HemosIL D-dimer HS assay in the diagnosis of deep vein thrombosis and pulmonary embolism. Results of a multicenter management study

The DAGMAR Score: D-dimer assay-guided moderation of adjusted risk. Improving specificity of the D-dimer for pulmonary embolism

We generated a novel scoring system to improve the test characteristics of D-dimer in patients with suspected PE (pulmonary emboli). Electronic Medical Record data were retrospectively reviewed on Emergency Department (ED) patients 18 years or older for whom a D-dimer and imaging were ordered between June 4, 2012 and March 30, 2016. Symptoms (dyspnea, unilateral leg swelling, hemoptysis), age, vital signs, medical history (cancer, recent surgery, medications, history of deep vein thrombosis or PE, COPD, smoking), laboratory values (quantitative D-dimer, platelets, and mean platelet volume (MPV)), and imaging results (CT, VQ) were collected. Points were designated to factors that were significant in two multiple regression analyses, for PE or positive D-dimer. Points predictive of PE were designated positive values and points predictive of positive D-dimer, irrespective of presence of PE, were designated negative values. The DAGMAR (D-dimer Assay-Guided Moderation of Adjusted Risk) score was developed using age and platelet adjustment and points for factors associated with PE and elevated D-dimer. Of 8486 visits reviewed, 3523 were unique visits with imaging, yielding 2253 (26.5%) positive D-dimers. 3501 CT scans and 156 VQ scans were completed, detecting 198 PE. In our cohort, a DAGMAR Score < 2 equated to overall PE risk < 1.2%. Specificity improved (38% to 59%) without compromising sensitivity (94% to 96%). Use of the DAGMAR Score would have reduced CT scans from 2253 to 1556 and lead to fewer false negative results. By considering factors that affect D-dimer and also PE, we improved specificity without compromising sensitivity.

Age-adjusted cut-off using the IL D-dimer HS assay to exclude pulmonary embolism in patients presenting to emergency

BACKGROUND/AIM

The ADJUST-PE study showed that an age-adjusted D-dimer (AADD) (age years × 10 ng/mL if >50 years) combined with an unlikely pre-test probability (PTP) can increase the proportion of older patients in whom pulmonary embolism (PE) can be safely excluded, but the IL D-dimer HS assay was not assessed. To assess the ability of the IL D-dimer HS assay to exclude PE using the AADD.

METHODS

Retrospective analysis of consecutive patients presenting with symptoms of acute PE to one of three Monash Health Emergency Departments (January 2013-January 2014) who had computed tomography pulmonary angiography. In the group with D-dimer, efficiency (proportion of PE excluded based on a combination of unlikely PTP and negative D-dimer) was determined using (i) current laboratory (200 ng/mL), (ii) conventional (230 ng/mL) and (iii) modified (375 ng/mL if age ≥60 years) AADD cut-offs.

RESULTS

A total of 176 patients with D-dimers was included (mean age = 58.5 years; 54.0% males; 71.0% age >50 years). Prevalence of PE in the overall, unlikely and likely PTP groups, was 17.0, 13.0 and 24.6% respectively. In the unlikely PTP group (115 patients), efficiency for the current, conventional, modified and AADD cut-offs was 9.6, 24.3, 30.4 and 37.4% respectively.

CONCLUSION

The absolute increase in efficiency of an AADD compared to conventional cut-off using the IL D-dimer HS assay is modest (~10%) and requires prospective validation. Modifying our cut-off to 230 ng/mL and systematic implementation of a clinical algorithm, including D-dimer testing and PTP, is likely a more important first step.

Use of the d-dimer for Detecting Pulmonary Embolism in the Emergency Department

BACKGROUND

Assessment for pulmonary embolism (PE) in the emergency department (ED) remains complex, involving clinical decision tools, blood tests, and imaging.

OBJECTIVE

Our objective was to examine the test characteristics of the high-sensitivity d-dimer for the diagnosis of PE at our institution and evaluate use of the d-dimer and factors associated with a falsely elevated d-dimer.

METHODS

We retrospectively collected data on adult patients evaluated with a d-dimer and computed tomography (CT) pulmonary angiogram or ventilation perfusion scan at two EDs between June 4, 2012 and March 30, 2016. We collected symptoms (dyspnea, unilateral leg swelling, hemoptysis), vital signs, and medical and social history (cancer, recent surgery, medications, history of deep vein thrombosis or PE, chronic obstructive pulmonary disease, smoking). We calculated test characteristics, including sensitivity, specificity, and likelihood ratios for the assay using conventional threshold and with age adjustment, and performed a univariate analysis.

RESULTS

We found 3523 unique visits with d-dimer and imaging, detecting 198 PE. Imaging was pursued on 1270 patients with negative d-dimers, revealing 9 false negatives, and d-dimer was sent on 596 patients for whom negative Pulmonary Embolism Rule-Out Criteria (PERC) were documented with 2% subsequent radiographic detection of PE. The d-dimer showed a sensitivity of 95.7% (95% confidence interval [CI] 91-98%), specificity of 40.0% (95% CI 38-42%), negative likelihood ratio of 0.11 (95% CI 0.06-0.21), and positive likelihood ratio of 1.59 (95% CI 1.53-1.66) for the radiographic detection of PE. With age adjustment, 347 of the 2253 CT scans that were pursued in patients older than 50 years with an elevated d-dimer could have been avoided without missing any additional PE. Many risk factors, such as age, history of PE, recent surgery, shortness of breath, tachycardia and hypoxia, elevated the d-dimer, regardless of the presence of PE.

CONCLUSIONS

Many patients with negative d-dimer and PERC still received imaging. Our data support the use of age adjustment, and perhaps adjustment for other factors seen in patients evaluated for PE.

Validation of STA-Liatest D-Di assay for exclusion of pulmonary embolism according to the latest Clinical and Laboratory Standard Institute/Food and Drug Administration guideline. Results of a multicenter management study

Combined clinical pretest probability (PTP) and D-dimer testing have great diagnostic value for pulmonary embolism exclusion. To harmonize performance levels of D-dimer assays available on the market, the Clinical and Laboratory Standard Institute (CLSI) has published a guideline, endorsed by the US Food and Drug Administration (FDA). Such guideline specifies the ideal D-dimer assay characteristic and target population. This study was conducted following the CLSI guideline to upgrade the assay-intended use and obtain FDA clearance of STA-Liatest D-Di assay for pulmonary embolism exclusion in patient with low/moderate PTP. This was an international, multicenter, prospective nonrandomized, noninterventional clinical outcome management study conducted in a standard of care setting. D-dimer assay was performed in consecutive, ambulatory outpatients suspected of pulmonary embolism, with low/moderate PTP, and without medical conditions or in clinical settings known to alter default D-dimer values regardless of the presence of thrombosis using a threshold of 0.5 μg/ml (fibrinogen equivalent units) for venous thromboembolism exclusion. Results were used to determine test performance. Of 1141 patients who underwent D-dimer testing, 1060 had valid results and completed study as planned. STA-Liatest D-Di assay performance has exceeded the CLSI/FDA guidance requirements, with a sensitivity of 97.6% (95% confidence interval: 91.7–99.7%) and a negative predictive value of 99.7% (95% confidence interval: 99.0–100%). STA-Liatest D-Di assay has an excellent performance when used in combination with a PTP score in relevant patients and has the potential to minimize the economic healthcare burden avoiding unnecessary and expensive imaging tests.

D-dimer test for excluding the diagnosis of pulmonary embolism

BACKGROUND

Pulmonary embolism (PE) can occur when a thrombus (blood clot) travels through the veins and lodges in the arteries of the lungs, producing an obstruction. People who are thought to be at risk include those with cancer, people who have had a recent surgical procedure or have experienced long periods of immobilisation and women who are pregnant. The clinical presentation can vary, but unexplained respiratory symptoms such as difficulty breathing, chest pain and an increased respiratory rate are common.D-dimers are fragments of protein released into the circulation when a blood clot breaks down as a result of normal body processes or with use of prescribed fibrinolytic medication. The D-dimer test is a laboratory assay currently used to rule out the presence of high D-dimer plasma levels and, by association, venous thromboembolism (VTE). D-dimer tests are rapid, simple and inexpensive and can prevent the high costs associated with expensive diagnostic tests.

OBJECTIVES

To investigate the ability of the D-dimer test to rule out a diagnosis of acute PE in patients treated in hospital outpatient and accident and emergency (A&E) settings who have had a pre-test probability (PTP) of PE determined according to a clinical prediction rule (CPR), by estimating the accuracy of the test according to estimates of sensitivity and specificity. The review focuses on those patients who are not already established on anticoagulation at the time of study recruitment.

SEARCH METHODS

We searched 13 databases from conception until December 2013. We cross-checked the reference lists of relevant studies.

SELECTION CRITERIA

Two review authors independently applied exclusion criteria to full papers and resolved disagreements by discussion.We included cross-sectional studies of D-dimer in which ventilation/perfusion (V/Q) scintigraphy, computerised tomography pulmonary angiography (CTPA), selective pulmonary angiography and magnetic resonance pulmonary angiography (MRPA) were used as the reference standard.•

PARTICIPANTS

Adults who were managed in hospital outpatient and A&E settings and were suspected of acute PE were eligible for inclusion in the review if they had received a pre-test probability score based on a CPR.•

INDEX TESTS

quantitative, semi quantitative and qualitative D-dimer tests.• Target condition: acute symptomatic PE.• Reference standards: We included studies that used pulmonary angiography, V/Q scintigraphy, CTPA and MRPA as reference standard tests.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed quality using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). We resolved disagreements by discussion. Review authors extracted patient-level data when available to populate 2 × 2 contingency tables (true-positives (TPs), true-negatives (TNs), false-positives (FPs) and false-negatives (FNs)).

MAIN RESULTS

We included four studies in the review (n = 1585 patients). None of the studies were at high risk of bias in any of the QUADAS-2 domains, but some uncertainty surrounded the validity of studies in some domains for which the risk of bias was uncertain. D-dimer assays demonstrated high sensitivity in all four studies, but with high levels of false-positive results, especially among those over the age of 65 years. Estimates of sensitivity ranged from 80% to 100%, and estimates of specificity from 23% to 63%.

AUTHORS' CONCLUSIONS

A negative D-dimer test is valuable in ruling out PE in patients who present to the A&E setting with a low PTP. Evidence from one study suggests that this test may have less utility in older populations, but no empirical evidence was available to support an increase in the diagnostic threshold of interpretation of D-dimer results for those over the age of 65 years.

D-dimer: An Overview of Hemostasis and Fibrinolysis, Assays, and Clinical Applications

D-dimer is the smallest fibrinolysis-specific degradation product found in the circulation. The origins, assays, and clinical use of D-dimer will be addressed. Hemostasis (platelet and vascular function, coagulation, fibrinolysis, hemostasis) is briefly reviewed. D-dimer assays are reviewed. The D-dimer is very sensitive to intravascular thrombus and may be markedly elevated in disseminated intravascular coagulation, acute aortic dissection, and pulmonary embolus. Because of its exquisite sensitivity, negative tests are useful in the exclusion venous thromboembolism. Elevations occur in normal pregnancy, rising two- to fourfold by delivery. D-dimer also rises with age, limiting its use in those >80 years old. There is a variable rise in D-dimer in active malignancy and indicates increased thrombosis risk in active disease. Elevated D-dimer following anticoagulation for a thrombotic event indicates increased risk of recurrent thrombosis. These and other issues are addressed.

Changes in d-dimer levels in pregnant women according to gestational week

We performed a retrospective review of medical charts regarding blood d-dimer levels determined cross-sectionally by the latex agglutination assay in 1952 samples from 1185 women to determine changes in d-dimer levels according to the stage of pregnancy. Three of 17 women in whom further investigations were performed were found to have clinical venous thromboembolism (VTE). The median and 95th percentile values of d-dimer (μg/mL) in the 1182 women without clinical VTE, 0.54 and 2.41 at gestational week (GW) 4-13, increased gradually to 1.22 and 5.03 at GW 14-27, 1.81 and 6.18 at GW 28-35, and 2.13 and 5.85 at GW 36-42, respectively. A total of nine women (0.76%), including three women with clinical VTE, exhibited a d-dimer level >14.0μg/mL, which was well above the 99th percentile for any stage of pregnancy. Thus, 3 (33%) of the nine with a d-dimer level >14μg/mL developed clinical VTE, while none of the remaining 1176 women with a d-dimer level ⩽14μg/mL developed clinical VTE. Although further prospective studies are required, our results suggested that there is a certain cut-off d-dimer value that would allow us to differentiate between pregnant women with and without clinical VTE.

Prospective diagnostic accuracy assessment of the HemosIL HS D-dimer to exclude pulmonary embolism in emergency department patients

INTRODUCTION

Chest pain and shortness of breath are among the most common symptoms requiring immediate evaluation. Testing for pulmonary embolism (PE) has become easier and widespread due to D-dimer blood tests. Safe use of these tests is only possible if sensitivity is high and they are used in non-high probability patients. We evaluated diagnostic performance of the HemosIL HS D-dimer, which despite FDA approval in 2005, has been minimally reported in prospective standard clinical care.

MATERIALS AND METHODS

We used a prospective observational study design to follow patients in a single center with the HemosIL HS ordered for symptoms of possible PE with positive test result if >243 ng/ml. The outcome was PE or deep venous thrombosis (DVT) at the time of presentation or subsequent 45 days determined by structured evaluation of imaging tests, phone, or medical record follow-up in all patients.

RESULTS

529 patients received a D-dimer and 4.7% were ultimately diagnosed with PE or DVT. The sensitivity of the HemosIL HS was 96.0% (95% CI; 79.6 to 99.9%) specificity was 65.7% (95% CI; 61.4 to 69.8%) and likelihood ratio negative was 0.06 (95% CI; 0.01 to 0.42). The probability of PE in patients with a negative D-dimer was 1/332 or 0.3% (95% CI; 0.01% to 1.67%). The receiver operator curve had an area under the curve of 0.87 and supported the current cut-point as optimal.

CONCLUSIONS

The HemosIL HS D-dimer had high sensitivity, very low negative post-test probability and is useful in excluding PE in the acute care setting.