Negative D-dimer Test Research Articles

D-dimer test for excluding the diagnosis of pulmonary embolism.

Pulmonary embolism (PE) can occur when a thrombus (blood clot) travels through the veins and lodges in the arteries of the lungs, producing an obstruction. People who are thought to be at risk include those with cancer, people who have had a recent surgical procedure or have experienced long periods of immobilisation and women who are pregnant. The clinical presentation can vary, but unexplained respiratory symptoms such as difficulty breathing, chest pain and an increased respiratory rate are common.D-dimers are fragments of protein released into the circulation when a blood clot breaks down as a result of normal body processes or with use of prescribed fibrinolytic medication. The D-dimer test is a laboratory assay currently used to rule out the presence of high D-dimer plasma levels and, by association, venous thromboembolism (VTE). D-dimer tests are rapid, simple and inexpensive and can prevent the high costs associated with expensive diagnostic tests. To investigate the ability of the D-dimer test to rule out a diagnosis of acute PE in patients treated in hospital outpatient and accident and emergency (A&E) settings who have had a pre-test probability (PTP) of PE determined according to a clinical prediction rule (CPR), by estimating the accuracy of the test according to estimates of sensitivity and specificity. The review focuses on those patients who are not already established on anticoagulation at the time of study recruitment. We searched 13 databases from conception until December 2013. We cross-checked the reference lists of relevant studies. Two review authors independently applied exclusion criteria to full papers and resolved disagreements by discussion.We included cross-sectional studies of D-dimer in which ventilation/perfusion (V/Q) scintigraphy, computerised tomography pulmonary angiography (CTPA), selective pulmonary angiography and magnetic resonance pulmonary angiography (MRPA) were used as the reference standard.• Adults who were managed in hospital outpatient and A&E settings and were suspected of acute PE were eligible for inclusion in the review if they had received a pre-test probability score based on a CPR.• quantitative, semi quantitative and qualitative D-dimer tests.• Target condition: acute symptomatic PE.• Reference standards: We included studies that used pulmonary angiography, V/Q scintigraphy, CTPA and MRPA as reference standard tests. Two review authors independently extracted data and assessed quality using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). We resolved disagreements by discussion. Review authors extracted patient-level data when available to populate 2 × 2 contingency tables (true-positives (TPs), true-negatives (TNs), false-positives (FPs) and false-negatives (FNs)). We included four studies in the review (n = 1585 patients). None of the studies were at high risk of bias in any of the QUADAS-2 domains, but some uncertainty surrounded the validity of studies in some domains for which the risk of bias was uncertain. D-dimer assays demonstrated high sensitivity in all four studies, but with high levels of false-positive results, especially among those over the age of 65 years. Estimates of sensitivity ranged from 80% to 100%, and estimates of specificity from 23% to 63%. A negative D-dimer test is valuable in ruling out PE in patients who present to the A&E setting with a low PTP. Evidence from one study suggests that this test may have less utility in older populations, but no empirical evidence was available to support an increase in the diagnostic threshold of interpretation of D-dimer results for those over the age of 65 years.

Multi-faceted implementation strategy to increase use of a clinical guideline for the diagnosis of deep venous thrombosis in primary care.

A clinical decision rule (CDR), combined with a negative D-dimer test, can safely rule out deep venous thrombosis (DVT) in primary care. This strategy is recommended by guidelines, yet uptake by GPs is low. To evaluate a multi-faceted implementation strategy aimed at increased use of the guideline recommended CDR plus D-dimer test in primary care patients with suspected DVT. This multi-faceted implementation strategy consisted of educational outreach visits, financial reimbursements and periodical newsletters. 217 Dutch GPs (implementation group) received this strategy and included patients. Effectiveness was measured through the following patient-level outcomes: (i) proportion of non-referred patients, (ii) proportion of missed DVT cases within this group and (iii) the proportion of patients in whom the guideline was applied incorrectly. Implementation outcomes ('acceptability', 'feasibility', 'fidelity' and 'sustainability') were assessed with an online questionnaire. Patient-level outcomes were compared with those of patients included by 450 GPs, uninformed about the study's purposes providing information about usual care. 336 (54%) of 619 analyzable implementation group patients were not referred, missing 6 [1.8% (95% confidence interval 0.7% to 3.9%)] DVT cases. Incorrect guideline use was observed in 199 patients (32%). Self-reported acceptability, feasibility and expected sustainability were high. Guideline use increased from 42% to an expected continuation of use of 91%. Only 32 usual care GPs included 62 patients, making formal comparison unreliable. This multi-faceted implementation strategy safely reduced patient referral to secondary care, despite frequently incorrect application of the guideline and resulted in high acceptability, feasibility and expected sustainability.

D-dimer levels and recurrence in patients with unprovoked VTE and a negative qualitative D-dimer test after treatment

BackgroundThe rate of recurrent venous thromboembolism (VTE) in patients with a first unprovoked VTE who had a negative qualitative D-dimer test one month after stopping anticoagulant therapy was higher than expected in the D-dimer Optimal Duration Study (DODS). ObjectivesTo determine whether quantitative D-dimer levels using a low threshold, age- and sex-specific thresholds, or repeated measurements, would improve identification of patients at low risk of recurrent VTE. Materials and methodsD-dimer levels were quantified in banked samples from 307 patients in DODS who had a negative qualitative D-dimer test while on, and 1month after stopping, anticoagulant therapy and the rates of recurrent VTE were determined in patients with D-dimer levels below various predefined thresholds. ResultsThe rate (per patient year) of recurrent VTE was: 5.9% with D-dimer levels<250μg/l at one month; 5.2% with D-dimer levels between 250 and 499μg/l at one month; 5.0% with D-dimer levels less than predefined age- and sex-specific thresholds at one month; and 6.3% when D-dimer levels were <500μg/l at both one and 7months after stopping anticoagulant therapy. These rates are similar to the overall event rate of 6.3% in patients who stopped treatment. ConclusionsAmong unprovoked VTE patients who had a negative qualitative D-dimer test during and after anticoagulant therapy, low D-dimer thresholds, age and sex-adjusted thresholds or repeated measurements, did not identify subgroups with a very low rate of recurrence.

Diagnosis of pregnancy-associated venous thromboembolism - position paper of the Working Group in Women's Health of the Society of Thrombosis and Haemostasis (GTH).

Pregnancy and the postpartum period are associated with an increased risk of venous thromboembolism (VTE). Over the past decade, new diagnostic algorithms have been established, combining clinical probability, laboratory testing and imaging studies for the diagnosis of deep vein thrombosis (DVT) and pulmonary embolism (PE) in the non-pregnant population. However, there is no such generally accepted algorithm for the diagnosis of pregnancy-associated VTE. Studies establishing clinical prediction rules have excluded pregnant women, and prediction scores currently in use have not been prospectively validated in pregnancy or during the postpartum period. D-dimers physiologically increase throughout pregnancy and peak at delivery, so a negative D-dimer test result, based on the reference values of non-pregnant subjects, becomes unlikely in the second and third trimesters. Imaging studies therefore play a major role in confirming suspected DVT or PE in pregnant women. Major concerns have been raised against radiologic imaging because of foetal radiation exposure, and doubts about the diagnostic value of ultrasound techniques in attempting to exclude isolated iliac vein thrombosis grow stronger as pregnancy progresses. As members of the Working Group in Women's Health of the Society of Thrombosis and Haemostasis (GTH), we summarise evidence from the available literature and aim to establish a more uniform strategy for diagnosing pregnancy-associated VTE.

Rapid quantitative D‐dimer to exclude pulmonary embolism: a prospective cohort management study

ESSENTIALS: It is not known if D-dimer testing alone can safely exclude pulmonary embolism (PE). We studied the safety of using a quantitative latex agglutination D-dimer to exclude PE in 808 patients. 52% of patients with suspected PE had a negative D-dimer test and were followed for 3 months. The negative predictive value of D-dimer testing alone was 99.8%, suggesting it may safely exclude PE. Strategies are needed to exclude pulmonary embolism (PE) efficiently without the need for imaging tests. Although validated rules for clinical probability assessment can be combined with D-dimer testing to safely exclude PE, the rules can be complicated or partially subjective, which limits their use. To determine if PE can be safely excluded in patients with a negative D-dimer without incorporating clinical probability assessment. We enrolled consecutive outpatients and inpatients with suspected PE from four tertiary care hospitals. All patients underwent D-dimer testing using the MDA D-dimer test, a quantitative latex agglutination assay. PE was excluded in patients with a D-dimer less than 750 μg FEU L(-1) without further testing. with D-dimer levels of 750 μg FEU L(-1) or higher underwent standardized imaging tests for PE. All patients in whom PE was excluded had anticoagulant therapy withheld and were followed for 3 months for venous thromboembolism (VTE). Suspected events during follow-up were adjudicated centrally. Eight hundred and eight patients were enrolled, of whom 99 (12%) were diagnosed with VTE at presentation. Four hundred and twenty (52%) patients had a negative D-dimer level at presentation and were not treated with anticoagulants; of these, one had VTE during follow-up. The negative predictive value of D-dimer testing for PE was 99.8% (95% confidence interval, 98.7-99.9%). A negative latex agglutination D-dimer assay is seen in about one-half of patients with suspected PE and reliably excludes PE as a stand-alone test.

Reliability of D-Dimer test results in deciding the necessity of performing CTA in high risk population to establish the diagnosis of PE

PurposeTo evaluate the reliability of D-Dimer test results in the diagnosis of PE in high risk patients. Patients and methodsThis prospective study was conducted on 98 patients. Mean age was 50years; age range was 17–88years. All patients underwent D-Dimer assay. Multidetector CT Angiography (MDCTA) was performed on 128 row multi-slice scanner. Statistical analysis of D-Dimer test values was attempted to assess its diagnostic reliability. Patients were further stratified into two groups: patients with positive D-Dimer test and patients with negative D-Dimer test, and cut-off value patients with negative D-Dimer test and cutoff value was estimated for D-Dimer test results. ResultsStatistical analysis of D-Dimer test values yielded sensitivity 100%, specificity 28% with 100% negative predictive value (NPP) and low positive predictive value (26%). Likelihood ratios were NLR <0.1 and PLR <1. Cutoff value for D-Dimer test results in correlation with CT Angiography results, was 1.45μg/ml, with diagnostic sensitivity 87% and diagnostic specificity 57%. PLR was 0.43 and NLR was 0.13. ConclusionNegative D-Dimer test is a reliable diagnostic modality to rule out the need for CT Angiography in patients at high risk population of PE. However, positive test results cannot confirm the diagnosis and further testing is warranted.

Stopping Anticoagulant Therapy in Patients with First Unprovoked Venous Thromboembolism

Do all patients with first unprovoked venous thromboembolism (VTE) require long-term anticoagulation? In this study, researchers evaluated whether a negative d-dimer test result safely identifies patients in whom anticoagulation can be stopped. d-dimer testing was done in 410 patients with first episodes of unprovoked VTE (i.e., proximal deep venous thrombosis of the legs or pulmonary embolism) who had been receiving anticoagulation therapy for 3 to …

Assessment of the Safety and Efficiency of Using an Age-Adjusted D-dimer Threshold to Exclude Suspected Pulmonary Embolism

BACKGROUND:D-dimer levels increase with age, and research has suggested that using an age-adjusted D-dimer threshold may improve diagnostic efficiency without compromising safety. The objective of this study was to assess the safety of using an age-adjusted D-dimer threshold in the workup of patients with suspected pulmonary embolism (PE).METHODS:We report the outcomes of 923 patients aged > 50 years presenting to our ED with suspected PE, a calculated Revised Geneva Score (RGS), and a D-dimer test. All patients underwent CT pulmonary angiography (CTPA). We compared the false-negative rate for PE of a conventional D-dimer threshold with an age-adjusted D-dimer threshold and report the proportion of patients for whom an age-adjusted D-dimer threshold would obviate the need for CTPA.RESULTS:Among 104 patients with a negative conventional D-dimer test result and an RGS ≤ 10, no PE was observed within 90 days (false-negative rate, 0%; 95% CI, 0%-2.8%). Among 273 patients with a negative age-adjusted D-dimer result and an RGS ≤ 10, four PEs were observed within 90 days (false-negative rate, 1.5%; 95% CI, 0.4%-3.7%). We observed an 18.3% (95% CI, 15.9%-21.0%) absolute reduction in the proportion of patients aged > 50 years who would merit CTPA by using an age-adjusted D-dimer threshold compared with a conventional D-dimer threshold.CONCLUSIONS:Use of an age-adjusted D-dimer threshold reduces imaging among patients aged > 50 years with an RGS ≤ 10. Although the adoption of an age-adjusted D-dimer threshold is probably safe, the CIs surrounding the additional 1.5% of PEs missed necessitate prospective study before this practice can be adopted into routine clinical care.

Alternative diagnoses in patients in whom the GP considered the diagnosis of pulmonary embolism.

Pulmonary embolism (PE) often presents with nonspecific symptoms and may be an easily missed diagnosis. When the differential diagnosis includes PE, an empirical list of frequently occurring alternative diagnoses could support the GP in diagnostic decision making. To identify common alternative diagnoses in patients in whom the GP suspected PE but in whom PE could be ruled out. To investigate how the Wells clinical decision rule for PE combined with a point-of-care d-dimer test is associated with these alternative diagnoses. Secondary analysis of the Amsterdam Maastricht Utrecht Study on thrombo-Embolism (Amuse-2) study, which validated the Wells PE rule combined with point-of-care d-dimer testing in primary care. All 598 patients had been referred to and diagnosed in secondary care. All diagnostic information was retrieved from the GPs' medical records. In 516 patients without PE, the most frequent alternative diagnoses were nonspecific thoracic pain/dyspnoea (42.6%), pneumonia (13.0%), myalgia (11.8%), asthma/chronic obstructive pulmonary disease (4.8%), panic disorder/hyperventilation (4.1%) and respiratory tract infection (2.3%). Pneumonia occurred almost as frequent as PE. Patients without PE with either a positive Wells rule (>4) or a positive d-dimer test, were more often (odds ratio = 2.1) diagnosed with a clinically relevant disease than patients with a negative Wells rule and negative d-dimer test. In primary care patients suspected of PE, the most common clinically relevant diagnosis other than PE was pneumonia. A positive Wells rule or a positive d-dimer test are not only positively associated with PE, but also with a high probability of other clinically relevant disease.

Exclusion of deep vein thrombosis using the Wells rule in clinically important subgroups: individual patient data meta-analysis

Objective To assess the accuracy of the Wells rule for excluding deep vein thrombosis and whether this accuracy applies to different subgroups of patients.Design Meta-analysis of individual patient data. Data...

How can we improve the diagnosis of deep vein thrombosis and pulmonary embolism at the primary level?

c i n e ltd Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is not uncommon in primary care, with a reported incidence of almost one case per 1000 person-years [1]. VTE is highly feared for its associated mortality, since the risk of PE-related early mortality may be higher than 15%, as well as its associated morbidity, since patients with VTE may also develop long-term complications such as chronic thromboembolic pulmonary hypertension or postphlebitic syndrome [2]. On the other hand, anticoagulation is an effective treatment for VTE, but carries a non-negligible rate of major bleeding events, ranging from 2% in clinical trials to 7.4% in population cohort studies [3]. When VTE is suspected, it is therefore mandatory to quickly achieve the correct diagnosis. Nonetheless, this process is particularly difficult in primary care, because of the limited number of available diagnostic tools and the nonspecific clinical presentations of DVT and PE. Therefore, the ultimate aim is to determine in which patients DVT or PE can be safely ruled out and which patients should be referred for additional diagnostic workup in secondary care. The current diagnostic approach to VTE is based on the combination of three tools: diagnostic clinical prediction rules (CPRs) for assessing the pretest probability; d-dimer measurement; and imaging tests (i.e., venous ultrasono graphy for DVT and computed tomo graphy pulmonary angiography [CTPA] or ventilation-perfusion lung scan for PE). In patients who present with suspected DVT, the CPR developed by Wells and colleagues is currently the most used worldwide [4]. The Wells CPR includes information from patients’ medical history (active cancer, recent immobilization of the lower extremities, recent bedridden or major surgery), physical examination (tenderness along the deep venous system, entire leg swollen or calf difference greater than 3 cm, pitting edema and collateral superficial veins) and a subjective variable (i.e., an alternative diagnosis for patients’ symptoms) [4]. As the Wells CPR has been developed for secondary care outpatients, its applicability to primary care is still uncertain. A prospective validation study showed that the Wells CPR, in combination with a negative quantitative d-dimer test, did not adequately rule out DVT in the primary care setting [5]. This result could be partly due to different population characteristics, since secondary care patients are often selected by primary care physicians, and partly to the subjectively estimated probability of an alternative diagnosis, which might be assessed differently by general practitioners and by specialists. Oudega and colleagues have developed a specific primary care CPR for suspected DVT that included eight simple diagnostic indicators (male gender, oral contraceptive use, presence of malignancy, recent surgery, absence of leg trauma, vein Nicoletta Riva Research Center on Thromboembolic Disorders & Antithrombotic Therapies, Department of Clinical & Experimental Medicine, University of Insubria, Varese, Italy

Diagnostic accuracy of D-dimer assay in suspected pulmonary embolism patients

BackgroundPulmonary embolism (PE) is a frequent and potentially severe disease. So objective testing is required to establish or exclude the presence of pulmonary embolism. AimThis study was carried out to evaluate the diagnostic accuracy of D-dimer test in suspected pulmonary embolism patients. Patients and MethodsThis study was carried out on 30 patients with clinical and radiological signs suspicious of PE. All cases were subjected to the following: evaluation of clinical probability by Revised Geneva Score, plain chest X-ray, CT pulmonary angiography (CTPA), electrocardiographic examination, arterial blood gases analysis, calculated alveolar arterial oxygen (PA-aO2) gradient, duplex ultrasonographic, D-dimer assay, and measurement of partial end tidal carbon dioxide (PetCO2). ResultsPE confirmed in 22 cases by CTPA, 20 cases of PE (91%) had positive D-dimer and 2 cases (9%) had negative D-dimer test. The sensitivity, specificity and accuracy of D-dimer in diagnosis of PE were (90%, 37.5%, and 26.6%) respectively. The sensitivity of D-dimer in evaluation of PE when clinical probability of PE low or intermediate was (100%), its specificity was (37.5%), its negative predictive value (NPV) was (100%) and its positive predictive value (PPV) was (67.7%), while in high clinical probability its sensitivity was (83.3%), specificity was (100%) and its PPV was (100%). There was statistically significant difference among the negative and positive PE cases as regards the PetCO2 result (P<0.05). The sensitivity of PetCO2 in diagnosis of PE was (68%) its specificity was (87.5%), NPV was (50%) and its PPV was (93.7%). ConclusionD-dimer alone cannot exclude or confirm the presence of PE. The combination of D-dimer, PetCO2 ⩽28.5mmHg and the clinical probability could improve diagnostic accuracy in patients with suspected PE.

Evaluation of the Alere D-dimer test for point of care testing

The primary care regularly sees patients that have symptoms that could be due to thromboembolic diseases. It would be valuable to be able to rule out deep venous thrombosis or pulmonary embolism using Wells score and a negative D-dimer testing already at the primary care unit. This requires a validated D-dimer assay suitable for primary care use. We compared D-dimer results obtained with the new point of care analyzer Alere Triage(®) and the central hospital laboratory STA-R Evolution analyzer from the same patient samples (n = 102). We also calculated the total coefficient of variation (CV) for the Alere method. The two methods showed a good linear correlation (R(2) = 0.977) and a slope of 0.975. CV for the Alere D-dimer method was well below 10%. The study shows that the Alere D-dimer assay and the central laboratory standard assay show similar results. We suggest that the Alere D-dimer assay could be used in primary care in combination with Wells score to reduce referrals to the emergency unit.

The additional value of the CRP test in patients in whom the primary care physician excluded pulmonary embolism

Background: After excluding pulmonary embolism (PE) with an unlikely Wells-decision rule and a negative D-dimer test, the general practitioner still has to differentiate between clinically relevant and clinically non-relevant diseases accounting for the presented symptoms. A negative D-dimer test makes clinically relevant disease less likely. The C-reactive protein (CRP) test could be of additional value to make this differentiation.Objectives: To assess whether an unlikely Wells-decision rule in combination with a negative point of care D-dimer test not only can safely exclude PE but also, in combination with a negative CRP-test, any other clinically relevant disease.Methods: We used data of a prospective study including 598 primary care patients suspected of pulmonary embolism. We included all patients, referred to secondary care for reference testing, with an unlikely Wells-decision rule and a negative point of care D-dimer test. We included 191 patients and imputed the CRP-test results in 60 patients. Alternative diagnoses were divided in clinically relevant diseases and clinically non-relevant diseases. A ROC-curve was constructed to determine the optimal CRP-cut-off.Results: The optimal CRP cut-off value appeared to be 10 mg/l. A total of 116 patients had a CRP < 10 mg/l of whom 12 patients (10%) had a clinically relevant disease. Two patients (2%) needed hospital admission. A total of 75 patients had a CRP ≥ 10 mg/l of whom 32 patients (43%) had a clinically relevant disease. Fifteen patients (20%) were admitted to hospital.Conclusion: The CRP-test is enhancing diagnostic decision making in patients in whom the general practitioner excluded PE.

Expedited Management of Deep Vein Thrombosis and Acute Pulmonary Embolism

Deep vein thrombosis and pulmonary embolism are common diseases with significant morbidity and mortality. Clinical probability assessment reliably identifies low-risk patients, and when paired with a negative D-dimer test, safely excludes venous thromboembolism. Compression ultrasonography confirms the diagnosis of deep vein thrombosis, whereas computed tomography pulmonary angiography is typically used to confirm pulmonary embolism. Risk assessment of acute pulmonary embolism stratifies low-risk patients for outpatient treatment, and high-risk patients for consideration of thrombolytic therapy. The recent approval of rivaroxaban, a novel oral anticoagulant, can simplify and expedite treatment in select patients. Ongoing clinical trials may uncover methods to prevent postthrombotic syndrome and chronic thromboembolic pulmonary hypertension. In this report, we review current diagnostic and management methods for deep vein thrombosis and pulmonary embolism.

Adherence to PIOPED II Investigators' Recommendations for Computed Tomography Pulmonary Angiography

BackgroundComputed tomography (CT) pulmonary angiography use has increased dramatically, raising concerns for patient safety. Adherence to recommendations and guidelines may protect patients. We measured adherence to the recommendations of Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED II) investigators for evaluation of suspected pulmonary embolism and the rate of potential false-positive pulmonary embolism diagnoses when recommendations of PIOPED II investigators were not followed. MethodsWe used a structured record review to identify 3500 consecutive CT pulmonary angiograms performed to investigate suspected pulmonary embolism in 2 urban emergency departments, calculating the revised Geneva score (RGS) to classify patients as “pulmonary embolism unlikely” (RGS≤10) or “pulmonary embolism likely” (RGS>10). CT pulmonary angiograms were concordant with PIOPED II investigator recommendations if pulmonary embolism was likely or pulmonary embolism was unlikely and a highly sensitive D-dimer test result was positive. We independently reviewed 482 CT pulmonary angiograms to measure the rate of potential false-positive pulmonary embolism diagnoses. ResultsA total of 1592 of 3500 CT pulmonary angiograms (45.5%) followed the recommendations of PIOPED II investigators. The remaining 1908 CT pulmonary angiograms were performed on patients with an RGS≤10 without a D-dimer test (n=1588) or after a negative D-dimer test result (n=320). The overall rate of pulmonary embolism was 9.7%. Potential false-positive diagnoses of pulmonary embolism occurred in 2 of 3 patients with an RGS≤10 and a negative D-dimer test result. ConclusionsNonadherence to recommendations for CT pulmonary angiography is common and exposes patients to increased risks, including potential false-positive diagnoses of pulmonary embolism.

Accuracy of Magnetic Resonance Direct Thrombus Imaging (MRDTI) As a Novel Tool in the Diagnosis of Acute Ipsilateral Recurrent Deep Vein Thrombosis

AbstractAbstract 395 BackgroundAccurate diagnostic assessment of suspected acute ipsilateral recurrent deep vein thrombosis (DVT) is of high clinical importance, however discriminating residual thrombosis from acute recurrent DVT may be challenging. It is known that in 32% of the patients with a suspected acute ipsilateral recurrent DVT the ultrasound examination are non-conclusive. Despite this, patients were treated with indefinite anticoagulant therapy, indicating overtreatment in this group of patients (Tan M et al. J Thromb Haemost 2010). A non-invasive MR technique (Magnetic Resonance Direct Thrombus Imaging (MRDTI), without need for intravenous contrast agent, showed high sensitivity and specificity for diagnosing a first acute DVT (Fraser et al Ann Intern Med 2002). Furthermore the high signal associated with acute thrombosis was not detected 6 months after the initial acute thrombosis, making MRDTI potential relevant for distinguishing a recurrent DVT from a residual thrombosis (Westerbeek RE et al J Thromb Haemost 2008). This study evaluated the accuracy of MRDTI in patients with an acute ipsilateral recurrent DVT and patients with residual thrombosis. Patients/MethodsIn total 84 patients were enrolled. Of these, 42 consecutive patients had an acute ipsilateral recurrent DVT according to the current ultrasound examination standards in combination with a positive D-dimer test (≥ 500 μg/L); all patients were treated with anticoagulants. Furthermore, 42 patients were without acute signs and symptoms, however had a residual thrombosis on ultrasound examination in combination with a negative D-dimer test (< 500 μg/L). All patients received a MR examination within 48 hours of presentation. MR images were assessed in a blinded fashion by two radiologists. Sensitivity, specificity and interobserver variability were calculated. ResultsThe images of two patients with ipsilateral recurrent DVT were not interpretable, one patient had a knee prosthesis that gave artifacts and in the other patient not the venous system of interest was imaged. The images of 40 patients with an ipsilateral recurrent DVT and of 42 patients with residual thrombosis were fully interpretable. Sensitivity was 86% (95% CI, 71 –94%) and specificity was 100% (95% CI, 89–100%) for MRDTI by the first observer; sensitivity was 88% (95% CI, 74–96%) and specificity was 100% (89–100%) by the second observer. The interobserver agreement between both observers was excellent, with a kappa statistics of 0.97 (95% CI, 0.92 – 1.0). ConclusionOur study shows reasonable sensitivity and very good specificity figures with an excellent observer agreement for imaging an ipsilateral recurrent DVT and residual thrombosis with MRDTI. The sensitivity is somewhat lower than expected; a reason could be that patients with inconclusive ultrasounds were considered as acute recurrent thrombosis by the attending physician, while in fact they had a residual thrombosis. We conclude that MRDTI has good potential in distinguishing a residual thrombosis from an acute recurrent DVT and could therefore be of high value for the diagnosis of patients with suspected acute ipsilateral recurrent DVT. This should however be further evaluated in a management outcome study in which treatment decisions are based on the results of MR. AcknowledgmentThis study was supported by the Netherlands Heart Foundation (grant no. 2007B146) Disclosures:No relevant conflicts of interest to declare.

Safe exclusion of pulmonary embolism using the Wells rule and qualitative D-dimer testing in primary care: prospective cohort study

Objective To validate the use of the Wells clinical decision rule combined with a point of care D-dimer test to safely exclude pulmonary embolism in primary care.Design Prospective cohort study.Setting...

Evaluation of Pulmonary Embolism in the Emergency Department and Consistency With a National Quality Measure

The National Quality Forum (NQF) has endorsed a performance measure designed to increase imaging efficiency for the evaluation of pulmonary embolism (PE) in the emergency department (ED). To our knowledge, no published data have examined the effect of patient-level predictors on performance. To quantify the prevalence of avoidable imaging in ED patients with suspected PE, we performed a prospective, multicenter observational study of ED patients evaluated for PE from 2004 through 2007 at 11 US EDs. Adult patients tested for PE were enrolled, with data collected in a standardized instrument. The primary outcome was the proportion of imaging that was potentially avoidable according to the NQF measure. Avoidable imaging was defined as imaging in a patient with low pretest probability for PE, who either did not have a D-dimer test ordered or who had a negative D-dimer test result. We performed subanalyses testing alternative pretest probability cutoffs and imaging definitions on measure performance as well as a secondary analysis to identify factors associated with inappropriate imaging. χ(2) Test was used for bivariate analysis of categorical variables and multivariable logistic regression for the secondary analysis. We enrolled 5940 patients, of whom 4113 (69%) had low pretest probability of PE. Imaging was performed in 2238 low-risk patients (38%), of whom 811 had no D-dimer testing, and 394 had negative D-dimer test results. Imaging was avoidable, according to the NQF measure, in 1205 patients (32%; 95% CI, 31%-34%). Avoidable imaging owing to not ordering a D-dimer test was associated with age (odds ratio [OR], 1.15 per decade; 95% CI, 1.10-1.21). Avoidable imaging owing to imaging after a negative D-dimer test result was associated with inactive malignant disease (OR, 1.66; 95% CI, 1.11-2.49). One-third of imaging performed for suspected PE may be categorized as avoidable. Improving adherence to established diagnostic protocols is likely to result in significantly fewer patients receiving unnecessary irradiation and substantial savings.

ACR Appropriateness Criteria® Acute Chest Pain—Suspected Pulmonary Embolism

Pulmonary embolism (PE) remains a common and important clinical condition that cannot be accurately diagnosed on the basis of signs, symptoms, and history alone. In the absence of high pretest probability and with a negative high-sensitivity D-dimer test, PE can be effectively excluded; in other situations, diagnostic imaging is necessary. The diagnosis of PE has been facilitated by technical advancements and multidetector computed tomography pulmonary angiography, which is the major diagnostic modality currently used. Ventilation and perfusion (V/Q) scans remain largely accurate and useful in certain settings. Lower-extremity ultrasound can substitute by demonstrating deep vein thrombosis; however, if negative, further studies to exclude PE are indicated. In all cases, correlation with the clinical status, particularly with risk factors, improves not only the accuracy of diagnostic imaging but also overall utilization. Other diagnostic tests have limited roles. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The development and review of the guidelines include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.