Multicentre evaluation of a new point-of-care test for the quantitative determination of D-dimer

Serum D-dimer level as a biomarker for identifying patients with isolated injury to prevent unnecessary whole-body computed tomography in blunt trauma care

Background

Unnecessary whole-body computed tomography (CT) may lead to excess radiation exposure. Serum D-dimer levels have been reported to correlate with injury severity. We examined the predictive value of serum D-dimer level for identifying patients with isolated injury that can be diagnosed with selected-region CT rather than whole-body CT.

Methods

This single-center retrospective cohort study included patients with blunt trauma (2014–2017). We included patients whose serum D-dimer levels were measured before they underwent whole-body CT. “Isolated” injury was defined as injury with Abbreviated Injury Scale (AIS) score ≤ 5 to any of five regions of interest or with AIS score ≤ 1 to other regions, as revealed by a CT scan. A receiver operating characteristic curve (ROC) was drawn for D-dimer levels corresponding to isolated injury; the area under the ROC (AUROC) was evaluated. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for several candidate cut-off values for serum D-dimer levels.

Results

Isolated injury was detected in 212 patients. AUROC was 0.861 (95% confidence interval [CI]: 0.815–0.907) for isolated injury prediction. Serum D-dimer level ≤ 2.5 μg/mL was an optimal cutoff value for predicting isolated injury with high specificity (100.0%) and positive predictive value (100.0%). Approximately 30% of patients had serum D-dimer levels below this cutoff value.

Conclusion

D-dimer level ≤ 2.5 μg/mL had high specificity and high positive predictive value in cases of isolated injury, which could be diagnosed with selected-region CT, reducing exposure to radiation associated with whole-body CT.

Soluble CD14 as a Diagnostic Biomarker for Smear-Negative HIV-Associated Tuberculosis

Sputum smear-negative HIV-associated active tuberculosis (TB) is challenging to diagnose. CD14 is a pattern recognition receptor that is known to mediate monocyte activation. Prior studies have shown increased levels of soluble CD14 (sCD14) as a potential biomarker for TB, but little is known about its value in detecting smear-negative HIV-associated TB. We optimized a sandwich ELISA for the detection of sCD14, and tested sera from 56 smear-negative South African (39 culture-positive and 17 culture-negative) HIV-infected pulmonary TB patients and 24 South African and 43 US (21 positive and 22 negative for tuberculin skin test, respectively) HIV-infected controls. SCD14 concentrations were significantly elevated in smear-negative HIV-associated TB compared with the HIV-infected controls (p < 0.0001), who had similar concentrations, irrespective of the country of origin or the presence or absence of latent M. tuberculosis infection (p = 0.19). The culture-confirmed TB group had a median sCD14 level of 2199 ng/mL (interquartile range 1927-2719 ng/mL), versus 1148 ng/mL (interquartile range 1053-1412 ng/mL) for the South African controls. At a specificity of 96%, sCD14 had a sensitivity of 95% for culture-confirmed smear-negative TB. These data indicate that sCD14 could be a highly accurate biomarker for the detection of HIV-associated TB.

The Clinical Utility of Makeshift Beds in Disaster Shelters

Objective

Strong earthquakes have been reported to increase the incidence of diseases. One reason for these increases may be the stress from the poor living environment for evacuees in disaster shelters. To reduce stress, makeshift cardboard beds were introduced in shelters in the Ishinomaki region, one of the areas heavily damaged by the Great East Japan Earthquake, 4 months after the earthquake. The study was performed to determine whether use of the beds offered a reduction in the disease burden.

Methods

Blood pressure and blood D-dimer values, often used as diagnostic tests for venous thrombosis, were checked. The timed Up & Go (TUG) test, which assesses functional mobility; a questionnaire survey about symptoms (cough, insomnia, and lumbago); and an SF-8 health survey, a health-related quality of life survey, were also administered before and 1 month after introducing the beds.

Results

Blood pressure measurements, TUG test results, and questionnaire survey scores improved significantly 1 month after the introduction of the beds. Also, evacuees with higher blood D-dimer values tended to show improvement, suggesting that the beds may have had a good effect on persons with underlying venous thrombotic disorders.

Conclusion

Makeshift beds of cardboard could be very useful in disaster shelters. (Disaster Med Public Health Preparedness. 2013;7:573–577)

»Point-of-Care« D-Dimer Testing

D-dimer testing is efficient in the exclusion of venous thromboembolism (VTE). D-dimer laboratory assays are predominantly performed in centralised laboratories in intra-hospital settings although most patients with suspected VTE are presented in primary care. On the other hand decreasing turnaround time for laboratory testing may significantly improve efficacy in emergency departments. Therefore an introduction of a rapid, easy to perform point of care (POC) assay for the identification of D-dimer may offer improvement in diagnostics flow of VTE both in primary care and emergency departments while it could also improve our diagnostic possibilities in some other severe clinical conditions (e.g. disseminated intra-vascular coagulation (DIC) and aortic aneurism (AA)) associated with increased D-dimer. Several POC D-dimer assays have been evaluated and majority of them have met the criteria for rapid and safe exclusion of VTE. In our hands three assays (Stratus, Pathfast and Cardiac) have the laboratory performance profile comparable with our routine D-dimer laboratory assay (Tinaqaunt).

Predictive value of D-dimer for portal vein thrombosis after portal hypertension surgery in hepatitis B virus-related cirrhosis

AIM

To evaluate the predictive value of D-dimer as a predictive indicator of portal vein thrombosis (PVT) after portal hypertension surgery in hepatitis B virus-related cirrhosis.

METHODS

A prospective study was carried out in 52 patients who had undergone surgery for portal hypertension in hepatitis B virus-related cirrhosis. Changes in perioperative dynamic D-dimer were observed. The sensitivity, specificity, positive predictive values and negative predictive values of D-dimer were calculated, and ROC curves were analyzed.

RESULTS

The D-dimer levels in the group developing postoperative PVT was significantly higher than those in the group not developing PVT (P = 0.001), and the ROC semiquantitative and qualitative analysis of D-dimer showed a moderate predictive value in PVT (semi-quantitative value Az = 0.794, P = 0.000; qualitative analysis: Az = 0.739, P = 0.001).

CONCLUSION

Dynamic monitoring of D-dimer levels in patients with portal hypertension after surgery can help early diagnosis of PVT, as in cases where the D-dimer levels steadily increase and exceed 16 microg/mL, the possibility of PVT is very high.

Predictive value of D-dimer for portal vein thrombosis after portal hypertension surgery in hepatitis B virus-related cirrhosis

AIM: To evaluate the predictive value of D-dimer as a predictive indicator of portal vein thrombosis (PVT) after portal hypertension surgery in hepatitis B virus-related cirrhosis.

METHODS: A prospective study was carried out in 52 patients who had undergone surgery for portal hypertension in hepatitis B virus-related cirrhosis. Changes in perioperative dynamic D-dimer were observed. The sensitivity, specificity, positive predictive values and negative predictive values of D-dimer were calculated, and ROC curves were analyzed.

RESULTS: The D-dimer levels in the group developing postoperative PVT was significantly higher than those in the group not developing PVT (P = 0.001), and the ROC semi-quantitative and qualitative analysis of D-dimer showed a moderate predictive value in PVT (semi-quantitative value Az = 0.794, P = 0.000; qualitative analysis: Az = 0.739, P = 0.001).

CONCLUSION: Dynamic monitoring of D-dimer levels in patients with portal hypertension after surgery can help early diagnosis of PVT, as in cases where the D-dimer levels steadily increase and exceed 16 μg/mL, the possibility of PVT is very high.

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

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

Sensitive and quantitative, 10-min immunofluorometric assay for D-Dimer in whole blood

INTRODUCTION

Normal concentrations of D-Dimer can be used to exclude venous thromboembolism (VTE). However, methods for sensitive and quantitative D-Dimer measurements at the point-of-care (POC) are still limited.

MATERIALS AND METHODS

We developed a 10-min, non-competitive immunofluorometric assay for D-Dimer in citrated whole blood and plasma using pre-dispensed reagents dried in single assay wells. The simple, automated assay procedure comprises a 1:50 sample dilution, one-step incubation, washing, and time-resolved fluorometric measurement directly from the wet well surface.

RESULTS

The limits of detection (background + 3SD) and quantification (CV <15%) were 0.05 and 0.2 mg/L D-Dimer, respectively, and the assay was linear up to 400 mg/L. Correlations to Roche TinaQuant (r=0.726, n=200) and Biopool Auto.Dimer (r=0.190, n=149) were carried out using citrated plasma. Diagnostic sensitivity, specificity, and negative (NPV) and positive (PPV) predictive values were 98.7%, 64.4%, 99.1% and 55.1%, and 92.2%, 81.0%, 95.9% and 68.3%, respectively, using cut-off values of 0.6 and 1.0 mg/L, respectively, in outpatients with deep vein thrombosis (DVT) and/or pulmonary embolism (PE) (n=77) compared with outpatients with various other diseases (n=174). The within- and between-run CVs near the cut-off values were < or =10% in both whole blood and plasma. The 95th percentile upper range in apparently healthy individuals was 0.68 mg/L of whole blood (n=101).

CONCLUSIONS

The high sensitivity and NPV suggest that the rapid immunofluorometric assay could be valuable for rapid exclusion of VTE in outpatients. With appropriate cut-offs, the assay could potentially be used as a stand-alone test or combined with clinical probability assessment, but further studies are required.

Point-of-Care Testing and Cardiac Biomarkers: The Standard of Care and Vision for Chest Pain Centers

Point-of-care testing (POCT) is defined as testing at or near the site of patient care. POCTdecreases therapeutic turnaround time (TTAT), increases clinical efficiency, and improves medical and economic outcomes. TTAT represents the time from test ordering to patient treatment. POC technologies have become ubiquitous in the United States, and, therefore,so has the potential for speed, convenience, and satisfaction, strong advantages for physicians, nurses, and patients in chest pain centers. POCT is applied most beneficially through the collaborative teamwork of clinicians and laboratorians who use integrative strategies, performance maps, clinical algorithms, and care paths (critical pathways). For example, clinical investigators have shown that on-site integration of testing for cardiac injury markers (myoglobin, creatinine kinase myocardial band [CKMB],and cardiac troponin I [cTnI]) in accelerated diagnostic algorithms produces effective screening, less hospitalization, and substantial savings. Chest pain centers, which now total over 150 accredited in the United States, incorporate similar types of protocol-driven performance enhancements. This optimization allows chest pain centers to improve patient evaluation, treatment, survival, and discharge. This article focuses on cardiac biomarker POCT for chest pain centers and emergency medicine.

Risk stratification of chest pain patients by point-of-care cardiac troponin T and myoglobin measured in the emergency department

A prospective multicenter study including 1410 chest pain patients with suspected acute coronary syndromes was carried out to examine the predictive value of biological cardiac markers for adverse events measured by a point-of-care system. Admission cardiac troponin T (cTnT) and myoglobin were measured in parallel on a point-of-care system in the emergency department and -- together with CK-MB mass -- on lab analyzers. In a one-year follow-up, cardiac and non-cardiac death, acute myocardial infarction, unstable angina pectoris and need for revascularization were registered. Median time between onset of symptoms and admission was 285 min; 172 patients (12.2%) had no event during follow-up. If the cTnT, measured either by the point-of-care system or a conventional lab analyzer, was >0.05 microg/L, then the chance of a cardiac event during the follow-up period was doubled (18% vs. 9%). Serial cTnT measurement did not add any further value to the predictive power of the admission cTnT. Myoglobin and CK-MB mass identified increasing risk with increasing concentration quartiles; cardiac event rates were 2.8- to 4.4-fold higher between the quartiles with the lowest and those with the highest analyte concentration, respectively. There was no difference in non-cardiac death rates between any concentration quartiles. In conclusion, the prediction of clinical events by cardiac troponin T and myoglobin measured with a point-of-care analyzer in the emergency department was as good as that of the same cardiac markers and CK-MB mass measured on lab analyzers.

The performance of quantitative D-dimer assays in laboratory routine

Assessment of D-dimer in plasma is routinely used for the exclusion of venous thrombosis and the monitoring of hypercoagulability. Little information is available about the performance of D-dimer assays in clinical laboratories examined by external quality assessment schemes. We obtained results from 423 laboratories measuring plasma pools from patients with elevated D-dimer levels mixed with human normal plasma. The results from five samples were reported containing D-dimer from the lower normal range up to a 20-fold increased level. In addition, information about the assignment of a cut-off point and the medical need to apply these assays was obtained by standardized questionnaire. Participants reported results and additional information from 20 different assays. Lack of standardization regarding the calibration concepts obstructs comparability of results. Results in one sample varied up to 20-fold between the assays applied. In addition, a high variability was reported around the cut-off values introduced for the exclusion of venous thrombosis and pulmonary embolism. As a consequence, generally accepted cut-off values cannot be established. For cut-off assignment, 62% of participants used the kit insert but also 14% used local validation. In conclusion, standardization or at least harmonization of D-dimer assays is necessary to ensure comparability of D-dimer plasma levels measured in clinical routine.

The predictive characteristics of D-dimer testing in outpatients with suspected venous thromboembolism: a Bayesian approach

BACKGROUND

Despite the widespread use of quantitative methods to measure D-dimer, clinical decisions commonly are based only on binary test information (positive/negative). This study aimed to determine the significance of quantitative D-dimer results in the evaluation of venous thromboembolism (VTE) by means of a differentiated Bayesian approach.

METHODS

Prospective study in 118 outpatients referred for workup of suspected pulmonary embolism (n = 75) or deep vein thrombosis (n = 43). The sensitivity and specificity of D-dimer results obtained by DD VIDAS (Biomerieux, France), STA Liatest (Diagnostica Stago, France), and D-dimer plus (Dade, US) were assessed for five different cut-offs. Further, predictive values and multilevel likelihood ratios were calculated in order to assess the operative test characteristics in excluding or confirming VTE.

RESULTS

At a cut-off of 500 ng/ml and pretest probabilities < 47%, the VIDAS provides a negative predictive value (NPV) > 95%, whereas a positive predictive value (PPV) > 95% is obtained in patients with a D-dimer > 10,000 ng/ml and pretest probabilities > 50%. At a cut-off of 500 ng/ml and pretest probabilities < 33%, the Liatest exhibits a NPV > 95%, whereas a PPV > 95% is obtained in patients with a D-dimer >10,000 ng/ml and pretest probabilities > 37%. Finally, with the D-dimer plus, a NPV > 95% is seen at a cut-off of 150 ng/ml and pretest probabilities < 30%, whereas a PPV > 95% is obtained at a cut-off > 1000 ng/ml and pretest probabilities > 67%.

CONCLUSIONS

D-dimer measurements in outpatients cannot only allow for exclusion but, in some situations, also for confirmation of venous thromboembolism. It is therefore advisable to conduct a quantitative interpretation of D-dimer results.

A Rapid Bedside D-Dimer Assay (Cardiac D-Dimer) for Screening of Clinically Suspected Acute Aortic Dissection

BACKGROUND

A rapid laboratory test for diagnosis of acute aortic dissection (AAD) has not been available. We performed this prospective study to determine the utility of a rapid bedside D-dimer (DD) assay for detection of AAD.

METHODS AND RESULTS

Patients with suspected AAD were recruited and their DD levels were measured by rapid bedside assay. They were divided into 2 groups according to enhanced computed tomography findings: an AAD group (n = 30) and a non-AAD group (n = 48). The median DD level was higher in the AAD group (1.80 microg/ml) than in the non-AAD group (0.42 microg/ml) (p = 0.000). The rapid bedside DD assay showed 100% sensitivity, 54% specificity, 58% positive predictive value and 100% negative predictive value for detection of AAD with a normal DD level of up to 0.5 microg/ml. The combination of DD level >0.5 microg/ml and systolic blood pressure > or = 180 mmHg showed 86% positive predictive value for detection of AAD. Conclusions We conclude that the rapid bedside DD assay is a highly sensitive method for early exclusion of AAD in patients with chest and/or back pain suggestive of AAD. Acute aortic dissection is highly probable if a rapid DD assay shows the elevated DD level with systolic blood pressure > or = 180 mmHg on admission.

A new rapid bedside assay for quantitative testing of D-Dimer (Cardiac D-Dimer) in the diagnostic work-up for deep vein thrombosis

The accuracy of a new bedside, rapid and quantitative D-Dimer assay (Cardiac D-Dimer) was evaluated in outpatients with clinically suspected deep vein thrombosis (DVT); VIDAS test was used as reference method. Eighty consecutive outpatients with suspected DVT of a lower limb were included in the study. Patients were classified as DVT positive or negative according to results of objective test (serial CUS), pretest clinical probability and 3-month follow-up. DVT was diagnosed in 32/80 patients (40%). The performance of the two D-Dimer assays was comparable, as indicated by the areas under the ROC curves (0.89 and 0.88, for Cardiac D-Dimer and VIDAS, respectively) and the coefficient of correlation (r=0.91). The reproducibility of the test was acceptable (from 6.2% to 12.0%). The sensitivity and negative predictive values were 100% for both tests. The specificity (SP) and positive predictive values (PPV) were similar (SP: 50.0% and 52.0%, PPV: 57.1% and 58.2%, for Cardiac D-Dimer and VIDAS, respectively). The Cardiac D-Dimer test proved to be very accurate and produced results fully comparable to those obtained with the VIDAS test. Since the test can be directly performed in the emergency room within a few minutes, it seems to have great clinical potential. The place of this assay in the diagnostic strategy of DVT remains to be determined in prospective management studies.

A new rapid point-of-care D-dimer enzyme-linked immunosorbent assay (Stratus CS D-dimer) for the exclusion of venous thromboembolism

To evaluate the performances of a new D-dimer assay, Stratus CS D-dimer (Dade Behring, Newark, Delaware, USA), for the exclusion of venous thromboembolism and to determine the best cut-off values. This test relies on a sandwich enzyme-linked immunosorbent assay with a fluorogenic substrate in a radial partition immunoassay system in a dedicated device. It does not require laboratory staff and the results are available within 18 min. Two hundred and ninety-one frozen samples from patients suspected of either deep venous thrombosis (n = 137) or pulmonary embolism (n = 154) were measured and the results compared with the VIDAS D-dimer New assay. There were 37 deep venous thrombosis (27%) and 49 pulmonary embolism (32%) samples. Receiver-operating characteristic curve analysis indicated that the cut-off value could be set at either 300 or 400 ng/ml Fibrinogen Equivalent Units (FEU). The coefficient of variation determined with a lyophilized low-level control plasma (305 ng/ml FEU) was 6%. With a cut-off at 300 ng/ml FEU, the sensitivity, the specificity and the negative predictive value were 100% [95% confidence interval (CI), 95.8-100], 33.1% (95% CI, 26.8-40) and 100% (95% CI, 94.7-100), respectively. Raising the cut-off to 400 ng/ml FEU, the corresponding figures were 96.5% (95% CI, 90.1-99.3), 46.3% (95% CI, 39.4-53.2) and 96.9% (95% CI, 91.3-99.4), respectively. At 400 ng/ml, three results were false-negative, one with both devices and two with the Stratus D-dimer only. Stratus D-dimer appears to be suitable for the exclusion of venous thromboembolism in the emergency room setting.

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

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

Evaluation of advanced D-dimer assay for the exclusion of venous thromboembolism

The performances for thromboembolic disease exclusion of a new microlatex-enhanced D-dimer immunoassay have been evaluated. Advanced D-dimer (Dade-Behring, Marburg, Germany) was tested with two automated analyzers, namely BCS and CA-1500. Precision studies yielded coefficients of variation (within-run and run-to-run) of 3% and 6.3% at D-dimer levels near the cut-off value, for BCS and CA-1500 respectively. Frozen samples from 294 consecutive symptomatic outpatients suspected of either deep venous thrombosis (140) or pulmonary embolism (154) from a previous management study were tested with both analyzers, as well as with the VIDAS New assay (BioMerieux, Marcy-l'Etoile, France). For BCS, sensitivity and specificity were 96.6% (95% CI, 90.5, 99.3) and 42% (35.1, 49.0) respectively at a cut-off value of 1.35 microg/ml. For CA-1500, the corresponding figures were 95.5% (88.9, 98.8) and 47.8% (40.8, 54.9) at a cutt-off value of 1.1 microg/ml. This assay appears promising and should be validated in clinical practise to assess its place in the work-up schemes of thromboembolism.

Trends in miniaturized total analysis systems for point-of-care testing in clinical chemistry

A currently emerging approach enables more widespread monitoring of health parameters in disease prevention and biomarker monitoring. Miniaturisation provides the means for the production of small, fast and easy-to-operate devices for reduced-cost healthcare testing at the point-of-care (POC) or even for household use. A critical overview is given on the present state and requirements of POC testing, on microTAS elements suited for implementation in future microTAS devices for POC testing and microTAS systems for the determination of clinical parameters.