Widely Used Types and Clinical Applications of D-Dimer Assay

Bilateral massive bloody pleural effusions as a rare presentation of ovarian hyperstimulation syndrome: A case report and literature review

OBJECTIVE

Pulmonary complications related to ovarian hyperstimulation syndrome (OHSS) can occur following assisted reproductive technologies (ART). However, bloody pleural effusions are exceedingly rare. We present a case of a patient who underwent ART treatment and developed OHSS, subsequently experiencing bilateral massive bloody pleural effusion.

CASE REPORT

A 32-year-old woman with primary infertility underwent in vitro fertilization (IVF) treatment. After oocyte retrieval, she presented to the emergency department with a chief complaint of abdominal distention and chest pain. Ovarian hyperstimulation syndrome, complicated by bilateral massive bloody pleural effusion (exudative), was diagnosed. Her d-dimer was initially elevated, then decreased gradually, and her shortness of breath improved. The patient was discharged without any clinical sequelae.

CONCLUSION

OHSS can lead to life-threatening complications such as pleural effusion and, in rare cases, bloody pleural effusion. Following oocyte retrieval, an elevated d-dimer level has no specific diagnostic role and should only be used to rule out thromboembolic events.

The role of D-dimer changes in predicting delivery time in preterm premature rupture of membranes: a retrospective analysis

INTRODUCTION

Pregnancy induces a hypercoagulable state, characterized by increased coagulation factors and decreased anticoagulants, alongside ongoing fibrinolysis marked by elevated D-dimer (DD) levels. Reference values for DD in pregnancy often exceed the non-pregnant cutoff due to these changes. Elevated DD levels are common in late pregnancy and may correlate with complications such as gestational diabetes, hypertension, and preterm delivery, particularly in cases of preterm premature rupture of membranes (PPROM). This study investigates the association between DD levels, the duration from PPROM diagnosis to delivery, and neonatal outcomes.

METHODS

This retrospective study was conducted at the Department of Perinatology, Etlik City Hospital, Ankara, Turkey, from October 2022 to May 2023. Eighty patients with PPROM between 24 and 36 weeks of gestation were included. Routine blood tests and coagulation parameters, including DD, were monitored every other day for 2 weeks. Patients were classified into two subgroups based on whether labor occurred within 7 days of PPROM diagnosis. Statistical analyses included the Mann-Whitney U test, Student's t test, Chi-square test, Friedman test, Durbin-Conover test, generalized estimating equations (GEE), and ROC analysis.

RESULTS

Gestational age at admission was significantly lower in patients who delivered later than 7 days post-PPROM. Significant differences were observed in ultrasonographic measurements, with larger fetal parameters in the early delivery group. Higher DD levels at the third follow-up correlated with shorter durations to delivery (p = 0.021). Longitudinal analysis showed significant fluctuations in DD levels over time, particularly near delivery. The GEE analysis demonstrated a strong inverse relationship between DD levels and time to delivery (p = 0.004), supported by ROC analysis (AUROC = 0.811).

CONCLUSIONS

Elevated DD levels are associated with shorter durations from PPROM diagnosis to delivery, indicating their potential utility in predicting labor onset. Monitoring DD levels may help in clinical decision-making for managing PPROM, including planning neonatal care and timing of interventions.

Identification of fibrinogen as a plasma protein binding partner for lecanemab biosimilar IgG

OBJECTIVE

Recombinant monoclonal therapeutic antibodies like lecanemab, which target amyloid beta in Alzheimer's disease, offer a promising approach for modifying the disease progression. Due to its relatively short half-life, lecanemab administered as a bi-monthly infusion (typically 10 mg/kg) has a relatively brief half-life. Interaction with abundant plasma proteins binder in the bloodstream can affect pharmacokinetics of drugs, including their half-life. In this study, we investigated potential plasma protein binding (PPB) interaction to lecanemab using lecanemab biosimilar.

METHODS

Lecanemab biosimilar used in this study was based on publicly available sequences. ELISA and western blotting were used to assess lecanemab biosimilar immunoreactivity in the fractions of human plasma obtained through size exclusion chromatography. The binding of lecanemab biosimilar to candidate plasma binders was confirmed by western blotting, ELISA, and surface plasmon resonance analysis.

RESULTS

Using a combination of equilibrium dialysis, ELISA, and western blotting in human plasma, we first describe the presence of likely PPB partners to lecanemab biosimilar and then identify fibrinogen as one of them. Utilizing surface plasmon resonance, we confirmed that lecanemab biosimilar does bind to fibrinogen, although with lower affinity than to monomeric amyloid beta.

INTERPRETATION

In the context of lecanemab therapy, these results imply that fibrinogen levels could impact the levels of free antibodies in the bloodstream and that fibrinogen might serve as a reservoir for lecanemab. More broadly, these results indicate that PPB may be an important consideration when clinically utilizing therapeutic antibodies in neurodegenerative disease.

International Council for Standardization in Haematology Guidance for New Lot Verification of Coagulation Reagents, Calibrators, and Controls

The clinical laboratory uses commercial products with limited shelf life or certain expiry dates requiring frequent lot changes. Prior to implementation for clinical use, laboratories should determine the performance of the new reagent lot to ensure that there is no significant shift in reagent performance or reporting of patient data. This guideline has been written on behalf of the International Council for Standardization in Haematology (ICSH) to provide the framework and provisional guidance for clinical laboratories for evaluating and verifying the performance of new lot reagents used for coagulation testing. These ICSH Working Party consensus recommendations are based on good laboratory practice, regulatory recommendations, evidence emerged from scientific publications, and expert opinion and are meant to supplement regional standards, regulations, or requirements.

D-dimers in advanced liver cirrhosis: Useful biomarker or not?

In clinical practice, the d-dimer levels rule out venous thromboembolism and diagnose disseminated intravascular coagulation. d-dimers increase in both physiological and pathological conditions. Liver cirrhosis, especially in the final stages, is characterized by complex coagulation and fibrinolysis factor disorders. Multiple mechanisms tried to explain the increased d-dimer levels in patients with liver cirrhosis and ascites. The d-dimer cut-off level used to rule out venous thromboembolism in cirrhosis is higher than that used to confirm the diagnosis of VTE or DIC in noncirrhotic patients. The cut-off d-dimer level used for the prognosis of thrombotic events is not standardized in advanced liver cirrhosis. Thus, it is necessary to update the clinical guidelines regarding the usefulness of d-dimer testing in advanced liver cirrhosis and the cut-off d-dimer levels, which should vary based on the detection method.

Exploring the Prognostic Role of D-dimer Levels in Pancreatic Cancer: A Comprehensive Review of Clinicopathological Associations

Pancreatic cancer is known for its dismal prognosis and high mortality rate, primarily due to late-stage diagnosis and aggressive disease progression. Finding reliable prognostic biomarkers is crucial in improving patient outcomes and guiding treatment strategies. D-dimer, a fibrin degradation product, has emerged as a potential biomarker of interest in various cancers due to its association with coagulation abnormalities. This comprehensive review investigates the prognostic role of D-dimer levels in pancreatic cancer by synthesizing current research and exploring its clinicopathological associations. Elevated D-dimer levels in pancreatic cancer patients have been linked to poorer clinical outcomes, including reduced overall survival and increased disease progression. The review examines how D-dimer levels correlate with tumor characteristics such as stage, grade, and metastatic spread, highlighting its potential utility as a prognostic marker. Additionally, the review addresses the methodological challenges in D-dimer measurement and the need for standardized protocols to enhance the reliability and applicability of results. Future research directions are identified, focusing on validating D-dimer's clinical utility and integrating it into routine practice for risk stratification and personalized treatment planning. By providing a comprehensive overview of D-dimer's prognostic value, this review aims to contribute to developing more effective management strategies for pancreatic cancer, ultimately improving patient care and outcomes.

The performance of quantitative D-dimer assays in Chinese clinical laboratories by analyzing data from National External quality Assessment Scheme

BACKGROUND AND AIMS

To investigate performance of D-dimer assays in China and address analytical quality issues.

MATERIALS AND METHODS

D-dimer assays data were collected from China National External Quality Assessment Scheme (China NEQAS) from 2014 to 2022. We analyzed reagents, assay results, reporting unit and cutoffs in 2022 China NEQAS. Interlaboratory coefficient variations (CVs) and influence of modified/unmodified test systems on CVs were investigated over 9 years.

RESULTS

There were 82 reagent brands in China NEQAS, but 55 reagent instructions did not indicate expression unit (DDU or FEU). Up to 7-fold of the ratio of max-to-min mean results was shown among different assays with same unit on the same sample. A prevalence of FEU (63.4%) over DDU (17.1%) was observed. Although 669 laboratories (37.9%) among 1766 laboratories used reagents without VTE exclusion claim, they also reported cutoffs. The CVs of only two assays were decreasing over years. CVs of modified test systems were higher than those of unmodified systems before improvement.

CONCLUSIONS

Expression unit should be required to label in package inserts by regulatory authority. Laboratory professionals should follow instructions for use and prefer unmodified test systems for clinical safely application. Harmonization of reporting units through collaborative efforts is the promising step.

Chest non‑contrasted computed tomography in detecting acute pulmonary thromboembolism: A single‑center retrospective study

The object of the study was to evaluate comprehensively the value of chest non-contrasted CT (NC-CT) in detecting acute pulmonary thromboembolism (APE). All patients were categorized into two groups: i) With APE; and ii) without APE based on clinical diagnosis. Using the clot distribution on computed tomography pulmonary angiography (CTPA), APE was divided into central and peripheral APE. Imaging features including hyperdense lumen sign and peripheral wedge-shaped opacity on chest NC-CT were evaluated. The attenuation value of peripheral wedge-shaped opacity on NC-CT was compared between patients with and without APE. Among the 273 patients, there were 110 patients with APE, 49 patients with central APE and 61 patients with peripheral APE and 163 patients without APE. The hyperdense lumen sign had a sensitivity of 30.0% and a specificity of 97.6% in detecting APE. The sensitivity and specificity of hyperdense lumen sign in detecting central APE were 57.1 and 97.6%, respectively, while the relevant percentages in detecting peripheral APE were 8.2 and 97.6%, respectively. The mean attenuation value of peripheral wedge-shaped opacity in patients with APE was significantly lower than that in patients without APE (P<0.001). Regarding the age-adjusted D-dimer, there was a decrease of eight D-dimer positive cases for patients >50 years old without APE, confirmed by CTPA. In conclusion, chest NC-CT cannot be used as an alternative modality for CTPA in diagnosing APE, however, the hyperdense lumen sign had high specificity in the diagnosis of central APE. Patients with this symptom and increased D-dimer may not require further CTPA. The lower attenuation value of peripheral wedge-shaped opacity on NC-CT suggested APE, and CTPA confirmation was required. The age-adjusted D-dimer had higher specificity in excluding APE.

Finding the Optimal Screening Test for Periprosthetic Joint Infection: A Prospective Study

BACKGROUND

No single test has demonstrated absolute accuracy in the diagnosis of periprosthetic joint infection (PJI). Serological markers are often used as screening tools to avoid unnecessary joint aspiration in cases with a low probability of infection. This study aimed to determine the utility of standard-of-care serological tests as a screening tool for PJI in patients undergoing revision arthroplasty.

METHODS

This prospective study enrolled 502 patients undergoing revision hip or knee arthroplasty between May 2017 and August 2021. A PJI was defined using a modified definition of the 2018 International Consensus Meeting criteria. Plasma D-dimer, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen were measured preoperatively. There were 82 patients undergoing reimplantation who were excluded. Additionally, 8 patients who had an inconclusive International Consensus Meeting score were also excluded. Of the 412 included patients, 317 (76.9%) underwent revision for aseptic failure, and 95 (23.1%) had PJI. Receiver operating characteristic curves were used to assess the diagnostic utility of each serological test. A pairwise comparison with Bonferroni correction was performed to determine whether the differences in areas under the curve (AUCs) between the tests were significant. Additional analyses were performed to find the threshold for each test that offered 100% sensitivity, allowing it to be the optimal screening test.

RESULTS

All 4 serological markers, D-dimer (AUC 0.860, sensitivity 81.3%, specificity 81.7%), CRP (AUC 0.862, sensitivity 90.4%, specificity 70.0%), ESR (AUC 0.833, sensitivity 73.9%, specificity 85.2%), and fibrinogen (AUC 0.798, sensitivity 74.7%, specificity 75.4%), demonstrated comparable accuracy for the diagnosis of PJI (all P > .05). When maximizing sensitivity to 100%, D-dimer demonstrated the highest specificity (AUC 0.860, specificity 40.2%), outperforming ESR (AUC 0.833, specificity 3.3%), fibrinogen (AUC 0.798, specificity 2.3%), and CRP (AUC 0.862, specificity 0%). A plasma D-dimer level of ≥ 244 ng/mL was identified as the optimal cutoff for use as a screening test.

CONCLUSIONS

Although plasma D-dimer demonstrated similar diagnostic accuracy as CRP, ESR, and fibrinogen, it outperformed all 3 aforementioned serological markers when used as a screening test for PJI.

LEVEL OF EVIDENCE

Level II.

Advances in D-dimer testing: progress in harmonization of clinical assays and innovative detection methods

The D-dimer is a sensitive indicator of coagulation and fibrinolysis activation, especially valuable as a biomarker of intravascular thrombosis. Measurement of plasma D-dimer levels plays a crucial role in the diagnosis and monitoring of conditions such as deep vein thrombosis, pulmonary embolism, and disseminated intravascular coagulation. A variety of immunoassays, including enzyme-linked immunosorbent assays, latex-enhanced immunoturbidimetric assays, whole-blood aggregation analysis, and immunochromatography assays, are widely used in clinical settings to determine D-dimer levels. However, the results obtained from different D-dimer assays vary significantly. These assays exhibit intra-method coefficients of variation ranging from 6.4% to 17.7%, and the measurement discrepancies among different assays can be as high as 20-fold. The accuracy and reliability of D-dimer testing cannot be guaranteed due to the lack of an internationally endorsed reference measurement system (including reference materials and reference measurement procedures), which may lead to misdiagnosis and underdiagnosis, limiting its full clinical application. In this review, we present an in-depth analysis of clinical D-dimer testing, summarizing the existing challenges, the current state of metrology, and progress towards harmonization. We also review the latest advancements in D-dimer detection techniques, which include mass spectrometry and electrochemical and optical immunoassays. By comparing the basic principles, the definition of the measurand, and analytical performance of these methods, we provide an outlook on the potential improvements in D-dimer clinical testing.

Absolute protein quantification based on calibrated particle counting using electrospray-differential mobility analysis

The traceability of in vitro diagnostics or drug products is based on the accurate quantification of proteins. In this study, we developed an absolute quantification approach for proteins. This method is based on calibrated particle counting using electrospray-differential mobility analysis (ES-DMA) coupled with a condensation particle counter (CPC). The absolute concentration of proteins was quantified with the observed protein particle number measured with ES-DMA-CPC, and the detection efficiency was determined by calibrators. The measurement performance and quantitative level were verified using two certificated reference materials, BSA and NIMCmAb. The linear regression fit for the detection efficiency values of three reference materials and one highly purified protein (myoglobin, BSA, NIMCmAb and fibrinogen) indicated that the detection efficiency and the particle size distribution of these proteins exhibited a linear relationship. Moreover, to explore the suitability of the detection efficiency-particle size curve for protein quantification, the concentrations of three typical proteinaceous particles, including two high molecular weight proteins (NIST reference material 8671 and D-dimer) and one protein complex (glutathione S-transferase dimer), were determined. This work suggests that this calibrated particle counting method is an efficient approach for nondestructive, rapid and accurate quantification of proteins, especially for measuring proteinaceous particles with tremendous size and without reference standards.

Identification of Fibrinogen as a Plasma Protein Binding Partner for Lecanemab Biosimilar IgG: Implications for Alzheimer's Disease Therapy

OBJECTIVE

Recombinant monoclonal therapeutic antibodies like lecanemab, which target amyloid beta in Alzheimer's disease, offer a promising approach for modifying the disease progression. Due to its relatively short half-life, Lecanemab, administered as a bi-monthly infusion (typically 10mg/kg) has a relatively brief half-life. Interaction with abundant plasma proteins binder in the bloodstream can affect pharmacokinetics of drugs, including their half-life. In this study we investigated potential plasma protein binding interaction to lecanemab using lecanemab biosimilar.

METHODS

Lecanemab biosimilar used in this study was based on publicly available sequences. ELISA and Western blotting were used to assess lecanemab biosimilar immunoreactivity in the fractions human plasma sample obtained through size exclusion chromatography. The binding of lecanemab biosimilar to candidate binders was confirmed by Western blotting, ELISA, and surface plasmon resonance analysis.

RESULTS

Using a combination of equilibrium dialysis, ELISA, and Western blotting in human plasma, we first describe the presence of likely plasma protein binding partner to lecanemab biosimilar, and then identify fibrinogen as one of them. Utilizing surface plasmon resonance, we confirmed that lecanemab biosimilar does bind to fibrinogen, although with lower affinity than to monomeric amyloid beta.

CONCLUSION

In the context of lecanemab therapy, these results imply that fibrinogen levels could impact the levels of free antibodies in the bloodstream and that fibrinogen might serve as a reservoir for lecanemab. More broadly, these results indicate that plasma protein binding may be an important consideration when clinically utilizing therapeutic antibodies in neurodegenerative disease.

A new surface plasmon resonance-based immunoassay for rapid and sensitive quantification of D-dimer in human plasma for thrombus screening

D-dimer is a protein fragment generated during the fibrin breakdown by plasmin, and it serves as a mature biomarker for diagnosing thrombotic disorders. A novel immunoassay method based on surface plasmon resonance (SPR) has been developed, validated, and successfully applied for the quantification of D-dimer in human plasma with high sensitivity and rapidity. In this methodological study, we investigated the activity and stability of the SPR biosensor, sample pre-processing, washing conditions, intra-day and inter-day precision and accuracy and detection parameters, including a limit of detection of 8.3 ng/mL, a detection range spanning from 31.25 to 4000 ng/mL, and a detection time of 20 min. We compared D-dimer plasma concentration determination results using SPR with a classical latex-enhanced immunoturbidimetric immunoassay in 29 healthy individuals and thrombotic patients, and both methods exhibited consistency. Furthermore, we propose a hypothesis about the relationship between the concentration of D-dimer and its molecular weight. With an increase in the D-dimer concentration in plasma, the D-dimer approaches its simplest form (190 kDa).

Unified calibration of D-dimer can improve the uniformity of different detection systems

Background

D-dimer at a low level is important evidence for excluding the onset and progression of thrombosis. It is readily detectable and yields rapid results, although significant variability exists among different detection systems. Our study aims to enhance the consistency across various detection systems.

Methods

Twelve detection systems were included in our study. We sought to address this inconsistency by using various calibrators (two supplied by manufacturers and two comprising pooled human plasma diluted with different diluents) to standardize D-dimer measurements. We categorized the data into three groups according to D-dimer concentration levels: low (≤0.5 mg/L), medium (>0.5 mg/L - <3 mg/L), and high (≥3 mg/L). We then analyzed the data focusing on range, consistency, comparability, negative coincidence rate, and false negative rate.

Results

Calibrating with pooled human plasma led to narrower result ranges in the low and medium groups (P < 0.05). In the low group, consistency improved from weak to strong (ICC 0.4-0.7, P﹤0.05), while it remained excellent in the other groups and overall (ICC﹥0.75, P﹤0.05). The percentage of pairwise comparability increased in both the low and high groups. Additionally, there was an increase in the negative coincidence rate.

Conclusion

These findings demonstrate that uniform calibration of D-dimer can significantly enhance the consistency of results across different detection systems.

Post-operative venous thromboembolism in patients after extracranial otologic surgery: A case series

Objective

This study aimed to report 9 venous thromboembolism (VTE) cases after extracranial otologic surgery and analyze the potential risk factors.

Study design

Case series.

Setting

Single tertiary-level academic center.

Methods

Totally, 9 cases of VTE were identified among adults who underwent extracranial otologic surgery at our hospital from January 2018 to December 2020. Caprini risk scores were calculated, and comprehensive preoperative, operative, and postoperative clinical data within 14 days were collected to assess the evidence of VTE.

Results

The median age of 9 patients was 64 years old. Among them, 7 (77.8%) patients presented with intramuscular vein thrombosis, 1 (11.1%) patient had deep vein thrombosis, and 1 (11.1%) patient experienced pulmonary embolism. Preoperatively, 8 (88.9%) patients had low or middle Caprini risk scores (≤4) with an average of 2.67 ± 0.47 points. The average Caprini scores for all patients were 4.44 ± 0.35 on postoperative day (POD)1 and 5.67 ± 0.64 on POD14. D-dimer levels were collected, indicating an average of 0.55 ± 0.17 mg/FEU preoperatively, 8.53 ± 3.94 mg/FEU at day 1, and 3.76 ± 0.45 mg/FEU at POD14. In postoperative period, 7 (77.8%) patients experienced vertigo/dizziness and/or head immobility/bed rest.

Conclusion

The present study highlighted that patients with low- and middle-risk of VTE undergoing otologic surgery should be also vigilant about postoperative VTE. Vertigo/dizziness and/or head immobility/bed rest in postoperative period should be considered as minor risk factors for developing VTE in patients undergoing extracranial otologic surgery. Conducting perioperative assessments, including Caprini risk score evaluation, D-dimer testing, and venous ultrasound of lower extremities, is recommended to ensure patients' safety.

Management of Deep Vein Thrombosis: An Update Based on the Revised AWMF S2k Guideline

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are the most common manifestations of venous thromboembolism (VTE). Most DVTs affect the lower-extremity veins. Since the symptoms of DVT are non-specific, a prompt and standardised diagnostic work-up is essential to minimise the risk of PE in the acute phase and to prevent thrombosis progression, post-thrombotic syndrome and VTE recurrence in the long-term. Only recently, the AWMF S2k guidelines on Diagnostics and Therapy of Venous Thrombosis and Pulmonary Embolism have been revised. In the present article, we summarize current evidence and guideline recommendations focusing on lower-extremity DVT (LEDVT). Depending on whether the diagnostic work-up is performed by a specialist in vascular medicine or by a primary care physician, different diagnostic algorithms are presented that combine clinical probability, D-dimer testing and diagnostic imaging. The diagnosis of ipsilateral recurrent DVT poses a particular challenge and is presented in a separate algorithm. Anticoagulant therapy is an essential part of therapy, with current guidelines clearly favouring regimens based on direct oral anticoagulants over the traditional sequential therapy of parenteral anticoagulants and vitamin K antagonists. For most DVTs, a duration of therapeutic-dose anticoagulation of at least 3 to 6 months is considered sufficient, and this raises the question of the risk of VTE recurrence after discontinuation of anticoagulation and the need for secondary prophylaxis in the long-term. Depending on the circumstances and trigger factors that have contributed to the occurrence of DVT, management strategies are presented that allow decision-making taking into account the individual bleeding risk and patient's preferences.

Diagnostic performance of plasma D-dimer, fibrinogen, and D-dimer to fibrinogen ratio as potential biomarkers to predict hypertension-associated acute ischemic stroke

Background

Ischemic stroke is a common type of stroke that leads to death and functional disability in hypertensive patients. However, there are no well-studied non-invasive and less expensive fluid biomarkers routinely used to detect ischemic stroke in hypertensive patients. Hence, this study aimed to tease out the performance of D-dimer, fibrinogen, and the D-dimer to fibrinogen ratio (DDFR) in predicting hypertension-associated acute ischemic stroke.

Methods

A hospital-based cross-sectional study was done from October 2022 to January 2022 at Yikatit 12 Hospital Medical College, Ethiopia. We recruited 55 hypertensive patients who had an ischemic stroke and 110 who did not. A ROC curve was used to calculate the areas under the curves (AUCs) and determine the diagnostic power of the D-dimer, fibrinogen, and DDFR. The Youden index was used to find the best cut-off points for biomarkers in detecting acute ischemic stroke. A De Long test was employed to show whether there was a significant difference between the AUCs of biomarkers in diagnosing ischemic stroke.

Results

D-dimer yielded the highest diagnostic power (AUC = 0.776) in detecting acute ischemic stroke, followed by DDFR (AUC = 0.763) and fibrinogen (AUC = 0.694), but there was no significant difference between them. At 0.52 μg/ml cut-off point, D-dimer had 82.9% sensitivity, 66.7% specificity, 62.5% PPV, and 85.3% NPV to diagnose acute ischemic stroke. Fibrinogen could detect acute ischemic stroke at 405.85 mg/dl level, with 70.0% sensitivity, 57.1% specificity, 41.2% PPV and 81.6% NPV. At a 1.83 ratio, DDFR might also identify ischemic stroke with 80.0% sensitivity, 67.1% specificity, 51.1% PPV, and 88.7% NPV.

Conclusion

We showed D-dimer, fibrinogen, and DDFR as promising, affordable, and non-invasive biomarkers for the detection of ischemic stroke among subjects with hypertension. This will help clinicians make an early diagnosis and better guide patient therapy.

Venous Thromboembolism: Review of Clinical Challenges, Biology, Assessment, Treatment, and Modeling

Venous thromboembolism (VTE) is a massive clinical challenge, annually affecting millions of patients globally. VTE is a particularly consequential pathology, as incidence is correlated with extremely common risk factors, and a large cohort of patients experience recurrent VTE after initial intervention. Altered hemodynamics, hypercoagulability, and damaged vascular tissue cause deep-vein thrombosis and pulmonary embolism, the two permutations of VTE. Venous valves have been identified as likely locations for initial blood clot formation, but the exact pathway by which thrombosis occurs in this environment is not entirely clear. Several risk factors are known to increase the likelihood of VTE, particularly those that increase inflammation and coagulability, increase venous resistance, and damage the endothelial lining. While these risk factors are useful as predictive tools, VTE diagnosis prior to presentation of outward symptoms is difficult, chiefly due to challenges in successfully imaging deep-vein thrombi. Clinically, VTE can be managed by anticoagulants or mechanical intervention. Recently, direct oral anticoagulants and catheter-directed thrombolysis have emerged as leading tools in resolution of venous thrombosis. While a satisfactory VTE model has yet to be developed, recent strides have been made in advancing in silico models of venous hemodynamics, hemorheology, fluid-structure interaction, and clot growth. These models are often guided by imaging-informed boundary conditions or inspired by benchtop animal models. These gaps in knowledge are critical targets to address necessary improvements in prediction and diagnosis, clinical management, and VTE experimental and computational models.

Fast screening using attenuated total reflectance- fourier transform infrared (ATR-FTIR) spectroscopy of patients based on D-dimer threshold value

Attenuated Total Reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy is an emerging technology in the medical field. Blood D-dimer was initially studied as a marker of the activation of coagulation and fibrinolysis. It is mainly used as a potential diagnosis screening test for pulmonary embolism or deep vein thrombosis but was recently associated with COVID-19 severity. This study aimed to evaluate the use of ATR-FTIR spectroscopy with machine learning to classify plasma D-dimer concentrations. The plasma ATR-FTIR spectra from 100 patients were studied through principal component analysis (PCA) and two supervised approaches: genetic algorithm with linear discriminant analysis (GA-LDA) and partial least squares with linear discriminant (PLS-DA). The spectra were truncated to the fingerprint region (1800-1000 cm-1). The GA-LDA method effectively classified patients according to D-dimer cutoff (≤0.5 μg/mL and >0.5 μg/mL) with 87.5 % specificity and 100 % sensitivity on the training set, and 85.7 % specificity, and 95.6 % sensitivity on the test set. Thus, we demonstrate that ATR-FTIR spectroscopy might be an important additional tool for classifying patients according to D-dimer values. ATR-FTIR spectral analyses associated with clinical evidence can contribute to a faster and more accurate medical diagnosis, reduce patient morbidity, and save resources and demand for professionals.

Are the latest point-of-care D-dimer devices ready for use in general practice? A prospective clinical evaluation of five test systems with a capillary blood feature for suspected venous thromboembolism

INTRODUCTION

We evaluated clinical performance of five novel point-of-care (POC) D-dimer devices with a capillary finger stick feature for predicting venous thromboembolism (VTE) in general practice: Exdia TRF Plus (E), AFIAS-1® (A), Standard F200® (S), LumiraDx™ (L) and Hipro AFS/1® (H).

MATERIALS AND METHODS

Primary care patients with a low suspicion of a VTE were asked to consent to (i) draw additional venous blood samples, (ii) perform a capillary POC D-dimer test, (iii) approach their general practitioner afterwards for clinical outcomes. Venous plasma samples were processed on all POC devices and a laboratory-based assay (STA-Liatest®D-Di PLUS assay). Results were compared with clinical outcomes to generate performance characteristics. Capillary and venous blood results were used for a matrix comparison.

RESULTS

Venous plasma samples from 511 participants, of whom 57 had VTE, were used for clinical performance analyses. Areas under Receiving Operating Characteristic Curves ranged from 0.90 (95 % CI: 0.86-0.94) (H) to 0.93 (0.90-0.96) (E). All false-negative rates were below 1.4 % (95 % CI: 0.5 %-3.4 %). Matrix comparison demonstrated correlation coefficients ranging from r = 0.11 (95 % CI: -0.15-0.36) (H) to r = 0.94 (0.90-0.97) (A) with concordance percentages ranging from 71.4 % (applying a D-dimer cutoff of 500 ng/mL) (H) to 100 % (applying an age-dependent D-dimer cutoff) (A).

CONCLUSIONS

Clinical performance of the POC D-dimer devices for predicting a VTE in low-risk patients was comparable to that of a laboratory-based assay. However, our results indicate that the finger stick feature of certain devices should be further improved. (NL71809.028.19.).

Reporting age-adjusted D-dimer cut-off values reduces radiology overuse in emergency department patients with suspected deep venous thrombosis

INTRODUCTION

Venous thromboembolism (VTE) is a leading cause of death, associated with substantial morbidity in the absence of treatment. Our aim was, first, to compare the diagnostic performance of D-dimer for the diagnosis of VTE in the emergency department (ED), when reporting conventional cut-off point versus when additionally reporting age-adjusted values. Second, we explored the ordering pattern of Doppler ultrasound (US) and computerized tomographic pulmonary angiogram (CTPA), before and after reporting of the aforementioned age-adjusted cut-off value.

MATERIALS AND METHODS

We conducted a cross-sectional study to compare the diagnostic performance of D-dimer as a screening for VTE when reporting the conventional cut-off value versus when additionally including the age-adjusted metrics, and a quasi-experimental study to explore the ordering of Doppler US and CTPA before the age-specific metrics were shared in the report in ED patients between 50 and 100 years-old with D-dimer ordering.

RESULTS

The cross-sectional study included 392 patients, 25 with VTE. The specificity using an age-adjusted cut-off value was significantly higher (0.51) compared to a single absolute cut-off (0.42), and the negative likelihood ratio was lower as well (0.08 vs. 0.19), but again not statistically significant. In the quasi-experimental study, there was a decrease in the rate of use of both CTPA and Doppler US (P < 0.05).

CONCLUSION

The intervention improved the use of the D-dimer result in the ED and helped improve the request for imaging tests.

Plasma D-Dimer Is a Promising Marker to Guide Timing of Reimplantation: A Prospective Cohort Study

BACKGROUND

Two-stage exchange arthroplasty remains the preferred surgical treatment for chronic periprosthetic joint infection. Currently, there is no single reliable marker to determine the optimal timing for reimplantation. The purpose of this prospective study was to assess the diagnostic utility of plasma D-dimer and other serological markers in predicting successful control of infection following reimplantation.

METHODS

This study enrolled 136 patients undergoing reimplantation arthroplasty between November 2016 and December 2020. Strict inclusion criteria were applied including the need for a two-week "antibiotic holiday" prior to reimplantation. A total of 114 patients were included in the final analysis. Plasma D-dimer, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen were measured preoperatively. Treatment success was defined using the Musculoskeletal Infection Society Outcome-Reporting Tool. Receiver operating characteristic curves were used to assess the prognostic accuracy of each biomarker in predicting failure following reimplantation at a minimum 1-year follow-up.

RESULTS

Treatment failure occurred in 33 patients (28.9%) at a mean follow-up of 3.2 years (range, 1.0 to 5.7). Median plasma D-dimer was significantly higher in the treatment failure group (1,604 versus 631 ng/mL, P < .001), whereas median CRP, ESR, and fibrinogen were not significantly different between the success and failure groups. Plasma D-dimer demonstrated the best diagnostic utility (area under the curve [AUC] 0.724, sensitivity 51.5%, specificity 92.6%), outperforming ESR (AUC 0.565, sensitivity 93.3%, specificity 22.5%), CRP (AUC 0.541, sensitivity 87.5%, specificity 26.3%), and fibrinogen (AUC 0.485, sensitivity 30.4%, specificity 80.0%). Plasma D-dimer level of ≥1,604 ng/mL was identified as the optimal cutoff that predicted failure following reimplantation.

CONCLUSION

Plasma D-dimer was superior to serum ESR, CRP, and fibrinogen in predicting failure after the second stage of a two-stage exchange arthroplasty for periprosthetic joint infection. Based on the findings of this prospective study, plasma D-dimer may be a promising marker in assessing the control of infection in patients undergoing reimplantation surgery.

LEVEL OF EVIDENCE

Level II.

Unveiling the diagnostic enigma of D-dimer testing in cancer patients: Current evidence and areas of application

BACKGROUND

Cancer is a well-known risk factor for venous thromboembolism (VTE). A combined strategy of D-dimer testing and clinical pre-test probability is usually used to exclude VTE. However, its effectiveness is diminished in cancer patients due to reduced specificity, ultimately leading to a decreased clinical utility. This review article seeks to provide a comprehensive summary of how to interpret D-dimer testing in cancer patients.

METHODS

In accordance with PRISMA standards, literature pertaining to the diagnostic and prognostic significance of D-dimer testing in cancer patients was carefully chosen from reputable sources such as PubMed and the Cochrane databases.

RESULTS

D-dimers have not only a diagnostic value in ruling out VTE but can also serve as an aid for rule-in if their values exceed 10-times the upper limit of normal. This threshold allows a diagnosis of VTE in cancer patients with a positive predictive value of more than 80%. Moreover, elevated D-dimers carry important prognostic information and are associated with VTE reoccurrence. A gradual increase in risk for all-cause death suggests that VTE is also an indicator of biologically more aggressive cancer types and advanced cancer stages. Considering the lack of standardization for D-dimer assays, it is essential for clinicians to carefully consider the variations in assay performance and the specific test characteristics of their institution.

CONCLUSIONS

Standardizing D-dimer assays and developing modified pretest probability models specifically for cancer patients, along with adjusted cut-off values for D-dimer testing, could significantly enhance the accuracy and effectiveness of VTE diagnosis in this population.

Incidence and risk factors of isolated calf muscular venous thrombosis after tibial plateau fractures surgery

BACKGROUND

The risks associated with deep vein thrombosis (DVT) have gained significant recognition over time. A prevalent form of distal DVT is isolated calf muscular venous thrombosis (ICMVT). Despite its common clinical occurrence, data on ICMVT subsequent to tibial plateau fracture (TPF) surgery are scarce. This study aimed to examine the epidemiological characteristics and associated risk factors (RFs) of ICMVT following TPF surgery.

METHODS

For this retrospective analysis, we included patients from our hospital, who underwent TPF surgery between March 2017 and March 2021. Patients' electronic medical records were reviewed, including admission details, fracture classification, surgical procedures, and laboratory biomarkers. The HSS (The American Hospital for Special Surgery) and Rasmussen scores were employed to evaluate the clinical effect. A Color Duplex Flow Imager (CDFI) was regularly used to detect pre- and postoperative venous thrombosis in the lower limbs. Finally, uni- and multivariate logistic regression analyses were used to identify independent RFs associated with ICMVT.

RESULTS

Overall, 481 participants were recruited for analysis. Postoperative ICMVT occurred in 47 patients. All ICMVTs occurred on the affected side. Four of the 47 ICMVT patients exhibited sudden postoperative swelling in the affected limb. The HSS and Rasmussen scores in the non-ICMVT cohort (87.6 ± 8.2, 16.0 ± 1.7) were markedly different from the ICMVT cohort (84.8 ± 8.2, 15.5 ± 1.6) (p = 0.014, p = 0.031). This study finally identified five postoperative ICMVT-related RFs, which were age (> 55 years old) (OR 3.06; 95% CI 1.47-6.37; p = 0.003), gender (female) (OR 2.67; 95% CI 1.37-5.22; p = 0.004), surgical duration (> 114 min) (OR 3.14; 95% CI 1.44-6.85; p = 0.004), elevated white blood cell content (OR 2.85; 95% CI 1.47-5.51; p = 0.002), and hyponatremia (OR 2.31; 95% CI 1.04-5.12; p = 0.040).

CONCLUSION

The epidemiological findings of this study may help predict ICMVT risk after surgery thus facilitating the development of individualized clinical assessments and targeted prevention programs.

Biomarkers in pediatric venous thromboembolism: a systematic review of the literature

BACKGROUND

Accurate prediction of the individual risk of venous thromboembolism (VTE) remains suboptimal in children, and biomarkers are currently not used to stratify the risk of VTE in children.

OBJECTIVES

This study aimed to assess which biological or radiological biomarkers may predict VTE or VTE complications in children.

PATIENTS/METHODS

A literature search was performed for peer-reviewed publications (1990-2022). We included studies addressing the use of biomarkers for patients aged 29 days to 18 years to predict VTE or its complications, including but not limited to TE-related death, VTE recurrence, or postthrombotic syndrome. Given the heterogeneity of the study designs, populations, and outcomes, no quantitative data synthesis was performed.

RESULTS

Forty studies were included, totaling 10,987 participants (median age: 4.7 years). Reports were often lacking critical methodological data, including blood collection method (68% of studies) and timepoints, laboratory testing technique (41%), or primary outcome definition (20%). Forty-six individual biomarkers were assessed for VTE prediction (32 studies, 9525 participants), including d-dimers, fibrinogen, platelet count, white blood cell count, and factor VIII. Albumin, C-reactive protein, d-dimers, factor VIII, and thrombin-antithrombin levels showed promising results for VTE prediction. In 9 studies (1606 participants), no biomarker was consistently predictive of postthrombotic syndrome, VTE persistence, or VTE recurrence in children.

CONCLUSIONS

Several candidate biomarkers were promising in the prediction of VTE in children. Still, discrepancies between different studies and the high risk of bias from the current literature prevent their widespread use in the clinical setting. Further prospective research in various pediatric subpopulations is required.

Association between D-dimer and long-term mortality in patients with acute severe hypertension visiting the emergency department

OBJECTIVE

High levels of D-dimer, a marker of thrombotic events, are associated with poor outcomes in patients with various cardiovascular diseases. However, there has been no research on its prognostic implications in acute severe hypertension. This study investigated the association between D-dimer levels and long-term mortality in patients with severe acute hypertension who visited the emergency department.

DESIGN AND METHOD

This observational study included patients with acute severe hypertension who visited the emergency department between 2016 and 2019. Acute severe hypertension was defined as a systolic blood pressure ≥ 180 mmHg or a diastolic blood pressure ≥ 100 mmHg. Among the 10,219 patients, 4,127 who underwent D-dimer assay were analyzed. The patients were categorized into tertiles based on their D-dimer levels at the time of emergency department admission.

RESULTS

Among the 4,127 patients with acute severe hypertension, 3.1% in the first (lowest) tertile, 17.0% in the second tertile, and 43.2% in the third (highest) tertile died within 3 years. After the adjustment for confounding variables, the third tertile of the D-dimer group (hazard ratio, 6.440; 95% confidence interval, 4.628-8.961) and the second tertile of the D-dimer group (hazard ratio, 2.847; 95% confidence interval, 2.037-3.978) had a significantly higher risk of all-cause mortality over 3 years than the first tertile of the D-dimer group.

CONCLUSIONS

D-dimer may be a useful marker for identifying the risk of mortality among patients with acute severe hypertension who visit the emergency department.

The role of D-dimer and fibrinogen testing in catheter-directed thrombolysis with urokinase for deep venous thrombosis

BACKGROUND

During catheter-directed thrombolysis (CDT), D-dimer (D-D) are generated in large quantities and fibrinogen (FIB) is continuously consumed. Reduction of FIB increases the risk of bleeding. However, there are currently few studies on the relationship between D-D and FIB concentrations during CDT.

OBJECTIVES

To evaluate the relationship of D-D and FIB concentrations during CDT with urokinase for deep venous thrombosis (DVT).

METHOD

17 patients with lower limb DVT were enrolled and treated with CDT. The concentrations of plasma D-D and FIB were measured every 8 h during thrombolysis. The degree of thrombolysis was evaluated, the change rules of D-D and FIB concentrations were analyzed, and the change curve graphs were drawn. The "thrombus volume," "thrombolysis time," "thrombolysis ratio," "D-D peak," "D-D rising speed," "FIB falling speed," and "duration of D-D elevation" were calculated in each patient. The mixed model was used to simulate the time change trend of the plasma D-D and FIB concentrations. Pearson method and linear regression were used to analyze the correlation and linear relationship, respectively.

RESULTS

The D-D concentration first increased rapidly and then decreased gradually, and the FIB concentration continued to decrease during thrombolysis. The rate of the decline of FIB varies with the urokinase dose. The thrombus volume is positively correlated with D-D rising speed, duration of D-D elevation, D-D peak, and FIB falling speed; the D-D rising speed is positively correlated with the D-D peak and FIB falling speed; and the D-D peak is positively correlated with the FIB falling speed. The correlation coefficients were all statistically significant (p < 0.05). Efficacy reached level I-II in 76.5% patients. No major bleeding occurred in any of the patients.

CONCLUSION

During CDT with urokinase for DVT, the concentrations of D-D and FIB show specific changes, and there are some specific relationships between each other. Understanding these changes and relationships may be helpful to adjust the thrombolysis time and urokinase dose more rationally.

Plasma D-Dimer Is Noninferior to Serum C-Reactive Protein in the Diagnosis of Periprosthetic Joint Infection

BACKGROUND

No single test has demonstrated absolute accuracy in the diagnosis of periprosthetic joint infection (PJI). Serological markers are often used as screening tools in the workup of patients with suspected PJI. This study aimed to determine the diagnostic utility of plasma D-dimer for PJI in a variety of clinical scenarios.

METHODS

This prospective study enrolled 502 patients undergoing revision hip or knee arthroplasty. PJI was defined per a modified version of the 2018 International Consensus Meeting (ICM) criteria. Plasma D-dimer, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen were measured preoperatively. Receiver operating characteristic curves were used to assess the utility of each biomarker in the diagnosis of PJI. Pairwise comparison with Bonferroni correction was performed to determine whether the differences in areas under the curve (AUCs) between the markers were significant.

RESULTS

Of the 412 patients included, 317 (76.9%) did not have an infection (aseptic group) and 95 (23.1%) had an infection (PJI group). All 4 serological markers, D-dimer (AUC, 0.860; sensitivity, 81.3%; specificity, 81.7%), CRP (AUC, 0.862; sensitivity, 90.4%; specificity, 70.0%), ESR (AUC, 0.833; sensitivity, 73.9%; specificity, 85.2%), and fibrinogen (AUC, 0.798; sensitivity, 74.7%; specificity, 75.4%), demonstrated comparable accuracy for the diagnosis of PJI (all p > 0.05). When examining the performance of the different inflammatory markers in diagnosing infection caused by indolent organisms, D-dimer demonstrated the highest sensitivity at 93.8%.

CONCLUSIONS

We found that plasma D-dimer was noninferior to serum CRP and ESR in the diagnosis of PJI and may be a useful adjunct when screening patients undergoing revision total joint arthroplasty.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

The effect of rivaroxaban on biomarkers in blood and plasma: a review of preclinical and clinical evidence

Rivaroxaban is a direct, oral factor Xa inhibitor that is used for the prevention and treatment of various thromboembolic disorders. Several preclinical and clinical studies have utilized specific molecules as biomarkers to investigate the potential role of rivaroxaban beyond its anticoagulant activity and across a range of biological processes. The aim of this review is to summarize the existing evidence regarding the use of blood-based biomarkers to characterize the effects of rivaroxaban on coagulation and other pathways, including platelet activation, inflammation and endothelial effects. After a literature search using PubMed, almost 100 preclinical and clinical studies were identified that investigated the effects of rivaroxaban using molecular biomarkers. In agreement with the preclinical data, clinical studies reported a trend for reduction in the blood concentrations of D-dimers, thrombin-antithrombin complex and prothrombin fragment 1 + 2 following treatment with rivaroxaban in both healthy individuals and those with various chronic conditions. Preclinical and also some clinical studies have also reported a potential impact of rivaroxaban on the concentrations of platelet activation biomarkers (von Willebrand factor, P-selectin and thrombomodulin), endothelial activation biomarkers (matrix metalloproteinase-9, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) and inflammation biomarkers (interleukin-6, tumor necrosis factor-α and monocyte chemoattractant protein-1). Based on the results of biomarker studies, molecular biomarkers can be used in addition to traditional coagulation assays to increase the understanding of the anticoagulation effects of rivaroxaban. Moreover, there is preliminary evidence to suggest that rivaroxaban may have an impact on the biological pathways of platelet activation, endothelial activation and inflammation; however, owing to paucity of clinical data to investigate the trends reported in preclinical studies, further investigation is required to clarify these observations.

Current Diagnosis and Management of Acute Pulmonary Embolism: A Strategy for General Practitioners in Emergency Department

Pulmonary embolism (PE) is a disease with a relatively good prognosis when diagnosed and treated properly. This review aims to analyse available data and combine them into algorithms that physicians can use in the emergency department for quick decision-making in diagnosing and treating PE. The available data show that PE can be excluded through highly sensitive clinical decision rules, i.e. Pulmonary Embolism Rule-Out Criteria (PERC), Wells criteria, and Revised Geneva criteria, combined with D-dimer assessment. In cases where PE could not be excluded through the mentioned strategies, imaging modalities, such as compression ultrasonography (CUS), computed tomographic pulmonary angiography (CTPA), and planar ventilation/perfusion (V/Q) scan, are indicated for a definite diagnosis. Once a diagnosis has been made, treatment of PE depends on its mortality risk as patients are divided into low-, intermediate-, and high-risk cases. High-risk cases are treated for their hemodynamic instability, given parenteral or oral anticoagulant therapy, and are indicated for reperfusion therapy. Intermediate-risk PE is only given parenteral or oral anticoagulants and reperfusion is indicated when anticoagulants fail. Low-risk cases are given oral anticoagulants and based on the Hestia criteria, patients may be discharged and treated as outpatients.

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.

Heterophilic antibodies leading to falsely positive D-dimer concentration in an adolescent

Background

We present the case of a 15-year-old adolescent with suspected pulmonary embolism and repeatedly elevated D-dimer levels.

Key Clinical Question

We aim to determine the cause for elevated D-dimer levels in a patient without venous thromboembolism.

Clinical Approach

When the D-dimer measurement was repeated with different assays, D-dimer levels were within the normal reference interval. Dilution series with assay diluent or low-affinity antibody blocking reagents either did not or only partially decreased the D-dimer value using the original reagent kit.

Conclusion

Analyses suggested the presence of interfering heterophilic antibodies in patient plasma, a known phenomenon with immunoturbidimetric D-dimer assays, which is rarely described. Prior to drawing this conclusion, the patient underwent extensive diagnostic testing, which led to uncertainty and discomfort for the health care providers, the patient, and their family.

Dímero-D en perros con cáncer relacionado al grado, tipo de tumor y conteo plaquetario

En la actualidad se han detectado varios trastornos clínicos relacionados con alteraciones hemostáticas en pacientes con Cáncer, reportados en humanos y perros. Ante esta realidad se proponen nuevos estudios diagnósticos como el Dímero-D (DD) aplicable a pacientes oncológicos. En Medicina Veterinaria, esta prueba es relativamente nueva y sirve para descartar posibles episodios trombóticos y ayuda al diagnóstico precoz de enfermedades relacionadas con la trombosis. El presente trabajo de investigación tuvo como objetivo medir valores de DD en nanogramos·mililitros-1 (ng·mL-1) en perros con cáncer, en los cuales se hizo un análisis multicéntrico de un total de 40 pacientes (n=40) en dos Hospitales Veterinarios de Quito y Guayaquil, en Ecuador. A los pacientes diagnosticados como oncológicos se les realizó una historia clínica detallada, posteriormente se les tomó una muestra de sangre en un tubo citratado, para después ser enviada al laboratorio donde se aplicaría la técnica de inmunofluorescencia para medir la cantidad de DD a través del equipo V-Check, V200 de Bionote, China, y una muestra en tubo con EDTA para hemograma en un equipo automatizado. Se analizaron además los resultados de las histopatologías, clasificándolos según su tipo y grado de tumor y se correlacionaron con los resultados del DD y conteo plaquetario. Entre los resultados se encontró correlación de DD con el tipo y grado de tumor, como también DD y el conteo de plaquetas; en este estudio, los tumores como hemangiosarcomas de bazo, los carcinomas y adenocarcinomas fueron los más comunes en presentar elevaciones de DD, y al igual que aquellos que presentaron una calificación más alta en la escala de grados histológicos.

D-dimer Testing in Pulmonary Embolism with a Focus on Potential Pitfalls: A Narrative Review

D-dimer is a multifaceted biomarker of concomitant activation of coagulation and fibrinolysis, which is routinely used for ruling out pulmonary embolism (PE) and/or deep vein thrombosis (DVT) combined with a clinical pretest probability assessment. The intended use of the tests depends largely on the assay used, and local guidance should be applied. D-dimer testing may suffer from diagnostic errors occurring throughout the pre-analytical, analytical, and post-analytical phases of the testing process. This review aims to provide an overview of D-dimer testing and its value in diagnosing PE and discusses the variables that may impact the quality of its laboratory assessment.

SARS-CoV-2-Induced Amyloidgenesis: Not One, but Three Hypotheses for Cerebral COVID-19 Outcomes

The main neuropathological feature of Alzheimer's disease (AD) is extracellular amyloid deposition in senile plaques, resulting from an imbalance between the production and clearance of amyloid beta peptides. Amyloid deposition is also found around cerebral blood vessels, termed cerebral amyloid angiopathy (CAA), in 90% of AD cases. Although the relationship between these two amyloid disorders is obvious, this does not make CAA a characteristic of AD, as 40% of the non-demented population presents this derangement. AD is predominantly sporadic; therefore, many factors contribute to its genesis. Herein, the starting point for discussion is the COVID-19 pandemic that we are experiencing and how SARS-CoV-2 may be able to, both directly and indirectly, contribute to CAA, with consequences for the outcome and extent of the disease. We highlight the role of astrocytes and endothelial cells in the process of amyloidgenesis, as well as the role of other amyloidgenic proteins, such as fibrinogen and serum amyloid A protein, in addition to the neuronal amyloid precursor protein. We discuss three independent hypotheses that complement each other to explain the cerebrovascular amyloidgenesis that may underlie long-term COVID-19 and new cases of dementia.

Measurement of D-dimer in cerebrospinal fluid using a luminescent oxygen channeling immunoassay

Background

Measurement of D-dimer in cerebrospinal fluid (CSF) allows insight into coagulation system activation in the central nervous system and can be utilized to monitor intracranial hemorrhage as well as acute phase processes beyond hemostasis in inflammatory and neoplastic diseases. So far, the measurability of D-dimer in low and very low concentrations in CSF was limited in conventional immunoassays. Novel high-sensitivity chemiluminescent immunoassays such as the luminescent oxygen channeling immunoassay (LOCI^®) are getting increasingly available but have not been validated in CSF. The aim of this study was to investigate the accuracy and linearity of the LOCI^® in assessing D-dimer in CSF.

Methods

INNOVANCE LOCI hs D-dimer reagent cartridge was used for the measurement of D-dimer in CSF of patients with different neurological diseases. For the evaluation of linearity, dilution series were performed in a pooled CSF sample with the determination of intra-assay precision (CV, coefficient of variation) in 3 individual samples with 20 replicates. Furthermore, D-dimer concentrations measured by LOCI^® were compared with the respective results of a routinely available clinical latex-enhanced immunoassay (HemosiIL D-Dimer HS 500).

Results

Linear regression analysis of the LOCI^® method revealed a r² of 1.00 (p < 0.001) with a regression coefficient B of 1.012 ± 0.003 (CI: 1.005–1.019, p < 0.001) and an intercept of −1.475 ± 1.309 (CI: −4.493 to 1.543); the median intra-assay CV was 0.69% (range: 0.68–0.75). In total, 185 CSF samples were measured by LOCI^® technology, showing a mean concentration of 204.84 ± 2,214.93 ng/ml. D-dimer concentration between LOCI and latex-enhanced immunoassay differed by a factor of 10.6 ± 13.6 on average with a maximum deviation by a factor of 61.3; the maximum deviation was found at low concentrations.

Conclusion

D-dimer in CSF of patients with neurological disease can be reliably measured by the LOCI^® method with high linearity and accuracy at low concentrations.

Plasma D-dimer levels are correlated with disease severity among hypertensive patients: A comparative cross-sectional study

It has been reported that inappropriate acute thrombus formation is the pathophysiological substrate underlying increased risk and severity of target organ damage in hypertension (HTN). However, the relationship between severity of HTN and D-dimer has not been well characterized. The study was aimed to assess plasma D-dimer level and its correlation with disease severity among hypertensives. A comparative cross-sectional study was conducted at Wuhan Asia Heart Hospital among 100 participants (60 hypertensives and 40 controls). The correlation between variables were determined using correlation coefficients, regression analysis, and also using different parametric and nonparametric tests. We observed higher D-dimer levels among hypertensives compared to the healthy controls (P < .001). The D-dimer levels were found to be increased significantly with the severity of HTN (P < .001). D-dimer was found to have a diagnostic power of 86.9% in differentiating complicated from uncomplicated HTN at 0.83 mg/L cutoff value. This study suggests that D-dimer level was higher among hypertensives than control groups and it was also increasing significantly with the severity of HTN. This suggests that hypercoagulability of fibrin plays a role in the occurrence of thromboembolic complications of hypertensive patients.

A Tale of Two D-Dimers: Comparison of Two Assay Methods to Evaluate Deep Vein Thrombosis or Pulmonary Embolism

BACKGROUND

D-dimer testing rules out deep vein thrombosis (DVT) and pulmonary embolism (PE) in low-risk emergency department (ED) patients. Most research has measured fibrin-equivalent units (FEUs), however, many laboratories measure D-dimer units (DDUs).

OBJECTIVE

Our aim was to determine whether either DDU measurements or FEU measurements can rule out DVT/PE using traditional or age-related cutoff values.

METHODS

We performed a de-identified multicenter retrospective evaluation of D-dimer in nonpregnant adult ED patients to evaluate for DVT/PE. DDUs were multiplied by 2 to determine equivalent FEUs prior to analysis. Sensitivity measurements for D-dimer were calculated for FEUs, DDUs, combined FEU/DDUs, and multiple age-adjusted values.

RESULTS

We identified 47,088 ED patients with a D-dimer laboratory value (27,307 FEUs/19,781 DDUs) and 1623 DVT/PEs. The median combined FEU/DDU D-dimer was 400 ng/mL FEUs (interquartile range [IQR] 300-900 ng/mL FEUs) for patients without a DVT/PE vs 2530 ng/mL FEU (IQR 1094-6000 ng/mL FEUs) with a DVT/PE (p < 0.001), overall sensitivity of 87.3% (95% confidence interval [CI] 87.0-87.6%) and negative predictive value of 99.3% (95% CI 99.2-99.4%). Individually, FEUs performed better than DDUs, with sensitivities of 88.0% (95% CI 85.8-89.9%) and 86.1% (95% CI 83.1-88.7%), respectively; however, this difference was not statistically significant. Combined age-adjusted performance had a sensitivity of 90.3% (95% CI 88.3-92.0%); however, a new DDU-only age-adjusted criteria had the highest sensitivity of 91.1% (95% CI 87.9-93.6%).

CONCLUSIONS

Our undifferentiated D-dimer measurements had a slightly lower sensitivity to rule out DVT/PE than reported previously. Our data support using either DDU or FEU measurements for all ages or when using various age-adjusted criteria to rule out DVT/PE.

Association of D-dimer with short-term risk of venous thromboembolism in acutely ill medical patients: A systematic review and meta-analysis

BACKGROUND

D-dimer, a marker of ongoing procoagulant activity, has been widely used for the diagnosis of venous thromboembolism (VTE). The prognostic significance of D-dimer in stratifying VTE risk for acutely ill medical patients has not been well-established.

METHODS

A literature search was performed to collect studies that compared the incidence of short-term VTE between acutely ill medical patients with elevated or nonelevated D-dimer levels. The cutoff of D-dimer was 0.5 μg/mL or otherwise defined by included studies. The study endpoint was any occurrence of VTE (inclusive of deep vein thrombosis [DVT], pulmonary embolism, or VTE-related death) within 90 days of hospital presentation. A meta-analytic approach was employed to estimate the odds ratio (OR) with 95% CI by fitting random-effects models using the generic inverse variance weighted approach.

RESULTS

A total of 10 studies representing 31,119 acutely ill medical patients were included. Compared to those with nonelevated D-dimer levels, patients with elevated D-dimer had approximately threefold greater odds for short-term VTE within 90 days (OR, 3.28; 95% CI, 2.44 to 4.40; p < 0.0001). The association of elevated D-dimer with VTE composite (OR, 3.33; 95% CI, 2.20 to 5.02) and with DVT (OR, 3.26; 95% CI, 2.32 to 4.58) was comparable. The association was significant among patients who presented various acute medical illness (OR, 2.68; 95% CI, 2.01 to 3.58) and those who presented with acute stroke (OR, 3.25; 95% CI, 2.31 to 4.58).

CONCLUSION

Elevation of D-dimer was predictive of the occurrence of VTE within 90 days among acutely ill medical patients. PROSPERO Registration ID: CRD42021264555.

D-dimer for screening of aortic dissection in patients with ST-elevation myocardial infarction

BACKGROUND

Acute aortic dissection (AAD) with concurrent ST-segment elevation myocardial infarction (STEMI) is relatively rare and sometimes overlooked. As D-dimer testing has been reported to have high sensitivity to diagnose AAD in a clinical scale, Aortic Dissection Detection Risk Score (ADD-RS), a point-of-care D-dimer analyzer capable of measuring in 10 min would be useful to deny AAD with concurrent STEMI. However, an optimal cut-off value of D-dimer in such population remains unclear. Therefore, the aim of this study was to elucidate the optimal D-dimer threshold in patients clinically diagnosed with STEMI.

METHODS

This retrospective cohort study was conducted at two tertiary care centers between 2014 and 2019. Patients clinically diagnosed with STEMI who underwent serum D-dimer measurement on hospital arrival were included. The primary outcome was the diagnosis of AAD. The area under the receiver operating characteristic curve (AUROC) for D-dimer values to diagnose AAD was evaluated, particularly in patients with low to moderate risks of AAD (1 of ADD-RS). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated with several cut-off values.

RESULTS

A total of 322 patients were included, and 28 were diagnosed with AAD. The AUROC for D-dimer to diagnose AAD was 0.970 (95% confidence interval: 0.948-0.993) in 262 patients with 1 of ADD-RS. If D-dimer ≥750 ng/mL was used as a cut-off value, sensitivity, specificity, PPV and NPV were 100%, 86.4%, 37.7%, and 100%, respectively. AAD could be denied in 209 (79.8%) patients using the cut-off value (D-dimer <750 ng/mL).

CONCLUSIONS

Serum D-dimer ≥750 ng/mL exhibited high sensitivity and NPV to diagnose AAD with concurrent STEMI, while the ADD-RS originally utilized ≥500 ng/mL as a cut-off for any suspected AAD. A point-of-care D-dimer measurement with the new cut-off would be useful to rule-out AAD among patients with STEMI.

Diagnostic performance and predictive value of D-dimer testing in patients referred to the emergency department for suspected myocardial infarction

PURPOSE

The study sought to assess the performance of D-dimer testing for the diagnosis of acute coronary syndrome (ACS) and prediction of outcomes in patients admitted for suspected myocardial infarction (MI).

RESULTS

A total of 3,557 patients with suspected ACS presenting to a single center with a broad range of symptoms including atypical chest pain were retrospectively recruited between 02/2012-01/2019. Of the study cohort, 435 patients had unstable angina (UA), 420 non-ST-segment elevation myocardial infarction (NSTEMI), 22 ST-segment elevation myocardial infarction (STEMI), and 2,680 non-coronary chest pain. Plasma D-dimer concentrations in patients with hs-cTnT > 14 ng/L differed significantly from those with hs-cTnT < 14 ng/L (1.5 ± 3.6 mg/L vs. 0.5 ± 0.8 mg/L; p < 0.0001). Positive predictive value for a final diagnosis of ACS increased proportionally to rising D-dimer concentrations. The area under the curve (AUC) to discriminate STEMI from non-coronary chest pain (AUC 0.729, 95% confidence interval [CI] 0.71-0.75) was moderate and differed not significantly to UA (AUC 0.595, 95% CI 0.58-0.61; p = 0.0653). During a median follow-up of 29 months, higher D-dimer was associated with a significantly increased risk of recurrent MI (quartile 4 vs. 1: hazard ratio [HR], 6.9 [95% CI 1.2-39.9]; p < 0.0001) and higher all-cause mortality (HR, 17.4 [95% CI 4.3-69.9]; p < 0.0001). D-dimer was an independent predictor of all-cause mortality (p < 0.0001) and subsequent MI events (p = 0.0333).

CONCLUSIONS

D-dimer testing revealed great potential to provide independent prognostic information on recurrent MI and all-cause mortality. However, D-dimers do not improve the diagnostic performance except if values exceed the 95th percentile.

Utility of Human Neutrophil Lipocalin as a Diagnosing Biomarker of Prosthetic Joint Infection: A Clinical Pilot Study

Purpose

The discrimination of prosthetic joint infection (PJI) from aseptic failure is regarded as a major clinical challenge. The key function of human neutrophil lipocalin (HNL) in regulating bacterial infection rationalizes its potential as a biomarker to diagnose PJI. This work evaluated the accuracy of serum human neutrophil lipocalin as a biomarker to diagnose PJI.

Methods

This prospective cohort study enrolled altogether 58 patients suffering from miserable knee or hip arthroplasty and receiving revision surgery from 2018 to 2020. Related laboratory and clinical information of these patients were retrieved. Following the Musculoskeletal Infection Society (MSIS) criteria, the diagnosis of PJI was conducted. Collecting preoperative blood samples, we measured HNL by the standard assay. Thereafter, plotting the receiver-operating characteristic curve (ROC), the area under the curve (AUC) values were calculated to analyze the diagnosis accuracy.

Results

According to the MSIS criteria, 38 cases (65.5%) were classified into the PJI group, while 20 (34.5%) into the aseptic loosening group, with age ranging from 38 to 87 (median, 66.9) years. The median serum HNL level of the PJI patients was 199.01 (range, 85.34–357.79) ng/mL, significantly higher as compared with that of 64.81 (range, 20.73–157.89) ng/mL of the aseptic loosening group. Using the Youden index, the optimal threshold value was 105.1ng/mL, while the specificity, sensitivity, and AUC were 85.0%, 81.6%, and 0.919, respectively.

Conclusion

Serum HNL is the creditable test that can be employed as the laboratory biomarker to screen PJI. The threshold HNL level is 105.1 ng/mL, which may distinguish PJI from aseptic failure.

Surviving the Storm: Cytokine Biosignature in SARS-CoV-2 Severity Prediction

Simple Summary

The world has been stricken mentally, physically, and economically by the COVID-19 virus. However, while SARS-CoV-2 viral infection results in mild flu-like symptoms in most patients, a number of those infected develop severe illness. These patients require hospitalization and intensive care. The severe disease can spiral downwards with eventual severe damage to the lungs and failure of multiple organs, leading to the individual’s demise. It is necessary to identify those who are developing a severe form of illness to provide early management. Therefore, it is crucial to learn about the mechanisms and chemical mediators that lead to critical conditions in SARS-CoV-2 infection. This paper reviews studies regarding the individual chemical mediators, pathways, and means that contribute to worsening health conditions in SARS-CoV-2 infection.

Abstract

A significant part of the world population has been affected by the devastating SARS-CoV-2 infection. It has deleterious effects on mental and physical health and global economic conditions. Evidence suggests that the pathogenesis of SARS-CoV-2 infection may result in immunopathology such as neutrophilia, lymphopenia, decreased response of type I interferon, monocyte, and macrophage dysregulation. Even though most individuals infected with the SARS-CoV-2 virus suffer mild symptoms similar to flu, severe illness develops in some cases, including dysfunction of multiple organs. Excessive production of different inflammatory cytokines leads to a cytokine storm in COVID-19 infection. The large quantities of inflammatory cytokines trigger several inflammation pathways through tissue cell and immune cell receptors. Such mechanisms eventually lead to complications such as acute respiratory distress syndrome, intravascular coagulation, capillary leak syndrome, failure of multiple organs, and, in severe cases, death. Thus, to devise an effective management plan for SARS-CoV-2 infection, it is necessary to comprehend the start and pathways of signaling for the SARS-CoV-2 infection-induced cytokine storm. This article discusses the current findings of SARS-CoV-2 related to immunopathology, the different paths of signaling and other cytokines that result in a cytokine storm, and biomarkers that can act as early signs of warning for severe illness. A detailed understanding of the cytokine storm may aid in the development of effective means for controlling the disease’s immunopathology. In addition, noting the biomarkers and pathophysiology of severe SARS-CoV-2 infection as early warning signs can help prevent severe complications.

A new method of monitoring catheter-directed thrombolysis for deep venous thrombosis-application of D-dimer and fibrinogen testing

BACKGROUND

Catheter-directed thrombolysis (CDT) is one of the main treatment methods for acute deep venous thrombosis (DVT), which has the characteristics of long treatment time and large dosage of thrombolytic drugs. In the absence of good monitoring methods, problems such as low thrombolytic efficiency and high risk of bleeding are easy to occur.

OBJECTIVE

To evaluate the value of D-dimer (D-D) and fibrinogen (FIB) testing as a thrombolysis-monitoring method during CDT for acute DVT.

METHODS

Twenty patients with acute DVT were divided into group A and group B. During CDT, the D-D and FIB testing every 8 h were used in group A, and the venography and FIB testing every 24 h in group B. The thrombolysis rate, thrombolysis time, urokinase dosage, and X-ray radiation dose were compared.

RESULTS

The thrombolysis rate in group A was significantly higher than that in group B (p < 0.05), but the number of venography and radiation dose were significantly lower than those in group B (p < 0.05).

CONCLUSION

D-D and FIB testing can improve the thrombolysis rate, reduce the risk of bleeding, and decrease the number of angiograms and X-ray radiation dose during CDT.

D-dimer: an analyte with increasing application in Covid-19 infection

INTRODUCTION

: D- Dimer levels from peripheral blood are increasingly used to assess various pathological conditions. Initially an area for haematologists, now this analyte is evaluated more extensively from many specialities of medicine. Covid-19 infection has not only added a new dimension to D-Dimer level assessment in this disease but has also shed newer lights to the underlying pathophysiological mechanisms for its elevation in this disease.

AREAS COVERED

Innate variability in measuring D- Dimer levels, Impact of various techniques in measuring D- Dimer, non availability of uniform controls and standards, molecular heterogeneity of the product, how it is produced. Reasons for raised D- Dimer in covid-19 infection. D- Dimer in other pathological states. Articles with relevant key words from 1990 searched in PubMed were utilized for review.

EXPERT OPINION

: D-Dimer has important application in diagnosis, prognosis, management and understanding various conditions. Its level can rise with increased coagulability of blood, sepsis, cytokine storm and snake bite etc. Renal function, age influences its reference ranges. Units of measurement, its expression varies in different reports needing international standardization. In Covid-19 infection its levels correlate with stage of the disease, pathology and complications.

Elucidating the Correlation of D-Dimer Levels with COVID-19 Severity: A Scoping Review

Aims

The review explores the findings of previous studies to elucidate the association between levels of D-dimer and COVID-19 severity and prognosis. In addition, we assessed the efficiency of anticoagulant therapies in reducing COVID-19 severity and improving the prognosis of the patients.

Materials and Methods

A comprehensive literature review was conducted using MEDLINE/PubMed databases, Scopus, and Web of Science with the help of keywords "COVID-19," "D-Dimer," "Thrombosis," "Fibrin network," "Anticoagulant therapy," "Inflammation," and "disease severity." Based on all these articles and clinical experience, a scoping review was constructed and the full texts of the articles that were retrieved were accessed.

Results

A D-dimer is a complex protein molecule that is formed during plasmin-mediated degradation of the fibrin network. Thus, it serves as a marker of thrombotic activity. On the other hand, in addition to severe respiratory distress and reduction in pulmonary gas exchange, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also triggers prothrombotic changes in the infected individuals. The levels of D-dimer have been postulated to be positively associated with the degree of disease severity among COVID-19 patients.

Conclusions

It has been postulated that D-dimer could potentially be used as a biomarker to predict the prognosis and outcome of COVID-19 patients at the time of admission to hospitals and facilitate more personalized and efficient clinical management that could significantly reduce the mortality rate of such patients and allow more rapid recovery.

Analytical performance of a new immunoturbidimetric D‐dimer assay and comparison with available assays

Background

The routine D‐dimer quantification to exclude venous thromboembolism has led to the development of many assays, the usefulness of which depends on their reliability and performance.

Objective

We evaluated the analytical performances of the immunoturbidimetric Yumizen G DDi 2 assay (HORIBA Medical, Montpellier, France) performed on the Yumizen G800 analyzer and compared it with other available D‐dimer assays.

Methods

Within‐run and between‐run imprecision were evaluated using low‐ and high‐level quality‐control plasma samples. Interference due to hemolysis, icterus, lipemia, rheumatoid factor (RF), or heterophilic antibodies (human antimouse antibodies [HAMAs]) was evaluated by spiking plasma samples with hemolysate, bilirubin, Intralipid, RF, or HAMAs. The measurements obtained with the different D‐dimer assays were compared using Passing‐Bablok regression analysis and Bland‐Altman plot method, using fresh citrated plasma samples collected from 66 consecutive routine patients with a wide range of D‐dimer concentrations.

Results

Within‐ and between‐run variation coefficients for the Yumizen G DDi 2 assay ranged from 1.7% to 5.8% and from 2.8% to 5.5%, respectively. Hemolysis and icterus did not have any effect up to 10 g/L hemoglobin and 300 mg/L bilirubin. Lipemia seemed to generate an underestimation of D‐dimer concentration when the Intralipid concentration was >5 g/L. RF and HAMAs did not have any effect. The Passing‐Bablok and Bland‐Altman analyses showed small differences with other available D‐dimer assays, which were more pronounced with increasing values.

Conclusions

Its analytical performances and main technical features indicate that the new Yumizen G DDi 2 assay is suitable for the rapid quantification of D‐dimer in clinical hemostasis laboratories.

Transiently elevated D-dimer levels post-concentrated ascites reinfusion therapy cannot be used to predict deep vein thrombosis-pulmonary embolism

AIM

Cell-free and concentrated ascites reinfusion therapy (CART) is useful for treating malignant ascites. We have previously experienced cases with no DVT-PE despite a marked elevation in D-dimer post-CART. In this study, we assessed the changes in the D-dimer levels in patients who received CART and investigated the association between elevated D-dimer levels and occurrence of DVT-PE.

METHODS

We performed an observational retrospective analysis of patients with gynecological malignancies treated with CART between March 2018 and April 2021. The selected patients had their D-dimer levels measured before and post-CART. The presence or absence of clinical DVT-PE findings was then examined, and contrast-enhanced computed tomography was performed using a DVT protocol in some cases.

RESULTS

Eleven patients received 17 CART procedures in this study. Patients of 16 procedures (94.1%) showed a significant elevation in D-dimer levels on day 1 post-CART. Changes in D-dimer levels were monitored in these patients of 16 procedures. In all 16 cases, the D-dimer levels decreased after day 2 post-CART. Only one patient, who presented with respiratory failure, out of the patients of 16 procedures (6.2%) with elevated D-dimer levels on day 1 had PE.

CONCLUSIONS

D-dimer elevation after CART is likely to be transient and a false-positive. None of the patients in this study had PE if they were asymptomatic after CART, there is no need to strongly suspect PE only by D-dimer elevation. In conclusion, D-dimer measurement immediately post-CART is not helpful in predicting the diagnosis of DVT-PE.