Evaluation of a new rapid D-dimer assay for clinically suspected deep venous thrombosis (Liatest D-dimer)

Sex Differences in Clinical Presentation of Lower Extremity Deep Vein Thrombosis

Background: Differences between men and women in the clinical features and extent of lower limb deep vein thrombosis (DVT) may influence DVT diagnostic algorithms involving pretest clinical probability (PTP) assessment, D-dimer, and compression ultrasonography (CUS). Aims: To assess differences in DVT clinical presentation between men and women and their effect on PTP and D-dimer. Methods: We conducted a retrospective study in outpatients referred for suspected DVT of the lower limbs to our vascular emergency department from January 2005 to December 2019. Patients underwent PTP assessment with the Wells score, D-dimer testing, and CUS. Results: More women were referred for suspected DVT than men (M/F: 1,785/2,821; F: 61.4%; p < 0.0001). Women were older than men (median age: 71 vs. 67 years; p = 0.0001), DVT was diagnosed in 436 patients (9.4%) but in more men than women (M: 210 [11.8%] vs. F: 226 [8%]; p = 0.0002), with more proximal DVT in men than women (M: 131 7.3% vs. F: 124 [4.4%]; p = 0.00021). PTP was more likely in men (355 [19.9%]) than women (455 [16.2%]) (p = 0.0011); more men had swelling in the entire limb, increased calf circumference by >3 cm compared with the contralateral limb, and pitting edema, than women. D-dimer levels (available in 65% of patients) were more frequently positive in women with DVT than in men (94.6% vs. 85.7%; p = 0.016). However, a positive D-dimer and/or likely PTP was similarly frequent in men (92%) and women (96%) with DVT. Conclusions: More women than men are referred for suspected DVT, and men have a higher prevalence of proximal DVT. However, current algorithms for DVT diagnosis perform similarly in men and in women.

Point-of-Care Platform for Diagnosis of Venous Thrombosis by Simultaneous Detection of Thrombin Generation and D-Dimer in Human Plasma

Venous thromboembolism (VTE) refers to a blood clot that starts in a vein. The risk of developing VTE is highest after major surgery or a major injury, or when someone has heart failure, cancer, or infectious disease (e.g., COVID-19). Without prompt treatment to break up clots and prevent more from forming, VTE can restrict or block blood flow and oxygen, which can damage the body tissue or organs. VTE can occur without any obvious signs, and imaging technologies are used. Alternatively rapid measurement of thrombin generation (TG) and D-dimer could be used to make a fast, portable, and easy-to-use diagnostic platform for VTE. Here, we have demonstrated a diagnostic sensing platform with the ability of simultaneous detection of TG and D-dimer in human plasma. Modifications were made to both the assay protocols to eliminate the need for sample dilution and incubation steps. Using a substantially reduced sample volume, the measurement results show comparable performance to the gold standard method. Our platform is able to deliver accurate and cost-effective results for both TG and D-dimer assays when using undiluted plasma in under 15 min. The assays presented are therefore a good candidate technology for use in a point-of-care platform to diagnose VTE.

Biosensing of D-dimer, making the transition from the central hospital laboratory to bedside determination

Since the disclosure of the fibrinogen degradation mechanism, around half a century ago, a significant number of papers have been published related to the clinical relevance of D-dimer, a molecule immune to additional enzymatic decomposition by plasmin. Due to the obliquity of regulating blood coagulation in pathological events, the number of diseases and conditions associated with abnormal levels of D-dimer includes deep vein thrombosis, pulmonary embolism, sepsis, myocardial infarction, disseminated intravascular coagulation, among many others. D-dimer not only is an important player in medical diagnosis but also its role as a prognosis biomarker is being revealed. However, the number of analytical alternative methods has not accompanied this trend, even though novel simple point-of-care devices would certainly boost the relevance of D-dimer in emergency medicine. Some reasons for that could be related to the fact that D-dimer is a challenging analyte present in complex samples like blood. In this manuscript, subsequent to a fibrinogen degradation process introduction, it is provided a historical overview of the early D-dimer assays, followed by an extended focus on innovative solutions, with a spotlight on the electrochemical bioanalytical devices. The discussion is accompanied with a critical analysis and concluding thoughts concerning future perspectives.

Association between plasma levels of D-dimer and fibrinogen/fibrin degradation products (FDP) for exclusion of thromboembolic disorders

BACKGROUND

D-dimer and fibrinogen/fibrin degradation products (FDP) levels are elevated in subjects with thromboembolic disorders, and the assays for detection of D-dimer and FDP are used in many laboratories for the investigation of these disorders. The aim of this study was to evaluate the association between the plasma levels of D-dimer and FDP in the investigation of thromboembolic disorders.

METHODS

D-dimer and FDP immunoassays were performed in 217 consecutive blood samples from subjects with suspected of thromboembolic disorders by use of Liatest D-dimer and Plasma FDP.

RESULTS

FDP results were classified in: <5, 5-20, >20 microg/mL, and D-dimer levels obtained in these groups ranged to 350-1,210 ng/mL, 420-1,960 ng/mL, and 1,190-51,170 ng/mL, respectively. A significant association between D-dimer levels and the reaction times necessary to occur agglutination in latex agglutination test for FDP was observed.

CONCLUSIONS

There was an association between plasma levels of D-dimer and FDP. The preliminary determination of FDP levels could be useful because it allows estimating the D-dimer levels before of the automated systems analysis, reducing costs associated to dilutions of plasma samples.

The Wells rule and D-dimer for the diagnosis of isolated distal deep vein thrombosis

BACKGROUND

Pretest clinical probability with the Wells rule and D-dimer have been widely investigated for the diagnosis of symptomatic proximal deep vein thrombosis (DVT) of the lower limbs, but they have not been formally tested for symptomatic isolated distal DVT diagnosis.

OBJECTIVE

To evaluate the diagnostic accuracy of the Wells rule and D-dimer for isolated distal DVT.

DESIGN, SETTING, AND PATIENTS

This was a single-center, cross-sectional study including 873 consecutive outpatients with suspected DVT, in whom pretest clinical probability determination, D-dimer determination (STA Liatest; cut-off of < 500 ng mL(-1) ) and complete compression ultrasonography of both lower limbs were performed.

RESULTS

The isolated distal DVT prevalence was 12.4% (90/725). The sensitivity of the Wells rule for isolated distal DVT was 47% (95% confidence interval [CI] 36-57%), the specificity was 74% (95% CI 70-77%), and the negative and positive predictive values were 91% (95% CI 88-93%) and 20% (95% CI 15-26%), respectively. Patients with isolated distal DVT had higher D-dimer levels than patients without DVT (1759 ± 1576 vs. 862 ± 1079 ng mL(-1) , P = 0.0001). D-dimer was negative in 13 patients with isolated distal DVT. D-dimer sensitivity and specificity for isolated distal DVT were 84% (95% CI 75-91%) and 50% (95% CI 46-54%), respectively, with a negative predictive value of 96% (95% CI 93-98%). In patients with low pretest clinical probability, the D-dimer negative predictive value was 99% (95% CI 95-100%).

CONCLUSION

In clinically suspected DVT with negative proximal compression ultrasonography, pretest clinical probability with the Wells rule has a low diagnostic accuracy for isolated distal DVT. D-dimer has a better negative predictive value, but alone it does not exclude isolated distal DVT. In patients with low pretest clinical probability, D-dimer had a negative predictive value of > 95% for isolated distal DVT.

D-Dimer for venous thromboembolism diagnosis: 20 years later

Twenty years after its first use in the diagnostic workup of suspected venous thromboembolism (VTE), fibrin D-dimer (DD) testing has gained wide acceptance for ruling out this disease. The test is particularly useful in the outpatient population referred to the emergency department because of suspected deep vein thrombosis (DVT) or pulmonary embolism (PE), in which the ruling out capacity concerns every third patient clinically suspected of having the disease. This usefulness is based on the high sensitivity of the test to the presence of VTE, at least for some assays. Due to its poor specificity precluding its use for ruling in VTE, DD testing must be integrated in comprehensive, sequential diagnostic strategies that include clinical probability assessment and imaging techniques such as lower limb venous compression ultrasonography for suspected DVT or multi-slice helical computed tomography for suspected PE. The present narrative review updates the data available on the use of the various commercially available DD assays in the diagnostic approach of clinically suspected VTE in distinct patient populations or situations, including outpatients and inpatients, patients with cancer, older age, pregnancy, a suspected recurrent event, limited thrombus burden, and patients already on anticoagulant treatment.

Performance evaluation of a new rapid quantitative assay system for measurement of D-dimer in plasma and whole blood: PATHFAST™ D-dimer

D-dimer is an indicator for in vivo fibrin formation, reflecting the formation of fibrin crosslinked by factor XIIIa. D-dimer assays are frequently used in emergency situations, such as diagnosis of venous thrombosis and pulmonary embolism, or disseminated intravascular coagulation. In these conditions, short sample turnaround times are essential. The PATHFAST D-dimer assay allows rapid quantitative measurement of D-dimer in plasma and whole blood. The study shows an excellent correlation between whole blood and plasma measurement of D-dimer both in the high range, as well as in the normal range. Intra-assay and inter-assay coefficients of variation (CV) were below 10%. The upper limit of normal (ULN = mean value measured in 100 samples from healthy blood donors + 2 x S.D.) was approximately 1 microg/ml FEU, using the assay-specific calibration. The maximal value measured in 20 replicates of calibrator 1 containing no D-dimer antigen was 0.00052 microg/ml FEU, and this 10-fold lower than the declared detection limit of 0.005 microg/ml FEU. In conclusion, the PATHFAST D-dimer assay is the first automated fully quantitative D-dimer assay, which can use plasma and whole blood as sample materials in parallel.

Estimation of the levels of D-dimer by use of an alternative method based in the reaction time of fibrinogen/fibrin degradation products assay

BACKGROUND

D-dimer and fibrinogen/fibrin degradation products (FDP) levels are elevated in thromboembolic disorders, and its assays are used in many laboratories for the investigation of these disorders. The aim of this study was to propose a cost saving alternative method for determination of D-dimer levels based in the reaction time of FDP assay.

METHODS

D-dimer and FDP immunoassays were performed in 100 blood samples from subjects by use of Liatest D-dimer and Plasma FDP. The results of D-dimer obtained by the Liatest D-dimer were compared with the results obtained by the estimation method.

RESULTS

A significant association between D-dimer levels and the reaction times necessary to occur agglutination in latex agglutination test for FDP was observed. A close agreement between D-dimer results obtained by the Liatest D-dimer and by the estimation method (D-dimer = 82829 FDPt(-0.8683)) was observed.

CONCLUSIONS

The estimation method described in this study could be useful for clinical laboratories because it allows estimating the D-dimer levels before of the automated systems analysis, reducing costs associated to dilutions of plasma samples and reagents.

Diagnostic value of D-dimer in patients with suspected pulmonary embolism: results from a multicentre outcome study

BACKGROUND

D-dimer tests are used in various diagnostic strategies to exclude pulmonary embolism (PE). However, their role as an exclusionary first-line test is still uncertain, mainly because accuracy of the test varies according to the assay and the studied population.

METHODS

The aim of this multicentre study was to evaluate the accuracy of D-dimer testing in patients with suspected PE. Diagnosis of PE was based on pre-test clinical probability (PCP) evaluation and both single-detector spiral CT (CT) and lower limbs compression ultrasonography (CUS). Lung scanning and/or pulmonary angiography was mandatory when CT or CUS was inconclusive and when both CT and CUS were normal in a patient with a high PCP. All patients were followed-up for 3 months, looking for VTE recurrence. D-dimers were collected within 24 h of inclusion and stored in each local hematology unit, to be analyzed at the end of all inclusions; physicians in charge of the patient were blinded to D-dimer results.

RESULTS

Three hundred and fifty two patients were included in 4 centres. Prevalence of PE was 38.6%. PCP was low in 82 (23.3%), intermediate in 176 (50%) and high in 94 (26.7%) patients. Sensitivity of D-dimer was 96.3% (95% CI: 93-99) and negative predictive value reached 94.4% (95% CI: 90-99). Five patients with a confirmed PE had a D-dimer level below 500 ng/ml (two patients with a high PCP). Among 258 patients with low or intermediate PCP, 80 (31%) had a negative D-dimer test result; three of them had a false negative result and the number needed to test was 3.3. Among 94 patients with a high PCP, 9 had a negative D-dimer test result; two of them had a false negative result and the number needed to test was 13.5.

CONCLUSION

These results confirm that rapid assays used in this study can safely exclude PE in first-line testing only in non-high CP patients.

Diagnostic and prognostic value of circulating D-Dimers in patients with acute aortic dissection

OBJECTIVE

We sought to determine whether assessing D-Dimer might be helpful for the management of acute aortic dissection (AAD).

DESIGN

Single-center retrospective case-control study.

SETTING

University Hospital of Strasbourg France.

PATIENTS

Patients were 94 consecutive patients admitted to our institution with confirmed AAD and in whom D-Dimer test had been performed at presentation. These patients were matched with 94 controls presenting with clinical suspicion of dissection, which was later ruled out.

INTERVENTIONS

Patient characteristics and clinical course were analyzed.

MEASUREMENTS AND MAIN RESULTS

Ninety-three (99%) patients with AAD had elevated D-Dimer (>400 ng/mL) with a median D-Dimer value of 8610 ng/mL (interquartile range, 2982-20,000 ng/mL). Receiver operating characteristic curves analysis showed that D-Dimer, but not C-reactive protein, troponin, lactate dehydrogenase, or leukocyte count, was predictive of a diagnosis of AAD, with a sensitivity and specificity of 99% and 34%, respectively. D-Dimer concentration positively correlated with the anatomical extension of the dissection to the different segments of the aorta (R = .47, p < .0001). A positive relationship was observed between D-Dimer and in-hospital mortality rate among patients with AAD (p = .037). On multivariate analysis, the independent predictors of in-hospital mortality were the presence of pericardial effusion (odds ratio, 6.80; confidence interval, 1.87-27.60), D-Dimer >5200 ng/mL (odds ratio, 5.38; confidence interval, 1.27-30.87), and female gender (odds ratio, 4.96; confidence interval, 1.39-19.95).

CONCLUSIONS

D-Dimers are elevated in patients with AAD and provide valuable diagnostic and prognostic information. In patients with acute chest pain and elevated D-Dimer, a diagnosis of AAD should also be considered. D-Dimer might be a useful complementary tool to the current diagnostic work-up of patients with suspected AAD.

The potential of D-dimer levels as a useful clinical marker of clotting state after the return of sinus rhythm

Fibrin d-dimers levels have been advocated as a useful clinical marker of thrombogenesis. It is accepted that patients with atrial fibrillation (AF) are characterized by increased levels of plasmatic d-dimers. AF is a high risk factor for hypercoagulability, with a substantial risk of thromboembolism. The most effective way of minimizing the increased thromboembolic risk and treating patients’ symptoms is to return the heart rhythm to sinus rhythm by electrical or chemical cardioversion. However, cardioversion of AF itself leads to a further increased risk of thromboembolism. A marker of coagulation activation would be useful to identify patients at the highest thromboembolic risk after cardioversion in AF patients. Indicators of hypercoagulability, such as d-dimers, appear to be a useful parameter for assessing the degree of hypercoagulability of AF patients after cardioversion. Mean changes in plasma d-dimers levels could be used as a useful clinical marker of the clotting state after the return of atrial systole.

A negative D-dimer assay does not rule out cerebral venous thrombosis: a series of seventy-three patients

BACKGROUND AND PURPOSE

Cerebral venous thrombosis (CVT) is an infrequent variety of cerebrovascular disease with a wide spectrum of clinical presentations and a notoriously difficult diagnosis. Previous reports have emphasized the potential clinical utility of D-dimer assay in CVT diagnosis.

METHODS

A rapid sensitive D-dimer assay was performed at entry in 73 patients with CVT <30 days duration, examined in our institution between 1999 and 2003.

RESULTS

The mean value of D-dimer levels was 1521 ng/mL; 7 patients (10% of all patients and 26% of those presenting with isolated headache) had values <500 ng/mL. In a multivariate analysis, isolated headache was the only variable associated with a negative D-dimer assay.

CONCLUSIONS

A negative D-Dimer assay does not confidently rule out CVT, particularly in the setting of recent isolated headache.

Variation in the diagnostic performance of D-dimer for suspected deep vein thrombosis

BACKGROUND

Numerous studies have evaluated the accuracy of D-dimer in diagnosing suspected deep vein thrombosis (DVT), but results are conflicting.

AIM

To overview estimates of the diagnostic accuracy of D-dimer and identify causes of variation.

DESIGN

Systematic review, meta-analysis and meta-regression.

METHODS

We searched Medline, EMBASE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, Database of Reviews of Effectiveness, the ACP Journal Club, citation lists, and contacted manufacturers. We selected studies that compared D-dimer to a reference standard in patients with suspected DVT. Data were analysed by random effects meta-analysis and meta-regression.

RESULTS

We included 97 studies reporting 198 assays in 99 different patient groups. Overall estimated sensitivity and specificity of D-dimer were 90.5% and 54.7%, but both estimates were subject to significant heterogeneity (p < 0.001). Meta-regression identified that some heterogeneity was explained by study setting, exclusion criteria, whether recruitment was consecutive or the study prospective, whether D-dimer and the reference standard were measured blind, and whether the D-dimer threshold was determined a priori. Sensitivity and specificity also varied between ELISA (94% and 45% respectively), latex (89% and 55%) and whole blood agglutination assays (87% and 68%). Sensitivity was higher for proximal than distal DVT. Specificity was dependent upon whether clinical probability of DVT was high (specificity 51%), intermediate (67%) or low (78%).

DISCUSSION

D-dimer has good sensitivity, but poor specificity, for DVT. Estimates are subject to substantial heterogeneity from various sources. D-dimer specificity appears to be strongly dependent upon the pre-test clinical probability of DVT.

Clotting state after cardioversion of atrial fibrillation: a haemostasis index could detect the relationship with the arrhythmia duration

Background

Fibrin D-dimer levels have been advocated as an useful clinical marker of thrombogenesis.

Hypothesis

We hypothesized that i) there is a hyperclotting state after the return of atrial fibrillation to sinus rhythm, ii) the measurement of plasma D-Dimer levels might be a good screening tool of this clotting status, and iii) the duration of arrhythmia influences the haemostasis measured by plasma D-Dimer levels.

Methods

Forty-two patients with atrial fibrillation undergoing cardioversion were divided into two groups: in Group A (n = 24,14 male, 56 ± 11 years) the duration of atrial fibrillation was 72 hours or more (142.7 ± 103.8 hours), in Group B (n = 18, 10 male, 61 ± 13 years) the duration of atrial fibrillation was less than 72 hours (25 ± 16 hours). Plasma fibrin D-dimer levels were measured by enzyme immunoassay before, and 36 hours after, cardioversion. The change of plasma D-dimer levels 36 hours after cardioversion was calculated as delta-D-dimer.

Results

There were no significant differences in demographic, clinical, and echocardiographic data, and the success of cardioversion between the two groups. Compared to the control, the baseline D-dimer levels were significantly higher in both groups. The delta D-dimer levels were significantly higher in Group A than in Group B (p < 0.005). Furthermore, plasma D-dimer levels 36 hours after cardioversion (r = 0.52, p = 0.0016) and delta-D-dimer levels (r = 0.73, p < 0.0001) showed significant correlations with the duration of atrial fibrillation.

Conclusion

The longer duration of the atrial fibrillation episode could lead to a more prominent cardiovascular hyperclotting state after cardioversion, and the mean changes of plasma D-Dimer levels could be used as an useful clinical marker of the clotting state after atrial systole return.

Performance of the automated and rapid STA Liatest D-dimer on the STA-R analyzer

OBJECTIVE

The aim of the present study was to investigate the accuracy indices of the new automated and rapid microlatex D-dimer assay, STA Liatest D-Di, on the STA-R analyzer and to compare it with established D-dimer assays.

METHODS

D-dimer testing has been performed in 103 consecutive outpatients with suspected deep venous thrombosis (DVT). Diagnosis of DVT was established by contrast venography or color-coded duplex ultrasonography. D-dimers plasma concentrations were measured with the STA Liatest D-Di on the STA-R coagulation analyzer, with a reference ELISA technique (Asserachrom), with an automated quantitative latex-based immunoassay (Tinaquant) and with the VIDAS D-dimer test.

RESULTS

In total, 103 eligible outpatients entered the current study and DVT was detected in 46 patients (44.6%). Two duplicate D-dimer measurement with the STA Liatest D-Di revealed excellent correlation (r(S)=0.996) and almost identical sensitivity (each 98%), specificity (49% and 50%), negative predictive value (NPV; each 97%), positive predictive value (PPV; 61% and 62%) and exclusion rate (27% and 28%), respectively. Comparison of the STA Liatest D-Di with the other D-dimer tests revealed highly significant correlations (r(S)=0.951-0.979), highly comparable regression and excellent agreement in clinical interpretation of the test results (kappa coefficients 0.812-0.856). Moreover, sensitivity, specificity, NPV, PPV and exclusion rate at a cut-off level of 500 ng/ml were in the same range for the STA Liatest D-Di when compared with the other D-dimer tests.

CONCLUSION

The Liatest D-Di performed on the coagulation analyzer STA-R compares favorable with the VIDAS, Tinaquant and Asserachrom D-dimer tests and is suitable for the safe exclusion of DVT in symptomatic outpatients. The test can be included in an algorithm for DVT diagnosis including other diagnostic tools.

Combined use of rapid D-dimer testing and estimation of clinical probability in the diagnosis of deep vein thrombosis: systematic review

OBJECTIVE

To summarise the evidence supporting the use of rapid d-dimer testing combined with estimation of clinical probability to exclude the diagnosis of deep venous thrombosis among outpatients.

DATA SOURCES

Medline (June 1993 to December 2003), the Database of Abstracts and Reviews (DARE), and reference lists of studies in English.

SELECTION OF STUDIES

We selected 12 studies from among 84 reviewed. The selected studies included more than 5000 patients and used a rapid D-dimer assay and explicit criteria to classify cases as having low, intermediate, or high clinical probability of deep vein thrombosis of the lower extremity among consecutive outpatients.

REVIEW METHODS

Diagnosis required objective confirmation, and untreated patients had to have at least three months of follow up. The outcome was objectively documented venous thromboembolism. Two authors independently abstracted data by using a data collection form.

RESULTS

When the less sensitive SimpliRED D-dimer assay was used the three month incidence of venous thromboembolism was 0.5% (95% confidence interval 0.07% to 1.1%) among patients with a low clinical probability of deep vein thrombosis and normal D-dimer concentrations. When a highly sensitive D-dimer assay was used, the three month incidence of venous thromboembolism was 0.4% (0.04% to 1.1%) among outpatients with low or moderate clinical probability of deep vein thrombosis and a normal D-dimer concentration.

CONCLUSIONS

The combination of low clinical probability for deep vein thrombosis and a normal result from the SimpliRED D-dimer test safely excludes a diagnosis of acute venous thrombosis A normal result from a highly sensitive D-dimer test effectively rules out deep vein thrombosis among patients classified as having either low or moderate clinical probability of deep vein thrombosis.

D-dimer testing for deep venous thrombosis: a metaanalysis

BACKGROUND

The use of D-dimer assays as a rule-out test for deep venous thrombosis (DVT) is controversial. To clarify this issue we performed a systematic review of the relevant literature.

METHODS

We identified eligible studies, using MEDLINE entries from February 1995 through October 2003, supplemented by a review of bibliographies of relevant articles. Studies reporting accuracy evaluations comparing D-dimer test results with lower extremity ultrasound or venography in symptomatic patients with suspected acute DVT were selected for review. Two reviewers critically appraised each study independently according to previously established methodologic standards for diagnostic test research. Those studies judged to be of highest quality were designated Level 1.

RESULTS

The 23 Level 1 studies reported data on 21 different D-dimer assays. There was wide variation in assay sensitivity, specificity, and negative predictive values, and major differences in methodology of reviewed studies. A multivariate analysis of assay performance, controlling for sample size, DVT prevalence, reference standard, and patient mix, found few differences among the assays in effect on test performance as measured by diagnostic odds ratio. Increasing prevalence of DVT was associated with poorer test performance (P = 0.01), whereas the choice of venography as the reference standard was associated with better test performance (P <0.005).

CONCLUSIONS

Explanations for the wide variation in assay performance include differences in biochemical and technical characteristics of the assays, heterogeneity and small size of patient groups, and bias introduced by choice of reference standards. Assay sensitivity and negative predictive value were frequently <90%, uncharacteristic of a good rule-out test. General use of D-dimer assays as a stand-alone test for the diagnosis of DVT is not supported by the literature.

A rapid quantitative turbimetric d-dimer assay has high sensitivity for detection of pulmonary embolism in the ED

Many rapid d-dimer assays are commercially available with wide ranges of reported sensitivities, often based on small sample sizes. This has limited their intended use as rapid and inexpensive tests to evaluate pulmonary embolism in the low-risk patient. We sought to determine the sensitivity of the STA-Liatest D-Di d-dimer assay in our ED. We performed a retrospective analysis of 103 patients seen in our ED with the admitting diagnosis of known or suspected pulmonary embolism. These charts were assessed to establish if a d-dimer assay was performed within 24 hours. These charts were then reviewed to determine what diagnostic studies were performed and what final diagnosis was reached. Of the 103 charts identified, 55 had d-dimer assays performed within 24 hours. Of those, 38 were diagnosed with pulmonary embolism; none had negative d-dimer assays (<400 ng/mL). Using the exact method, the sensitivity of this assay was calculated to be 100% with a 95% confidence interval (CI) of 91.4% to 100%. Our results suggest that the STA-Liatest D-Di d-dimer assay could have an adequate sensitivity to be used to rule out pulmonary embolism in low-risk patients. Further prospective studies with larger sample sizes are required to validate this observation.

Comparison of diagnostic accuracies in outpatients and hospitalized patients of D-dimer testing for the evaluation of suspected pulmonary embolism

BACKGROUND

The ability of various D-dimer assays to exclude the diagnosis of thromboembolic diseases is controversial. We examined the diagnostic accuracy of two D-dimer methods in hospitalized patients and outpatients.

METHODS

We studied consecutive patients for whom D-dimer testing was ordered for investigation of suspected pulmonary embolism. We measured D-dimer by an ELISA (VIDAS D-dimer) and an enhanced microlatex immunoassay method (Diagnostica Stago STA Liatest D-di). Patient diagnoses were based on imaging studies or, when these were not performed, on follow-up by review of medical records 3 months later.

RESULTS

We examined 233 hospitalized patients and 234 outpatients with a mean age of 58 years (range, 1-92 years) and a female-to-male ratio of 1.4 to 1. Thromboembolism was present in 8% of outpatients and 12% of hospitalized patients. In outpatients, the negative predictive values were 98% [95% confidence interval (CI), 93-100%] and 99% (94-100%) for the microlatex and ELISA methods, respectively, at the recommended cutoffs. Areas under the ROC curves were similar for the two methods [0.77 (95% CI, 0.67-0.87) and 0.81 (0.73-0.89), respectively]. By contrast, in hospitalized patients, the confidence intervals for the areas under the ROC curves included 0.5 [0.60 (95% CI, 0.50-0.71) and 0.56 (0.44-0.67)].

CONCLUSIONS

For hospitalized patients, in contrast to outpatients, the diagnostic accuracy of D-dimer testing for pulmonary embolism is poor in a tertiary care setting, presumably reflecting thrombosis and comorbidities, other than pulmonary embolism, that increase the D-dimer concentrations in these patients. The patient population studied appears more important than assay method in studies of the diagnostic accuracy of D-dimer testing.

The usefulness of five D-dimer assays in the exclusion of deep venous thrombosis

D-Dimer measurement is a promising tool in the exclusion of venous thrombosis. New d-dimer assays have been introduced, but need clinical validation. Our objective was to evaluate the clinical usefulness of four relatively new d-dimer assays and a classical ELISA in outpatients suspected for deep venous thrombosis. In 537 patients, participants in a large prospective management study using a clinical probability score and a d-dimer measurement (Tina-quant), additional samples were taken for d-dimer measurement using the Asserachrom ELISA, the VIDAS New, the STA-LIA and the Miniquant assay. Performances of each test were calculated using clinical data during a 3-month follow-up. Thrombosis was detected in 224 patients (42%). The area under the ROC curve was significantly higher for the Tina-quant as compared to the other assays. Using standard cut-off values, sensitivity, negative predictive value (NPV) and specificity of the Asserachrom were 97, 94 and 33%, respectively. For the VIDAS New, values were 100, 96 and 8%, respectively. The Tina-quant showed values of 99, 98 and 41%, respectively, and the STA-LIA 98, 95 and 32%. Values for the Miniquant were 95, 94 and 52%. The d-dimer assays in our study all show a high sensitivity and negative predictive value, but none of the assays reached an NPV of > 98% at standard cut-off values. d-Dimer assays with a low specificity still necessitate additional diagnostic tests in the majority of the patients.

D-dimer and its relationship to fibrinogen/fibrin degradation products (FDPs) in disorders associated with activation of coagulation or fibrinolytic systems

Levels of D-dimer and fibrinogen/fibrin degradation products (FDPs) are significantly elevated in patients with deep venous thrombosis, pulmonary embolism, disseminated intravascular coagulation, or other complications. The diagnosis of these disorders can be difficult, time-consuming, and expensive. Assays for the detection of FDPs and D-dimer are used in many laboratories to investigate these disorders. The aim of this study was to compare plasma D-dimer levels obtained by the immuno-turdimetric method (Liatest D-Dimer Diagnostica Stago, Asnières, France) with plasma FDPs were measured by latex agglutination to investigate the relationship between these parameters. These immunoassays were tested in 144 blood samples from patients with suspected disorders associated with activation of coagulation or fibrinolytic systems. D-dimer and FDPs assays were performed in plasma samples by the use of Liatest D-dimer and plasma FDPs (Diagnostica Stago), respectively. Patients were divided into four groups according to plasma D-dimer levels. In group 1, 47.4% had negative FDPs and 52.6% had positive FDPs. In group 2, 15.4% had negative FDPs and 84.6% had positive FDPs. In group 3, 10.3% had negative FDPs and 89.7% had positive FDPs. All of the patients in group 4 had positive FDPs. It was shown that plasma D-dimer levels measured by Liatest D-dimer have a relation to FDP levels measured by latex agglutination.

The d-dimer test for deep venous thrombosis: gold standards and bias in negative predictive value

BACKGROUND

Because venous ultrasound (US) fails to fully image the calf veins, there is the potential for US gold standard studies to classify patients with calf deep venous thrombosis (DVT) in the nondiseased category, causing bias in test index calculations. A false increase in negative predictive value (NPV) is especially likely because calf DVT false-negative tests will be counted in the numerator along with the true-negative tests in NPV calculations. We verified the presence and magnitude of this bias for the d-dimer test.

METHODS

We abstracted data on overall (calf and thigh) and thigh-only test sensitivity, specificity, and NPV from the six English language studies published between March 1995 and October 2001 that compared d-dimer to a gold standard (GS) capable of imaging both thigh and calf veins and that also stratified results by thigh and calf location. Thigh specificity and NPV were calculated classifying calf DVT patients as free of disease.

RESULTS

The six studies included 81-214 participants and provided 26 comparisons of 16 different d-dimer assays to the GS. Thigh sensitivity was higher than overall sensitivity in 22 of 26 comparisons (range, -0.3 to 8.6); thigh specificity was lower than overall specificity in all comparisons (range, -0.7 to -7.8); and thigh NPV was higher than overall NPV in 22 of 26 comparisons and unchanged in 4 comparisons (range, 0.0-9.2). NPV was >95% in 20 of the thigh results but >95% in only 8 of the overall results.

CONCLUSIONS

Different GS can produce clinically significant differences in test indices. Care must be taken in interpreting DVT studies that evaluate d-dimer as a rule-out test and that use US as a GS, because missed calf DVT can falsely increase the NPV.

D-dimer: a characteristic of the coagulation state of each patient with chronic atrial fibrillation

BACKGROUND AND OBJECTIVE

It is accepted that patients with atrial fibrillation (AF) are characterised by increased levels of plasmatic D-dimers, with a wide inter-individual variability depending on the patients and therapeutic characteristics, but it has not been established if this level was predictive of the risk of arterial thromboembolic event. In order to answer such a question, it has to be established if the D-dimer level in a given patient is characteristic of such a patient (stable over time) if also fluctuating with time (and useless to characterise the patient).

METHODS AND RESULTS

One hundred thirty clinically stable patients with chronic AF were recruited (anticoagulant: group 1, antiaggregant aspirin: group 2, no antithrombotic: group 3). During the follow-up of patients without clinical events (n=63), it is notable that in patients with D-dimer levels <500 ng/ml, these remained <1000 ng/ml, in patients with levels between 500 and 1000 ng/ml, these did not reach 1590 ng/ml, and in those with D-dimers >1000 ng/ml, the levels remained relatively stable. Mean age and D-dimer levels were lower in group 1 (74.4 years and 509.1 ng/ml, respectively) than in group 2 (82.4 years, p=0.0003 and 1015.7 ng/ml, p<0.0001, respectively) and in group 3 (79.3 years and 1289.3 ng/ml, p<0.0001, respectively). The effect of the antithrombotic therapy was independent of the age of patients (p=0.017).

CONCLUSION

D-dimer levels in patients with chronic AF remain in the same range over time. They are lower on anticoagulant therapy than on antiaggregant or no antithrombotic therapy, irrespective of age. Thus, D-dimers appear to be a useful parameter for assessing the degree of hypercoagulability of patients whatever their age.

[Diagnostic value of D-dimer in patients with a low pretest probability of deep venous thrombosis of lower extremities]

BACKGROUND

We aimed to assess the accuracy of a diagnostic strategy including broth clinical assessment and determination of D-dimer (DD) in patients with clinically suspicion of low pretest probability of deep venous thrombosis (DVT).

METHOD

149 outpatients (mean age 69; SD 16) with clinically suspected proximal DVT attending our Emergency Department and classified as low pretest probability were included in an observational prospective study. In patients with a DD (STA Liatest D-Di, Diagnostica Stago, Asnières sur Seine, France) concentration below the cut-off value (0.4 ng/ml) the diagnosis of DVT was readily ruled out, whereas those individuals with a positive DD result underwent compression Doppler venous ultrasound. A 3-month clinical follow-up was carried out in those patients in whom a diagnosis of DVT was initially excluded.

RESULTS

Only 2 cases of DVT were confirmed (prevalence 1.3%; CI 95%, 0.2-5.3). In 47.6% of cases, a DD negativity ruled out the diagnosis of DVT. The rate of negative DD results was significantly lower in patients below 70 years of age as compared to older patients (73.6 versus 33.3%) (p < 0.001). Sensitivity, specificity, positive predictive value and negative predictive value of DD in our series were 100% (CI 95%,19.7-95.1), 48.3% (CI 95%, 40.0-56.7), 2.6% (CI 95%, 0.4-9.8) and 100% (CI 95%, 93.6-99.8) respectively, the latter being similar in the two age groups. No case of DVT was diagnosed during the follow-up period.

CONCLUSIONS

In patients with a low pretest probability of DVT a negative DD result reliably and safely rules out such diagnosis. However, the diagnostic value of DD is lower in elderly patients (>= 70 years of age) due to a lower rate of negative results in these individuals.

D-dimer testing: the role of the clinical laboratory in the diagnosis of pulmonary embolism

Pulmonary embolism is a common, yet often unsuspected and unrecognised disease associated with a high mortality. New, objective, "user friendly" and cost effective diagnostic strategies are being explored. D-dimers, the fibrinolytic degradation products of crosslinked fibrin, have emerged as the most useful of the procoagulant activity and ongoing fibrinolysis markers. D-dimer measurements are very sensitive in excluding a diagnosis of pulmonary embolism in the setting of normal values, a low clinical suspicion, and non-diagnostic lung scans. Several assays have been developed and are reviewed.

Results of a new rapid d-dimer assay (cardiac d-dimer) in the diagnosis of deep vein thrombosis

The objective was to evaluate the accuracy of a new full blood rapid D-dimer assay in the diagnosis of suspected deep vein thrombosis (DVT). In 100 consecutive patients with suspected DVT, clinical probability was staged according to a pretest score proposed by Wells. For the determination of plasma D-dimer, heparin and citrate blood samples were drawn, and Cardiac D-dimer, STA-LIA, and Tina-quant tests were performed. Final diagnosis was confirmed either by duplex sonography or ascending venography. DVT was diagnosed in 37%, thrombophlebitis in 10%, and no venous thromboembolism was diagnosed in 52%. In 2% pulmonary embolism was detected and one patient was dismissed before final diagnosis. Cardiac D-dimer assay from citrate tubes showed a sensitivity of 88.6%, a specificity of 54%, a positive predictive value of 57.4%, and a negative predictive value of 87.1%. Nearly identical results were observed with heparin tubes. Corresponding results were 88.6%, 48%, 52.5%, and 85.7% for STA-LIA and 88.6%, 46%, 53.4%, and 85.2% for Tina-quant, respectively. In conclusion, we can say that Cardiac D-dimer is a rapid, whole blood assay with a great potential for clinical use. It can help in diagnosing DVT from citrate as well as heparin tubes with comparable sensitivity, specificity, positive and negative predictive values as STA-LIA and Tina-quant tests.

Markers of plasma coagulation and fibrinolysis after acute deep venous thrombosis

OBJECTIVE

Plasma markers of coagulation and fibrinolysis have proved sensitive in the initial diagnosis of acute deep venous thrombosis (DVT). The purpose of this study was to examine the evolution and utility of measuring D-dimer and prothrombin fragment 1+2 (F 1+2) levels after an acute DVT.

METHODS

Subjects with DVT confirmed by ultrasonography had quantitative plasma D-dimer and F 1+2 levels determined before anticoagulation. Ultrasound scan and coagulation studies were repeated at 3, 7, and 14 days; 1 month; and every 3 months for 1 year.

RESULTS

Sixty-one patients with a median initial thrombus score of 3 (interquartile range, 2-7) were followed up for 266 days (interquartile range, 91.5-364 days). Initial D-dimer levels were elevated in 92.7% of patients and were associated with thrombus extent (P =.003), whereas F 1+2 levels were increased in 94.5% of patients and were lower in patients with isolated calf vein thrombosis (P =.001). Initial D-dimer (P =.002) and F 1+2 levels (P =.009) were significantly higher in the 26 (43%) patients with recurrent thrombosis during follow-up. Initial D-dimer levels of 2000 ng/mL or greater were predictive of recurrent events after both proximal and isolated calf vein thrombosis. Although interval increases in these markers had little value in detecting recurrent thrombotic events, D-dimer levels of 1000 ng/mL or greater and 500 ng/mL or greater had respective sensitivities of 89.3% and 100% in detecting early and late recurrences. Corresponding specificities were 35.6% and 53.9%.

CONCLUSIONS

Initial D-dimer levels are determined by total thrombus load and remain elevated long after an acute DVT. F 1+2 levels are less sensitive to thrombus score and return to baseline more quickly. Initial levels of these markers may have some utility in predicting the risk of ultrasound scan-documented recurrences, whereas increased D-dimer levels are a sensitive but nonspecific marker of these events.

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.