Role of D-dimers in diagnosis of venous thromboembolism

The Optimal Cutoff Level of D-Dimer during Pregnancy to Exclude Deep Vein Thrombosis, and the Association between D-Dimer and Postpartum Hemorrhage in Cesarean Section Patients

OBJECTIVE

The main purpose was to clarify the optimal D-dimer cutoff level during pregnancy to exclude deep vein thrombosis (DVT) prior to Cesarean section. The secondary purpose was to determine whether D-dimer can predict severe postpartum hemorrhage (PPH) in Cesarean section patients.

METHODS

Two hundred and seventy eight elective Cesarean section cases were enrolled. Clinical factors and blood parameters at 34-37 weeks of gestation were analyzed. To detect DVT, lower extremities veins were examined using color Doppler ultrasonography in cases with D-dimer level ≥ 1.5 μg/mL. In addition, postpartum blood loss amounts during Cesarean section were recorded.

RESULTS

Five DVT cases occurred in 250 singleton pregnancies, and 2 DVT cases occurred in 28 twin pregnancies. The overall incidence of DVT was 2.5%. The D-dimer level was higher in DVT cases than in non-DVT cases (3.84±1.97 vs. 2.31±1.48 μg/mL, P<0.01). The optimal D-dimer cutoff level was 2.6 μg/mL with a negative predic tive value of 99.5%, and sensitivity of 85.7%. PPH during Cesarean section was positively correlated with D-dimer level in all pregnancies. However, this relationship disappeared after excluding twin pregnancies.

CONCLUSION

A D-dimer level < 2.6 μg/mL at 34-37 weeks of gestation has the potential to exclude DVT. D-dimer can be an independent predictor for severe PPH for all Cesarean section cases, including twin pregnancies.

Rate of venous thromboembolism in a prospective all-comers cohort with COVID-19

COVID-19 is associated with a variety of clinical complications including coagulopathy, which frequently results in venous thromboembolism (VTE). Retrospective analyses reported a markedly increased rate of VTEs in COVID-19. However, most recent studies on coagulopathy in COVID-19 were only focused on critically ill patients, and without suitable control groups. We aimed to evaluate the rate of VTEs in an all-comers cohort with suspected COVID-19 during a 30-days follow-up period. We also studied the level of D-dimers and their association with the course of disease. In our prospective single-center study (DRKS00021206, 03/30/2020), we analyzed 190 patients with suspected COVID-19 admitted to the emergency department between March and April 2020. Forty-nine patients were SARS-CoV-2 positive (25.8%). The 141 SARS-CoV-2-negative patients served as control group. After completion of a 30-days follow-up, VTE was diagnosed in 3 patients of the SARS-CoV-2-positive group (6.1%, amongst these 2 ICU cases) versus 5 patients in the SARS-CoV-2-negative group (3.5%), however the difference was not statistically significant (p = 0.427). 30-days mortality was similar in both groups (6.1% vs. 5%, p = 0.720). Disease severity correlated with the maximum level of D-dimers during follow-up in COVID-19. The rate of VTE was numerically higher in SARS-CoV-2 positive all-comers presenting with suspected COVID-19 as compared to well-matched controls suffering from similar symptoms. VTEs in the COVID-19 group predominantly occurred in ICU courses. The maximum level of D-dimers during follow-up was associated with disease severity in COVID-19, whereas the level of D-dimers at admission was not.

Prevalence and Risk Factors of Thromboembolism among Patients With Coronavirus Disease-19: A Systematic Review and Meta-Analysis

Emerging evidence shows that the recent pandemic of coronavirus disease 19 (COVID-19) is characterized by coagulation activation and endothelial dysfunction. This increases the risk of morbidity, mortality and economic loss among COVID-19 patients. Therefore, there was an urgent need to investigate the extent and risk factors of thromboembolism among COVID-19 patients. English-language based databases (PubMed, Cumulative Index to Nursing and Allied Health Literature, EMBASE, and Cochrane library) were exhaustively searched to identify studies related to prevalence of thromboembolism among hospitalized COVID-19 patients. A random-effects model was employed to estimate the pooled prevalence of thromboembolism. The pooled prevalence of thrombotic events was computed using STATA 16.0 software. Heterogeneity analysis was reported using I2. A total of 19 studies with 2,520 patients with COVID-19 were included. The pooled prevalence of thrombotic events of hospitalized patients with COVID-19 was 33% (95% CI: 25-41%, I2 = 97.30%, p < 0.001) with a high degree of heterogeneity across studies. Elevated D-dimer hospitalized in the intensive care unit and being under mechanical ventilation were the most frequently associated factors for the development of thrombotic events. The pooled prevalence of thrombotic events in COVID-19 patients was 33%. The prevalence of thrombotic event is variables on the basis of study design and study centers. Several risk factors such as, elevated D-dimer, hospitalized in the intensive care unit and being under mechanical ventilation, were the most frequently reported risk factors identified. Therefore, healthcare professionals should consider these risk factors to optimally manage thromboembolism in COVID-19 patients.

Venous thromboembolism and palliative care

The management of cancer-associated thrombosis (CAT) is largely informed by data from adequately powered randomised control trials. However, their exclusion criteria have invariably rendered the study populations unrepresentative of those seen day-to-day by palliative care practitioners.Recent observational data has given insights into the unique challenges of CAT management within the palliative care setting including the natural history of thrombosis in advanced cancer and end-of-life decision making around anticoagulationDespite developments and some on-going uncertainties, one constant remains; the patient and their experiences. We should, wherever possible, involve them in the decision-making process particularly where the evidence is lacking. By appreciating the values and concerns of our patients, we shall be able to plan care that most meets their needs.

Gestation-specific D-dimer reference ranges: a cross-sectional study

OBJECTIVE

To establish a gestation-specific reference range for D-dimer in healthy pregnant women with a singleton pregnancy using the Auto-Dimer assay.

DESIGN

Cross-sectional study

SETTING

Cork University Maternity Hospital, Ireland.

POPULATION

Healthy pregnant women attending for routine antenatal care.

METHODS

Simultaneous-quantile regression was performed to construct a median, 5th percentile, and 95th percentile, model of normal pregnancy D-dimer concentration versus gestational week, ranging from week 6 to 42. Additionally, pair-wise Mann-Whitney U-tests were performed to compare distributions of D-dimer concentrations for each of the four discrete gestational sampling windows with the distribution of D-dimer concentrations 48 hours postpartum.

MAIN OUTCOME MEASURES

D-dimer concentrations (ng/ml) during normal gestation (approximately week 6 to week 42).

RESULTS

Seven hundred and sixty healthy pregnant women were investigated between gestational age week 5 and 48 hours postpartum. There was a clear steady increase in median D-dimer concentrations over the complete gestational period. Additionally, the 95th centile estimates for all gestational time-points were above the accepted non-pregnancy normal cut-off concentration (224 ng/ml). The results of the Mann-Whitney U-tests suggested that the long-term postnatal return to normal D-dimer concentrations begins in the immediate postpartum period.

CONCLUSIONS

We found that there is a continuous increase in D-dimer concentrations across all gestations. This research is potentially beneficial to future diagnosis of venous thromboembolism (VTE) in pregnancy using the new recommended 95th centile potential cut-offs. Possible further investigation involves an observational study comparing D-dimer concentrations in women with proven DVT with those that don't, generating likelihood ratios.

Diagnostic tests and strategies in venous thromboembolism

Venous thromboembolism (VTE) is a term including deep vein thrombosis (DVT) and pulmonary embolism (PE). Timely and accurate diagnosis of both is essential as delayed or missed diagnoses can result in death or longer term complications. Patients with suspected DVT should initially undergo a pretest probability Wells score. Depending on pretest probability Wells score they should then either proceed to two-point ultrasound scanning or D-dimer testing. Likewise, patients suspected of PE should undergo a two-level PE Wells score, and, if scored likely, a computed tomography pulmonary angiogram (CTPA), or, if there is a low pretest probability score, D-dimer testing. If positive, patients should undergo CTPA. Ventilation perfusion scanning (V/Q scan) or V/Q SPECT should be considered in place of CTPA if there is allergy to contrast media or renal impairment.

Management of venous thromboembolism in patients with cancer

The association between venous thromboembolism and cancer has been recognized for over 140 years. This article reviews current prevention, diagnosis and treatment of cancer-related venous thromboembolism, and highlights emerging anticoagulants and the possible anticancer effects of anticoagulants such as low molecular weight heparins.

[Utility of D-dimer assay for diagnosing pulmonary embolism: single institute study]

BACKGROUND

Pulmonary embolism (PE) presents with diverse non-specific signs and symptoms and its diagnosis mainly depends on diagnostic imaging tests which are laborious and not cost-effective, and only a small proportion of patients with suspected PE actually have the disease. The aim of this study was to analyze the utility of D-dimer test for diagnosing PE by categorizing patients into 'PE likely' and 'PE unlikely' groups using Wells score for clinical probability.

METHODS

One hundred forty consecutive patients with clinically suspected PE, in whom D-dimer and imaging tests were performed were enrolled. Dignosis of PE was made when the imaging tests were positive. Wells scores were retrospectively assigned and the dignostic utility of D-dimer test was analyzed.

RESULTS

Of the 140 patients studied, D-dimer test was positive in 97 and diagnostic imaging tests revealed PE, deep vein thrombosis (DVT), and PE+DVT in 24, 3, and 7 patients, respectively. For the diagnosis of PE, D-dimer test with cutoff value of > or =230 ng/mL showed sensitivity, specificity, and negative predictive value of 96.8%, 39.6%, and 97.7%, respectively. These values were 96.3%, 37.9%, and 91.7% in 'PE likely' group (n=56), and 100%, 38.8%, and 100% in 'PE unlikely' group (n=84). Among 43 patients with D-dimer values of <230 ng/mL, only one patient was diagnosed with PE, who belonged to the 'PE likely' group.

CONCLUSIONS

D-dimer test cannot be used as a stand-alone test to diagnose PE, but it can be helpful for exclusion of PE especially in 'PE unlikely' group according to Wells score.

African-American ethnicity is associated with higher plasma levels of D-dimer in adults with hypertension

BACKGROUND

African Americans with hypertension have higher cardiovascular morbidity and mortality than hypertensives from other ethnic groups. Plasma D-dimer, a fragment generated from fibrin during lysis of mature clot in vivo, is a predictor of adverse cardiovascular events.

OBJECTIVE

We investigated whether plasma levels of D-dimer differ between African American (AA) and non-Hispanic white (NHW) adults with hypertension.

METHODS

Participants included 933 AA (65 +/- 9 years, 72% women) and 821 NHW (61 +/- 9 years, 56% women) from the community. D-dimer was measured using an immunoturbidimetric assay. Multivariable regression analyses, stratified by gender, were performed to assess whether AA ethnicity was associated with D-dimer levels after adjustment for age, body mass index (BMI), total and high-density lipoprotein (HDL) cholesterol, systolic blood pressure, diabetes, history of smoking, medication (statin and aspirin) use, lifestyle variables (physical activity, alcohol intake, and education), estimated glomerular filtration rate (eGFR), and a marker of inflammation, C-reactive protein (CRP).

RESULTS

D-dimer levels were higher in AA men and women than in their NHW counterparts (mean +/- SD; men 256 +/- 199 vs. 190 +/- 183 ng mL(-1), P < 0.001; women, 290 +/- 233 vs. 225 +/- 195 ng mL(-1), P < 0.001). In both sexes, after adjustment for age, conventional risk factors, medication use, and lifestyle variables, AA ethnicity remained associated with higher D-dimer levels (P = 0.002 in men, P = 0.006 in women). These associations remained significant after additional adjustment for eGFR and plasma CRP (P = 0.003 in men, P < 0.0001 in women).

CONCLUSIONS

Among adults with hypertension, AA ethnicity was independently associated with higher plasma levels of D-dimer.

Management of venous thromboembolism in the palliative care setting

Recent literature has highlighted the unique challenges facing professionals involved with the management of venous thromboembolism (VTE) in cancer patients. Although research favours the use of low molecular weight heparin (LMWH) rather than warfarin, no studies have been conducted exclusively in the palliative care population. Likewise, active treatment may not always be appropriate in the advanced cancer patient. This paper highlights the issues to be considered when facing a palliative care patient and suspected VTE. In particular, consideration must be given to the practicalities and acceptability of investigating suspected VTE, the dose and length of anticoagulation, and management of the patient nearing death. An understanding of the current evidence must be applied to the individual patient, taking into account their needs and wishes.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

The challenges of managing cancer related venous thromboembolism in the palliative care setting

Cancer patients with venous thromboembolism (VTE) pose particular management challenges since they have an increased risk of bleeding and recurrent thrombosis compared to the non-cancer population. Also, as the disease progresses so do the hazards of anticoagulation, and patients in the palliative stages of their cancer could be viewed as a separate disease group with respect to diagnosis and management. As the focus from curative treatment moves towards symptom control, physicians face several challenges in providing the most appropriate care. Palliative care patients have rarely been included in research on VTE and the supporting evidence needs to be extrapolated cautiously. Quality of life aspects of VTE and their management may be a more appropriate outcome measure in this stage of disease than radiological end points. This paper looks at the challenges facing professionals in the management of VTE in the advanced cancer patient.

Thromboembolic Disorders in Cancer

Complex factors, including substances in cancer cells, cancer treatment effects, and venous stasis associated with chronic illness, blood vessel wall injury, and immobility, interact to place patients with cancer at risk for thrombosis. This article describes the etiology, clinical manifestations, diagnostic tests, and treatments for venous and pulmonary emboli associated with cancer. It explores the nurse's role in assessing patients who are at risk, managing symptomatic thrombosis and primary and secondary prevention of emboli, and administering anticoagulant therapy. As growing numbers of patients are treated in outpatient settings, oncology nurses play a critical role in the coordination of care for patients at risk for thrombosis. A nursing care plan summarizes key nursing strategies for assessment and intervention.

Subklaviathrombose nach Portanlage bei metastasiertem Melanom

The use of implanted central venous catheters with ports has become almost irreplaceable in clinical treatment of cancer patients with advanced disease. It improves the patient's quality of life and simplifies medical treatment. For safe use during outpatient follow-up treatment, possible complications such as wound infections, thrombosis or even pulmonary embolism have to be considered. The incidence of catheter-associated thrombosis in cancer patients has been estimated as 25-66% in screening evaluations. Clinical symptoms were present in only in 6-28% of all patients with diagnosed thromboses. We report on a patient with metastatic malignant melanoma, who developed a deep arm vein thrombosis two weeks after port implantation. The prognosis of deep arm vein thrombosis is determined by the development of pulmonary embolism (8-36%). In such cases, early diagnosis and treatment are essential for the patient's survival.

Duration of Treatment of Deep Vein Thrombosis: Time for a New Approach?

The American College of Chest Physicians Consensus Conference on Antithrombotic Therapy recommends that patients with initial idiopathic deep vein thrombosis (DVT) receive treatment for at least 6-12 months. However, controversy exists as to what treatment duration and intensity are optimal. Some investigators have suggested that it may be feasible to identify patients who are at low risk and those who are at high risk of recurrent venous thromboembolism. If patients can be stratified according to risk, then it might be safe and effective to withdraw oral anticoagulation therapy in those at low risk of recurrence and continue the therapy in those at high risk. Parameters that have been used to attempt to stratify patients with idiopathic DVT according to risk are D-dimer levels, resolution of thrombosis on ultrasound, and sex.

Latex D-dimer signal in in situ femoral vein thrombus in swine and effect of minidose exogenous tissue plasminogen activator bolus

STUDY OBJECTIVES

We created in situ femoral vein thrombi in swine to investigate the response of the latex d-dimer signal to acute in situ venous thrombosis, and to determine the minimum dose of exogenous bolus tissue plasminogen activator (t-PA) required to significantly elevate the d-dimer signal.

STUDY DESIGN

We studied seven swine (20 to 22 kg) under pentobarbital anesthesia. A 6-cm segment of the proximal femoral vein was surgically exposed and briefly ligated. Thrombin, 250 U, was then injected into the isolated femoral vein segment to create an in situ clot. After clot formation was documented to be complete between the ligatures, they were then released. D-dimer levels were then measured every 15 min for 1 h before and 1 h after clot formation with ligatures released. Time-response curves to establish timing of peak t-PA effect were performed, and then escalating dose-response curves of d-dimer level to minidose t-PA were plotted.

RESULTS

After formation of the clot, the release of ligatures resulted in no change in d-dimer levels over 1 h (p = 0.62) in all swine. When a time-response curve to exogenous t-PA bolus in the presence of femoral clot was plotted, there was a maximal increase in d-dimer signal at 30 min after bolus t-PA administration. The subsequent dose-response curves for escalating fivefold boluses of minidose t-PA showed an increase in d-dimer signal at doses of 0.8 mg (p = 0.03) and 4 mg (p = 0.003).

CONCLUSION

We conclude the following: (1) in situ femoral vein clot formation does not elevate d-dimer signal for 1 h after ligature release; (2) minidose t-PA boluses of 0.8 mg and 4 mg significantly elevated the latex d-dimer signal above baseline; and (3) there is a potential role of minidose t-PA in enhancing the d-dimer signal in in situ deep venous thrombosis.

Pulmonary embolism

Pulmonary embolism (PE) is a common illness that can cause death and disability. It is difficult to detect because patients present with a wide array of symptoms and signs. The clinical setting can raise suspicion, and certain inherited and acquired risk factors predispose susceptible individuals. D-dimer concentration in blood is the best laboratory screening test, and chest CT has become the most widespread imaging test. Treatment requires rapid and accurate risk stratification before haemodynamic decompensation and the development of cardiogenic shock. Anticoagulation is the foundation of therapy. Right-ventricular dysfunction on echocardiography and higher than normal concentrations of troponin identify high-risk patients who might need escalation of therapy with thrombolysis or embolectomy even if the blood pressure is normal on presentation. When patients are admitted to medical wards or when patients undergo surgery, their physicians should prescribe prophylactic measures to prevent PE. After hospital discharge, prophylaxis should continue for about a month for patients at high risk of thromboembolism.

Thrombotic and nonthrombotic pulmonary arterial embolism: spectrum of imaging findings

Along with clinical examination and laboratory tests, imaging plays a key role in the diagnosis of pulmonary embolism. Multi-detector row helical computed tomography (CT) is particularly helpful in the diagnosis of acute pulmonary thromboembolism (PTE) owing to its capacity to directly show emboli as intravascular filling defects. Although parenchymal abnormalities at CT are nonspecific for acute PTE, they may contribute to a correct diagnosis of chronic PTE, the characteristic helical CT features of which are similar to its angiographic features and include webs or bands, intimal irregularities, abrupt narrowing or complete obstruction of the pulmonary arteries, and "pouching defect." Nonthrombotic pulmonary embolism is an uncommon condition but is sometimes associated with specific imaging findings, including discrete nodules with cavitation (septic embolism), widespread homogeneous and heterogeneous areas of increased opacity or attenuation that typically appear 12-24 hours after trauma (fat embolism), and fine miliary nodules that subsequently coalesce into large areas of increased opacity or attenuation (talcosis). Knowledge of appropriate imaging methods and familiarity with the specific imaging features of pulmonary embolism should facilitate prompt, effective diagnosis.

The utility of pretest probability assessment in patients with clinically suspected venous thromboembolism

The assessment of pretest probability (PTP), with stratification into low-, intermediate- and high-risk groups is an essential initial step in the current diagnostic management of patients with suspected venous thromboembolism (VTE). In combination with additional information, it reduces the need for initial and supplementary imaging, and allows considerable refinement of the posterior probability of VTE following non-invasive imaging. PTP may be assessed either empirically or by using various decision rules or scoring systems, the best known of which are the simplified Wells scores for suspected deep vein thrombosis (DVT) and pulmonary embolism (PE), and the Geneva score for suspected PE. Each of these approaches shows similar directional and categorical accuracy, and has been validated as facilitating clinically useful classification of the PTP, although an overview of data suggests that fewer patients tend to be classified as low PTP when assessed empirically. This group is the most important to identify, as several outcome studies have shown that imaging and treatment are safely obviated in outpatients with suspected DVT or PE who have a low PTP in combination with negative d-dimer testing, a subgroup accounting for up to half of all patients studied. Hence, while probably not of critical importance, the explicit approach offered by scoring systems might be preferred over empirical assessment, particularly when used by more junior staff.

Normal D-dimer levels in emergency department patients suspected of acute pulmonary embolism

OBJECTIVES

We sought to determine:1) whether normal D-dimer enzyme-linked immunosorbent assay (ELISA) assays predicted the absence of pulmonary embolism (PE) in the high-volume emergency department (ED) of the Brigham and Women's Hospital, and 2) whether ED physicians accepted normal D-dimer levels as confirmation of no PE without further diagnostic testing such as lung scanning, chest computed tomography (CT) scanning, or pulmonary angiography.

BACKGROUND

Although the plasma D-dimer ELISA is a sensitive screening test for excluding acute PE, this laboratory marker has not been widely integrated into clinical algorithms such as creatine kinase-MB fraction or troponin testing for acute myocardial infarction.

METHODS

We mandated that ED physicians order D-dimer ELISA tests on all patients suspected of acute PE. We reviewed the clinical record of each ED patient initially evaluated for suspected PE during the year 2000. We determined whether additional imaging tests for PE were obtained and whether the final diagnosis was PE.

RESULTS

Of 1,106 D-dimer assays, 559 were elevated and 547 were normal. Only 2 of 547 had PE despite a normal D-dimer. The sensitivity of the D-dimer ELISA for acute PE was 96.4% (95% confidence interval [CI]: 87.5% to 99.6%), and the negative predictive value was 99.6% (95% CI: 98.7% to >99.9%). Nevertheless, 24% of patients with normal D-dimers had additional imaging tests for PE.

CONCLUSIONS

The D-dimer ELISA has a high negative predictive value for excluding PE. By paying more attention to normal D-dimer results, fewer chest CT scans and lung scans will be required, and improvements may be realized in diagnostic efficiency and cost reduction.