT. In the low PTP group, specificity increased from 33% to 67% (P = .046). In the moderate PTP group, however, the determined D-dimer level did not improve the specificity. Overall, venous duplex scanning could have been reduced by 17% (14/81) by using different D-dimer cutoff points.

CONCLUSIONS

A combination of specific D-dimer level and clinical probability score is most effective in the low PTP patients in excluding DVT. In the moderate PTP group, however, the recommended cutoff point of 0.5 microg/mL may be preferable. These results show that a different D-dimer level is more useful than single cutoff point of 0.5 microg/mL in excluding DVT in established PE patients.

Influence of age on the cost-effectiveness of diagnostic strategies for suspected pulmonary embolism

BACKGROUND

Age has a marked effect on the diagnostic yield of D-dimer measurement and lower limb compression ultrasonography (CUS) in patients with suspected pulmonary embolism (PE), suggesting that specific diagnostic strategies may be needed in elderly patients.

OBJECTIVE

To evaluate the cost-effectiveness of including D-dimer and CUS in the workup of PE, with particular attention to patient age.

SUBJECTS AND METHODS

We analyzed data from two recent outcome studies that enrolled 1721 consecutive outpatients with suspected PE. Both studies used a sequential diagnostic strategy that included assessment of clinical probability, D-dimer measurement, CUS, and helical computed tomography (hCT). A decision analysis model was created for analyzing cost-effectiveness according to six classes of age. The main outcome measures were 3-month quality-adjusted expected survival and costs per patient managed.

RESULTS

All strategies were equally safe, with variations in the 3-month survival never exceeding 0.5% as compared to the most effective strategy. D-dimer measurement was highly cost-saving under the age of 80 years. Above 80 years, the cost-sparing effect of D-dimer was diminished, but not completely abolished. Inclusion of CUS increased the costs of diagnostic strategies irrespective of age. Results were unchanged over a wide range of the variables of interest (costs, sensitivity, and specificity of the tests).

CONCLUSIONS

Diagnostic strategies using D-dimer are less expensive. The cost-sparing effect of D-dimer is reduced but not abolished above 80 years, suggesting that adapting specific diagnostic strategies in elderly outpatients is not mandatory. CUS is costly, and only marginally improves the safety of diagnostic strategies for PE.

Risk tolerance for the exclusion of potentially life-threatening diseases in the ED

OBJECTIVE

Given the same pretest probability (10%) for subarachnoid hemorrhage (SAH), pulmonary embolism (PE), and acute coronary syndrome (ACS), we determined if differences exist in the risk tolerance for disease exclusion according to published guidelines given a negative test result.

METHODS

Published guidelines that make practice recommendations on the evaluation of ACS, PE, and SAH were sought using the National Guideline Clearinghouse in low-risk settings. Second-order Monte Carlo simulation was performed to determine point estimates and confidence intervals (CIs) for posttest probabilities assuming a pretest probability of 10%.

RESULTS

Guidelines recommend that patients with low-risk suspected ACS should undergo stress testing. For SAH, computed tomography (CT) followed by lumbar puncture (LP) is recommended without mention of pretest probability; and D-dimer testing is recommended to exclude PE in low-risk patients. Test sensitivity for thallium-201 single photon emission computed tomography (SPECT) was 89%, exercise echocardiogram was 85%, D-dimer testing was 95%, and CT/LP for SAH was 100% (as a gold standard) and CT only was 97.5%. Given a negative test result, for PE, posttest probability was 0.5% (95% CI 0.1%-0.9%); for SPECT, 1.1% (SD 0.5%-1.6%); and for exercise echocardiogram, 1.5% (95% CI 0.5%-2.5%) compared with a posttest probability of 0% for CT followed by LP for SAH. Using a CT-only approach gives a posttest probability of 0.2% (95% CI 0.2%-0.4%).

CONCLUSIONS

Guidelines for suspected PE and ACS allow small but nonzero calculated risk end points in low-risk settings, whereas SAH guidelines afford no misses. Because many gold standard tests are more invasive and can have adverse effects, guideline authors should consider adopting a standard acceptable miss rate as an end point for workups with low clinical suspicion to avoid the overuse of invasive testing.

Pulmonary embolism risk assessment screening tools: the interrater reliability of their criteria

BACKGROUND

Diagnostic evaluation for suspected pulmonary embolism (PE) is challenging. Dimerized plasmin fragment D (D-dimer) assays are increasingly used but have been validated only in "low-risk" patients. The accurate interpretation and application of risk assessment criteria are critical to the appropriate use of D-dimer. We sought to determine the interrater agreement of attending and third-year resident emergency medicine physicians in the specific elements of the Canadian and the Charlotte risk stratification tools and their clinical application.

METHODS

We prospectively enrolled a convenience sample of patients presenting to an urban university emergency department with suspected PE. Standardized data collection sheets were used by an attending physician and a third-year resident physician to determine the presence or absence of risk factors included in published PE prediction instruments. Each physician was blinded to the other's results and the patients' D-dimer result. Interrater agreement was measured using kappa statistics (with 95% confidence intervals).

RESULTS

Two hundred seventy-one patients were screened. The kappa scores for each risk criterion were as follows: previous deep vein thrombosis, 0.90 (95% confidence interval, 0.83-0.97); malignancy, 0.87 (0.76-0.97); deep vein thrombosis symptoms, 0.54 (0.39-0.70); immobilization, 0.41 (0.26-0.57); unexplained hypoxia, 0.58 (0.42-0.74); tachycardia, 0.94 (0.89-0.98); hemoptysis, 0.76 (0.51-1.0); and PE more likely than another diagnosis, 0.50 (0.36-0.64).

CONCLUSIONS

Interrater agreement was only fair for several important risk criteria. Small differences in determining pretest probability can lead to significant variability in risk assessment and how, or whether, the diagnosis of PE is evaluated. This study raises questions about the reliability and applicability of published PE screening criteria in clinical settings.