Conventional D-dimer Research Articles

An optimized D-dimer cut-off value to predict pulmonary thromboembolism in COVID-19 patients.

Pulmonary thromboembolism (PTE) is a common complication in coronavirus disease 2019 (COVID-19) patients. Elevated D-dimer levels are observed even in the absence of PTE, reducing its discriminative ability as a screening test. It is unknown whether conventional D-dimer cut-off values, as used in the YEARS algorithm, apply to COVID-19 patients. This study aimed to determine the optimal D-dimer cut-off value to predict PTE in COVID-19 patients. All confirmed COVID-19 patients with a computed tomography pulmonary angiography (CTPA) performed ≤5 days after admission due to suspicion of PTE between March 2020 and February 2021, at Medisch Spectrum Twente, The Netherlands, were retrospectively analyzed. The association between PTE and D-dimer levels prior to CTPA, and other potential predictors, was analyzed using logistic regression analyses. The optimal cut-off value was identified using receiver operating characteristic (ROC) curve analyses. In 142 patients, PTE prevalence was 20.4%. The optimal cut-off value was 750 ng/mL (sensitivity 100%; specificity 19.5%; negative predictive value 100%; positive predictive value 24.2%). In total, 15 of 113 (13%) patients without PTE had a D-dimer level ≥500 and <750 ng/mL. In our population of patients hospitalized with COVID-19, a D-dimer level <750 ng/mL safely excluded PTE. Compared to the YEARS 500 ng/mL cut-off value, 13% fewer patients are in need of a CTPA, with similar sensitivity. Future research is required for external validation.

Obesity as a Predictor for Pulmonary Embolism and Performance of the Age-Adjusted D-Dimer Strategy in Obese Patients with Suspected Pulmonary Embolism.

Obesity is a risk factor for venous thromboembolism, but studies evaluating its association with pulmonary embolism (PE) in patients with suspected PE are lacking. To evaluate whether body mass index (BMI) and obesity (i.e., BMI ≥30 kg/m2) are associated with confirmed PE in patients with suspected PE and to assess the efficiency and safety of the age-adjusted D-dimer strategy in obese patients. We conducted a secondary analysis of a multinational, prospective study, in which patients with suspected PE were managed according to the age-adjusted D-dimer strategy and followed for 3 months. Outcomes were objectively confirmed PE at initial presentation, and efficiency and failure rate of the diagnostic strategy. Associations between BMI and obesity, and PE were examined using a log-binomial model that was adjusted for clinical probability and hypoxia. We included 1,593 patients (median age: 59 years; 56% women; 22% obese). BMI and obesity were not associated with confirmed PE. The use of the age-adjusted instead of the conventional D-dimer cut-off increased the proportion of obese patients in whom PE was considered ruled out without imaging from 28 to 38%. The 3-month failure rate in obese patients who were left untreated based on a negative age-adjusted D-dimer cut-off test was 0.0% (95% confidence interval: 0.0-2.9%). BMI on a continuous linear scale and obesity were not predictors of confirmed PE among patients presenting with a clinical suspicion of PE. The age-adjusted D-dimer strategy appeared safe in ruling out PE in obese patients with suspected PE.

COVID-19-related dynamic coagulation disturbances and anticoagulation strategies using conventional D-dimer and point-of-care Sonoclot tests: a prospective cohort study

ObjectivesCoagulation changes associated with COVID-19 suggest the presence of a hypercoagulable state with pulmonary microthrombosis and thromboembolic complications. We assessed the dynamic association of COVID-19-related coagulation abnormalities with respiratory failure...

Age-Adjusted D-Dimer in Ruling Out Acute Aortic Syndrome.

Background Recently, D-dimer has been suggested as a biomarker to rule out acute aortic syndrome (AAS). Since it increases with age, this study was conducted to reveal whether an age-adjusted D-dimer can increase diagnostic accuracy in ruling out AAS. Method A retrospective observational study design was used. Consecutive adult patients who visited an emergency room between January 2015 and September 2020 and who underwent a D-dimer test and computed tomography angiography for suspected AAS were enrolled. We calculated the diagnostic accuracy of both the conventional (0.5 μg/ml) and age-adjusted (age × 0.01 in patients >50 years) D-dimer cut-offs. Result D-dimer was higher in the AAS group (n = 82) than in the non-AAS group (n = 122) (10.85 (3.61–33.12) vs. 0.40 (0.23–1.07), OR: 1.139 (CI: 1.085 – 1.195), p < 0.001). The D-dimer plasma level had an area under the ROC curve of 0.915 (CI: 0.873–0.956) with AAS. At the age-adjusted cutoff point compared to a 0.5 μg/ml cutoff, the sensitivity of 97.6% and the NLR of 0.04 did not change, but the specificity increased by 5.7% to 65.6%, the PPV increased by 3.6% to 65.6%, and the NPV slightly increased by 0.2% to 97.6%. Conclusion Compared with a conventional method, the age-adjusted D-dimer cutoff may have higher specificity and PPV while maintaining high sensitivity for ruling out AAS.

Performance of age-adjusted D-dimer values for predicting DVT before the knee and hip arthroplasty

PurposeTo compare the specificity and sensitivity of preoperative D-dimer and age-adjusted D-dimer value for predicting the incidence of the DVT preoperatively in total joint arthroplasty (TJA) patients.MethodsWe enrolled 406 patients finally above 50 years old. Everyone had done ultrasonography bedside, and D-dimer concentrations were collected before surgery. The D-dimer and age-adjusted D-dimer cut-off was calculated by multiple logistic regression and receiver operating curve (ROC) analyses.ResultsA total of 39 patients had found asymptomatic deep vein thrombosis (DVT) by ultrasonography. The age (odds ratio [OR] 1.067; p = 0.003) and D-dimer (OR 1.331; p = 0.025) were related to the existence of DVT. For conventional D-dimer and age-adjusted D-dimer value, the area under the curves (AUCs) were 0.685 (0.499–0.696) and 0.795 (0.611–0.881), respectively.ConclusionCompared to traditional D-dimer, age-adjusted D-dimer showed better performance in screening DVT, which was useful clinically.

Age-Adjusted D-Dimer in the Prediction of Pulmonary Embolism: Systematic Review and Meta-analysis.

Background:Pulmonary embolism (PE), depending on the severity, carries a high mortality and morbidity. Proper evaluation, especially in patients with low probability for PE, is important to avoid unnecessary diagnostic testing.Objective:To review the diagnostic utility of conventional versus age-adjusted D-dimer cutoff values in patients 50 years and older with suspected pulmonary embolism.Methods:Systematic review with univariant and bivariant meta-analysis.Data sources:We searched PubMed, MEDLINE, and EBSCO for studies published before September 20th, 2020. We cross checked the reference list of relevant studies that compares conventional versus age-adjusted D-dimer cutoff values in patients with suspected pulmonary embolism.Study selection:We included primary published studies that compared both conventional (500 µg/L) and age-adjusted (age × 10 µg/L) cutoff values in patients with non-high clinical probability for pulmonary embolism.Results:Nine cohorts that included 47 720 patients with non-high clinical probability were included in the meta-analysis. Both Age-adjusted D-dimer and conventional D-dimer have high sensitivity. However, conventional D-dimer has higher false positive rate than age-adjusted D-dimer.Conclusion:Age-adjusted D-dimer cutoffs combined with low risk clinical probability assessment ruled out PE diagnosis in suspected patients with a decreased rate of false positive tests.

Systematic Review of Aortic Dissection Detection Risk Score Plus D-dimer for Diagnostic Rule-out Of Suspected Acute Aortic Syndromes.

In patients at low clinical probability of acute aortic syndromes (AASs), decision on advanced aortic imaging is cumbersome. Integration of the aortic dissection detection risk score (ADD-RS) with D-dimer (DD) provides a potential pipeline for standardized diagnostic rule-out. We systematically reviewed and summarized supporting data. Cross-sectional studies assessing integration of ADD-RS with DD for diagnosis of AASs were identified on MEDLINE, EMBASE and Web Of Science databases. Two reviewers independently screened articles, assessed quality, and extracted data. The quality of design and reporting was evaluated with the QUADAS-2 and STARD tools. Individual patient data were obtained, to allow analysis of both conventional (500ng/mL) and age-adjusted (DDage-adj ) DD cutoffs. Data were summarized for four diagnostic strategies combining ADD-RS=0 or≤1, with DD<500ng/mL or<DDage-adj . The statistical heterogeneity of the diagnostic variables was estimated with Higgins' I2 . Pooled values were calculated for variables showing nonsignificant heterogeneity. After screening of 680 studies, four articles (including a total of 3,804 patients) met inclusion criteria. One prospective study provided a low risk of bias/applicability concerns, while methodologic limitations were found in the other three retrospective studies. Statistical heterogeneity was negligible for sensitivity and negative likelihood ratio (LR) values and significant for specificity and positive LR values of all diagnostic strategies. Pooled sensitivity was 99.9% (95% confidence interval [CI]=99.3% to 100%, I2 =0) for ADD-RS=0 and DD<500ng/mL or<DDage-adj , 98.9% (95% CI=97.9% to 99.9%, I2 =0) for ADD-RS≤1 and DD<500ng/mL, and 97.6% (95% CI=96.3% to 98.9%, I2 =0) for ADD-RS≤1 and DD<DDage-adj . Despite methodologic limitations, integration of ADD-RS=0 or≤1 with DD<500ng/mL shows negligible heterogeneity and consistently high sensitivity across studies, thus supporting reliability for diagnostic rule-out of AASs. Data supporting ADD-RS=0 plus DDage-adj appear preliminary and require further scrutiny.

Renal Function-Adjusted D-Dimer Levels in Critically Ill Patients With Suspected Thromboembolism.

Diagnosing thromboembolic disease typically includes D-dimer testing and use of clinical scores in patients with low to intermediate pretest probability. However, renal dysfunction is often observed in patients with thromboembolic disease and was previously shown to be associated with increased D-dimer levels. We seek to validate previously suggested estimated glomerular filtration rate-adjusted D-dimer cutoff levels. Furthermore, we strive to explore whether the type of renal dysfunction affects estimated glomerular filtration rate-adjusted D-dimer test characteristics. Single-center retrospective data analysis from electronic healthcare records of all emergency department patients admitted for suspected thromboembolic disease. Tertiary care academic hospital. Exclusion criteria were as follows: age less than 16 years old, patients with active bleeding, and/or incomplete records. Test characteristics of previously suggested that estimated glomerular filtration rate-adjusted D-dimer cutoff levels (> 333 µg/L [estimated glomerular filtration rate, > 60 mL/min/1.73 m], > 1,306 µg/L [30-60 mL/min/1.73 m], and > 1,663 µg/L [< 30 mL/min/1.73 m]) were validated and compared with the conventional D-dimer cutoff level of 500 µg/L. A total of 14,477 patients were included in the final analysis, with 467 patients (3.5%) diagnosed with thromboembolic disease. Renal dysfunction was observed in 1,364 (9.4%) of the total population. When adjusted D-dimer levels were applied, test characteristics remained stable: negative predictive value (> 99%), sensitivity (91.2% vs 93.4%), and specificity (42.7% vs 50.7%) when compared with the conventional D-dimer cutoff level to rule out thromboembolic disease (< 500 µg/L). Comparable characteristics were also observed when adjusted D-dimer cutoff levels were applied in patients with acute kidney injury (negative predictive value, 98.8%; sensitivity, 95.8%; specificity, 39.2%) and/or "acute on chronic" renal dysfunction (negative predictive value, 98.0%; sensitivity, 92.9%; specificity, 48.5%). D-Dimer cutoff levels adjusted for renal dysfunction appear feasible and safe assessing thromboembolic disease in critically ill patients. Furthermore, adjusted D-dimer cutoff levels seem reliable in patients with acute kidney injury and "acute on chronic" renal dysfunction. In patients with estimated glomerular filtration rate less than 60 mL/min/1.73 m, the false-positive rate can be reduced when estimated glomerular filtration rate-adjusted D-dimer cutoff levels are applied.

The Burden of Unnecessary Testing From a Regularly Ordered Laboratory Assay: Age-Adjusted d-Dimer Quality Improvement Study.

Diagnosing acute pulmonary embolism (PE) involves clinical suspicion in combination with sequential diagnostic tests including d-dimer laboratory assays. Although the sensitivity of this assay is well validated and thoroughly tested, a false-positive result can lead to unnecessary and costly testing. The age-adjusted d-dimer (AADD) has been suggested in the literature to improve the usefulness of d-dimer cutoffs and safely decrease iodine and radiation exposure associated with definitively ruling out PE with computed tomographic angiography (CTA).1 We present an internal retrospective review utilizing the novel AADD cutoff to rule out PE and evaluate the potential extent of unnecessary testing with CTA. Using the AADD cutoff would have led to a 21.2% reduction in computerized tomography pulmonary embolus protocol. This internal quality improvement study suggests that changing our institutional conventional d-dimer to the novel AADD would provide a superior quality and cost–benefit.

Diagnostic Accuracy of Age-Adjusted D-Dimer Cutoff in Suspected Cases of Pulmonary Embolism

IntroductionCurrent guidelines recommend use of clinical pretest probability scores, d-dimer assay, and imaging studies in the diagnosis of pulmonary embolism (PE). Studies have shown that normal d-dimer levels with low-intermediate probability in Wells score can safely exclude PE in most cases. Usually, d-dimer level of less than 500 µg/L is used to decide that no further imaging studies such as computed tomography pulmonary angiography (CTPA) or ventilation perfusion (V/Q) scan) are required. However, the conventional cutoff of 500 µg/L may not be as specific in all patients as d-dimer levels increase with age. Thus, use of age-adjusted d-dimer cutoff has been advocated which is defined as (age × 10) µg/L in patients 50 years or older.ObjectiveTo study if age-adjusted d-dimer is helpful in decreasing imaging studies without missing the diagnosis of PE in suspected cases.MethodsWe did an observational retrospective study of all consecutive adult patients who presented to the emergency department from January 2014 to December 2016. The patients who were clinically suspected with PE and underwent subsequent workup along with d-dimer assays were included for analysis. The number of imaging studies performed for PE diagnosis were recorded.ResultsWe included 3,197 patients in the study. Median age was 55 years, and 67% were females (Table 1). Total 2,937 (92%) patients had elevated d-dimer levels based on conventional d-dimer cutoff compared to 2,526 (79%) patients based on age-adjusted d-dimer cutoff. The age-adjusted d-dimer cutoff was more specific (21% vs 8%, p-value<0.0001) but less sensitive (100% vs 95%, p-value= 0.15) than conventional cutoff (Table 2). The use of age-adjusted d-dimer cutoff would have avoided 409 (13% of total) imaging studies (Table 3). However, 2 cases (0.7% of total) with PE, which would have underwent imaging study with conventional cutoff, would have been missed with age-adjusted d-dimer cutoff. The Wells score was 3, intermediate pretest probability, for both cases of PE.ConclusionAge-adjusted d-dimer cutoff can significantly decrease the number of imaging studies performed in cases of suspected PE. However, as shown in our study, there is a chance of missing cases with actual PE. Thus, clinicians should always be aware of a rare probability of false negative result with age-adjusted d-dimer levels. Further stratification of the probability risk or the prompt use of imaging studies in cases with higher clinical suspicion can help in accurate diagnosis of PE. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

A retrospective evaluation of the age-adjusted D-dimer versus the conventional D-dimer for pulmonary embolism.

: The conventional D-dimer cut-off value of at least 500 μg FEU/l has good sensitivity but poor specificity for identifying pulmonary embolism. An elevated age-adjusted D-dimer value (age in years × 10 μg FEU/l) for patients at least 50 years old has been recommended as a better cut-off with adequate sensitivity and improved specificity for identifying pulmonary embolism compared with the conventional value. We retrospectively reviewed 3117 patient encounters in which a D-dimer was ordered. The D-dimer value, age of the patient, and the computed tomography radiology report was evaluated. The sensitivity and specificity of the age-adjusted D-dimer was calculated using bootstrapping. With an assumed 99% sensitivity for the conventional D-dimer cut-off the specificity was 39.2% [95% confidence interval (CI): 37.5-41.0%]. The sensitivity of the age-adjusted D-dimer was 91.8% (95% CI: 83.8-97.2%) with a specificity of 51.0% (95% CI: 49.1-53.1%). The sensitivity of the age-adjusted D-dimer was unacceptably low compared with the conventional D-dimer cut-off.

Clinical usefulness and safety of an age-adjusted D-dimer cutoff levels to exclude pulmonary embolism: a retrospective analysis.

Age-adjusted D-dimer (AADD) appears to increase the proportion of patients in whom pulmonary embolism (PE) can safely be excluded compared with conventional D-dimer (CDD), according to a limited number of studies. The aim if this study was to assess whether the use of an AADD might safely increase the clinical usefulness of CDD for the diagnosis of PE in our setting. Three hundred and sixty two consecutive outpatients with clinically suspected PE in whom plasma samples were obtained to measure D-dimer were included in this post hoc analysis of a previous study. CDD cutoff value was 500 ng/mL and AADD was calculated as (patient's age × 10) ng/mL in patients aged >50. Sensitivity, specificity, clinical usefulness (i.e., proportion of true-negative tests among all patients with suspected PE), and the proportion of false negatives were calculated for both AADD and CDD among patients with low-to-moderate clinical probability of PE according to Well's criteria. PE was confirmed in 98 patients (27%). Among 331 patients with low-to-moderate clinical probability of PE, sensitivity and clinical usefulness were 100 and 27.8% for CDD, respectively, and 100 and 36.5% for AADD, respectively. In 29 patients aged >50 with CDD >500 ng/mL, AADD showed values under its normal cutoff point, without false negatives for the diagnosis of PE (0%, 95% CI 0-11%). AADD increases clinical usefulness notably with respect to that of CDD in patients with clinical suspected PE without losing sensitivity in our cohort. The use of AADD apparently does not reduce the safety of CDD for the exclusion of PE.

Diagnostic Value of Elevated D-Dimer Level in Venous Thromboembolism in Patients With Acute or Subacute Brain Lesions.

ObjectiveTo define the risk factors that influence the occurrence of venous thromboembolism (VTE) in patients with acute or subacute brain lesions and to determine the usefulness of D-dimer levels for VTE screening of these patients.MethodsMedical data from January 2012 to December 2013 were retrospectively reviewed. Mean D-dimer levels in those with VTE versus those without VTE were compared. Factors associated with VTE were analyzed and the odds ratios (ORs) were calculated. The D-dimer cutoff value for patients with hemiplegia was defined using a receiver operating characteristic (ROC) curve.ResultsOf 117 patients with acute or subacute brain lesions, 65 patients with elevated D-dimer levels (mean, 5.1±5.8 mg/L; positive result >0.55 mg/L) were identified. Logistic regression analysis showed that the risk of VTE was 3.9 times higher in those with urinary tract infections (UTIs) (p=0.0255). The risk of VTE was 4.5 times higher in those who had recently undergone surgery (p=0.0151). Analysis of the ROC showed 3.95 mg/L to be the appropriate D-dimer cutoff value for screening for VTE (area under the curve [AUC], 0.63; 95% confidence interval [CI], 0.5-0.8) in patients with acute or subacute brain lesions. This differs greatly from the conventional D-dimer cutoff value of 0.55 mg/L. D-dimer levels less than 3.95 mg/L in the absence of surgery showed a negative predictive value of 95.8% (95% CI, 78.8-99.8).ConclusionElevated D-dimer levels alone have some value in VTE diagnosis. However, the concomitant presence of UTI or a history of recent surgery significantly increased the risk of VTE in patients with acute or subacute brain lesions. Therefore, a different D-dimer cutoff value should be applied in these cases.

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.

P161 Assessment Of Age-adjusted D-dimer Cut-off Values In Investigating Venous Thromboembolism In Older Patients: A Retrospective Analysis

Introduction and objectives The specificity of D-dimer testing in detecting venous thromboembolism (VTE) appears to fall in older patients as D-dimer concentrations increase with age. There has been interest in the use of age-adjusted D-dimer cut-off values to increase the specificity in older patients. The objective of this study was to review the diagnostic accuracy of D-dimer testing in older patients with suspected VTE in our population, comparing conventional and age-adjusted D-dimer cut-off values. Methods A retrospective study from a large teaching hospital in the UK was undertaken. 389 data episodes were compiled from suspected VTE presentations during two months in 2013. Patients were assessed using a combination of clinical probability scores and D-dimer measurement (D-dimer HS assay, Instrumentation Laboratories). Conventional (230 ng/ml) and age-adjusted (age x 10 ng/ml) cut-off values were applied to patients ≥50 years, and specificity and sensitivity were calculated. Results (Table 1) Of the 389 presentations, 229 (58.9%) were from patients aged ≥50 years. 13 (11.5%) patients with positive D-dimers using the conventional cut-off, had VTE as confirmed by imaging tests. The sensitivity of the conventional D-dimer cut-off value was 100% in this older cohort, with a specificity of 53.7%. The age x10-adjusted cut-off improved specificity to 84.7%; however sensitivity was markedly reduced to 76.9%, with 3 patients (23.1%) with non-high clinical probability of VTE missed. Further analysis suggested that an age-adjusted cut-off factor of x3 would maintain sensitivity at 100%; however specificity was only 47.7%. Conclusions We have identified that an age-adjusted cut-off factor of x10 significantly increased D-dimer specificity in older patients; however the sensitivity of this test was unacceptably compromised. A cut-off factor of x3 maintained sensitivity, but specificity was unsatisfactory compared to conventional values, although still higher than in most published series. We conclude that we cannot use an age-adjusted cut-off of x10 in our ≥50 year old population using this assay. Further work is required to identify an appropriate cut-off, concentrating on the >75 year old patients only. This would help to reduce the number of unnecessary tests and anxiety in this vulnerable group of patients.

The combination of four different clinical decision rules and an age-adjusted D-dimer cut-off increases the number of patients in whom acute pulmonary embolism can safely be excluded

Four clinical decision rules (CDRs) (Wells score, Revised Geneva Score (RGS), simplified Wells score and simplified RGS) safely exclude pulmonary embolism (PE), when combined with a normal D-dimer test. Recently, an age-adjusted cut-off of the D-dimer (patient's age x 10 μg/l) safely increased the number of patients above 50 years in whom PE could safely be excluded. We validated the age-adjusted D-dimer test and assessed its performance in combination with the four CDRs in patients with suspected PE. A total of 414 consecutive patients with suspected PE who were older than 50 years were included. The proportion of patients in whom PE could be excluded with an 'unlikely' clinical probability combined with a normal age-adjusted D-dimer test was calculated and compared with the proportion using the conventional D-dimer cut-off. We assessed venous thromboembolism (VTE) failure rates during three months follow-up. In patients above 50 years, a normal age-adjusted D-dimer level in combination with an 'unlikely' CDR substantially increased the number of patients in whom PE could be safely excluded: from 13-14% to 19-22% in all CDRs similarly. In patients over 70 years, the number of exclusions was nearly four-fold higher, and the original Wells score excluded most patients, with an increase from 6% to 21% combined with the conventional and age-adjusted D-dimer cut-off, respectively. The number of VTE failures was also comparable in all CDRs. In conclusion, irrespective of which CDR is used, the age-adjusted D-dimer substantially increases the number of patients above 50 years in whom PE can be safely excluded.

A New Quantitative D-dimer Assay Appropriate in Emergency: Reliability of the Assay for Pulmonary Embolism Exclusion Diagnosis

Plasma D-dimers, degradation products of cross-linked fibrin, are elevated in several thrombotic diseases. In the last decade, their measurement has been performed with specific monoclonal antibody based ELISA assay, with a high negative predictive value of such pathologies. However these methods have a low clinical impact since they cannot be used in emergency because they are time consuming and require series. Recently, rapid tests have been proposed with similar accuracy and are feasible for use in emergency conditions. The aim of our study was to evaluate the potential value of a new quantitative rapid assay, based on agglutination of latex microparticles coated with two monoclonal antibodies specific for D-dimers (Liatest D-Di, Diagnostica Stago), in the exclusion diagnosis of pulmonary embolism (PE). Eighty-five consecutive suspected PE patients were included in the study. D-dimer determination was performed with both standard ELISA and Liatest D-Di just before pulmonary scintigraphy. Sixty-nine patients were free of PE and 16 had PE. Our results confirm the excellent sensitivity and negative predictive values of the conventional D-dimer ELISA. Using a cut-off value of 500 ng/ml, the sensitivity and the negative predictive values of Liatest D-Di were 94% and 96%, respectively. Only one case of PE had a D-dimer value at 480 ng/ml, close to the cut-off value. This study demonstrates that the Liatest D-Di assay is sensitive enough to be used as the first step in the assessment of PE. However, the best cut-off value has to be determined to get an exclusion diagnosis with certainty.