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.     

Pleural ELFA D-dimer assay: a surrogate marker for malignant pleural effusion

Background

Malignant pleural effusion is associated with enhanced fibrinolysis. However, no data are available concerning the precise role of pleural D-dimer assay in pleural effusion. We therefore assessed the role of pleural D-dimer assay in predicting malignant pleural effusion.

Patients and Methods

A prospective laboratory investigation was conducted in a tertiary care teaching hospital. The study included consecutive patients with pleural effusion who presented at the Pulmonary Department between November 2009 and May 2010. Blood and pleural D-dimer levels were measured by Enzyme Linked Fluorescent assay (ELFA). The results were correlated with the clinical, laboratory, and radiological findings, and with the final diagnosis of the pleural fluid.

Results

A total of 103 patients with pleural effusion were included in the study. The Pleural ELFA D-dimer results were found to be positively correlated with pleural etiology of malignancy (p = 0.0001). Pleural etiology was also correlated with pleural LDH, pleural protein, pleural PH, pleural glucose, pleural and blood CRP, but not with ADA. In a binary logistic regression, only the pleural ELFA D-dimer assay was a significant predictor of the malignant pleural effusion (odds ratio 1.007; 95% confidence interval 1.002-1.012; p = 0.007). The area under the receiver operating characteristics curve for malignancy was 0.79. A D-dimer level of 146 mg/ml had a sensitivity of 82% and a specificity of 74%.

Conclusions

We found high D-dimer levels among malignant pleural effusion. D-dimer might be useful as a simple, noninvasive, surrogate marker for malignant pleural effusion.     

Clinical probability assessment and D-dimer determination in patients with suspected deep vein thrombosis, a prospective multicenter management study

Objectives

To investigate the reliability of a combined strategy of clinical assessment score followed by a local D-dimer test to exclude deep vein thrombosis. For comparison D-dimer was analysed post hoc and batchwise at a coagulation laboratory.

Design

Prospective multicenter management study.

Setting

Seven hospitals in southern Sweden.

Subjects

357 patients with a suspected first episode of deep vein thrombosis (DVT) were prospectively recruited and pre-test probability score (Wells score) was estimated by the emergency physician. If categorized as low pre-test probability, D-dimer was analysed and if negative, DVT was considered to be ruled out. The primary outcome was recurrent venous thromboembolism (VTE) during 3 months of follow up.

Results

Prevalence of DVT was 23.5% (84/357). A low pre-test probability and a negative D-dimer result at inclusion was found in 31% (110/357) of the patients of whom one (0.9%, [95% CI 0.02-4.96]) had a VTE at follow up. Sensitivity, specificity, negative predictive value and negative likelihood ratio for our local D-dimer test in the low probability group were 85.7%, 74.5%, 98.2%, and 0,19 respectively compared to 85.6%, 67,6%, 97.9% and 0,23 using batchwise analysis at a coagulation laboratory.

Conclusion

Pre-test probability score and D-dimer safely rule out DVT in about 30% of outpatients with a suspected first episode of DVT. One out of 110 patients was diagnosed with DVT during follow up. No significant difference in diagnostic performance was seen between local D-dimer test and the post hoc batch analysis with the same reagent in the low probability group.     

Safety of excluding acute pulmonary embolism based on an unlikely clinical probability by the Wells rule and normal D-dimer concentration: A meta-analysis

Introduction

The Wells clinical decision rule (CDR) and D-dimer tests can be used to exclude pulmonary embolism (PE). We performed a meta-analysis to determine the negative predictive value (NPV) of an “unlikely” CDR (≤ 4 points) combined with a normal D-dimer test and the safety of withholding anti-coagulants based on these criteria.

Methods

Prospective studies that withheld anti-coagulant treatment from patients with clinically suspected PE and an “unlikely” CDR in combination with a normal D-dimer concentration without performing further tests were searched for in Medline, Cochrane and Embase. Primary endpoints were the recurrence rate of venous thromboembolism (VTE) and PE-related mortality during 3-months follow-up.

Results

Four studies including 1660 consecutive patients were identified. The pooled incidence of VTE after initial exclusion of acute PE based on an “unlikely” CDR and normal D-dimer was 0.34% (95%CI 0.036-0.96%), resulting in a NPV of 99.7% (95%CI: 99.0-99.9%, random effects-model). The risk for PE related mortality was very low: 1/1660 patients had fatal PE (0.06%, 95%CI 0.0017-0.46%).

Conclusion

Acute PE can be safely excluded in patients with clinically suspected acute PE who have an “unlikely” probability and a negative D-dimer test and anticoagulant treatment can be withheld. There is no need for additional radiological tests in these patients to rule out PE.     

Multicenter evaluation of a new quantitative highly sensitive D-dimer assay, the Hemosil® D-dimer HS 500, in patients with clinically suspected venous thromboembolism

Introduction

D-dimer testing is widely used in conjunction with clinical pretest probability (PTP) for venous thromboembolism (VTE) exclusion. We report on a multicenter evaluation of a new, automated, latex enhanced turbidimetric immunoassay [HemosIL® D-Dimer HS 500, Instrumentation Laboratory (IL)].

Materials and Methods

747 consecutive outpatients with suspected proximal deep vein thrombosis (DVT, n = 401) or pulmonary embolism (PE, n = 346) were evaluated at four university hospitals in a management study with a 3 month follow-up. Samples were tested at each center using the new D-dimer assay on an automated coagulation analyzer [ACL TOP (IL)], with clinical cut-off for VTE at 500 ng/mL (FEU).

Results

The sensitivity and negative predictive value (NPV) were 100% for all PTP subgroups (no false negative results); for both sensitivity and NPV the lower limit of the 95% CI in patients with moderate/low PTP was higher than 95%. The overall specificity was 45.1% (95%CI: 41.1-49.3%). Higher specificity value was recorded in the low PTP subgroup [49.2% (95%CI: 41.7-56.7)]. No significant differences were found between patients suspected of having DVT or PE; sensitivity and NPV were 100%. The reproducibility of the assay was good, being the total CVs% less than 10% for D-dimer concentration near the clinical cut-off.

Conclusions

The new, highly sensitive D-dimer assay proved to be accurate when used for VTE diagnostic work-up in outpatients. Based on 100% sensitivity and NPV and lower limit of the 95% CI higher than 95%, the assay can be used as a stand-alone test in patients with non high PTP.     

Diagnosis and management of venous thromboembolism: Results of a survey on current clinical practice

Background

The implementation of evidence from clinical studies into daily clinical practice is not a straightforward process. We developed a standardized questionnaire to explore clinical practice patterns in the management of VTE, in particular about the use of pre-clinical probability and D-dimer testing and on the home treatment of pulmonary embolism (PE).

Methods

The standardized questionnaire was sent to all 394 physician members of the Italian Society of Thrombosis and Haemostasis (SISET) by e-mail. The questionnaire contained three groups of questions: about general information, about the diagnostic process for both deep venous thrombosis (DVT) and PE, and about home-therapy of PE.

Results

One hundred and twenty-eight (32.5%) physicians responded the questionnaire. For DVT diagnosis 69 (54.3%) physicians answered that they always use the D-dimer test; 4 (3.1%) do never use it; whereas only 11 (8.7%) take notice of the D-dimer result before visiting the patients; 38 (29.9%) use only clinical judgment to assess pre-clinical probability of disease. For the diagnosis of PE 80 (66.1%) physicians always use the D-dimer test, whereas 3 (2.5%) do never use it; whereas 14 (11.7%) take notice of the D-dimer result before visiting the patients; 50 (41.3%) use only clinical judgment to assess pre-clinical probability. Sixty-six (59.5%) clinicians declared to treat patients with PE at home, when feasible.

Conclusion

The diagnostic approach to VTE among expert physicians appears to be heterogeneous; in particular there is no widespread use of clinical prediction rules. The majority of expert physicians appear to consider the possibility of treating at home patients with PE.     

A Cost-effectiveness Analysis of Diagnostic Algorithms of Deep Vein Thrombosis at the Emergency Department

Introduction

Suspected cases of deep vein thrombosis are common at emergency departments and they often require extensive and costly diagnostic testing. The objective of this study was to evaluate whether a diagnostic algorithm based upon pre-test probability and D-dimer in diagnosing deep vein thrombosis may be cost-effective from a societal perspective in a Swedish setting.

Material and Methods

The cost-effectiveness of two alternative diagnostic algorithms were calculated using decision analysis. An algorithm which out ruled deep vein thrombosis among low probability patients with negative D-dimer was compared to a traditional algorithm including compression ultrasonography and/or contrast venography for all patients. For sensitivity analysis, a third reversed algorithm, where D-dimer was followed by pre-test probability, was analyzed. Estimates of probabilities were obtained from a prospective management study, including 357 outpatients with clinical suspicion of deep vein thrombosis. Direct costs were estimated using prices from Scania, Sweden. Indirect costs were estimated using time spent at the local emergency department and gross average wages in Sweden.

Results

The total cost of the pre-test probability and D-dimer algorithm was estimated to €406 per patient and the traditional algorithm was estimated to €581 per patient. Reversing the order of the score and test resulted in an estimate of €421 per patient.

Conclusion

At no significant difference in diagnostic efficacy the algorithm based upon pre-test probability and D-dimer was cost-effective, while the reversed algorithm and diagnostic imaging for all patients were not.     

Comparison of the clinical usefulness of two quantitative D-Dimer tests in patients with a low clinical probability of pulmonary embolism

Background

Quantitative D-Dimer tests are established methods in the non-invasive diagnostic management to rule out venous thromboembolism (VTE). The diagnostic performance and the clinical efficiency different D-Dimer assays in the exclusion of pulmonary embolism (PE) have not yet been compared in a clinical outcome study.

Objective

Evaluation of the efficiency and safety of excluding the diagnosis of PE with two different quantitative D-Dimer assays in consecutive patients with clinically suspected PE.

Patients and Methods

We studied the VTE-failure rate of 2206 consecutive patients with an unlikely clinical probability in whom VIDAS or Tinaquant D-Dimer tests were performed.

Results

The prevalence of PE in 1238 patients whose D-Dimer level was analyzed with Tinaquant assay was 11%. The VIDAS assay group consisted of 968 patients with a PE prevalence of 13%. The VIDAS assay had a sensitivity of 99.2% (95%CI; 96- > 99.9%), the Tinaquant assay of 97.3% (95%CI; 93 -99%). The negative predictive value (NPV) in the Tinaquant assay group was 99.4% (95%CI 98-99.8%) in comparison to 99.7% (95%CI 99-> 99.9%) in the VIDAS assay group. During 3 month of follow-up, there were no fatal cases of PE among patients with normal D-Dimer and unlikely clinical probability in both D-Dimer assay groups. In addition, the test efficiency of Tinaquant assay was significantly higher in comparison to VIDAS assay (52% vs 42%, p < 0.001).

Conclusion

Both Tinaquant and VIDAS D-Dimer tests perform equally well in combination with an unlikely clinical probability in excluding PE. The Tinaquant test was shown to be more efficient.     

A higher d-dimer threshold safely rules-out pulmonary embolism in very elderly emergency department patients

Introduction

D-dimer is commonly used in the workup of suspected Pulmonary Embolism (PE), but its specificity decreases with age. We evaluated whether using a higher cutoff value for D-dimer could increase the test specificity without reducing its sensitivity for ruling-out PE in elderly and very elderly patients presenting to the Emergency Department (ED).

Material and Methods

All patients with D-dimer and pulmonary Computed Tomography Angiography (CTA) performed in the ED of Vimercate Hospital, from 2010 through 2012 for clinical suspicion of PE were included in this retrospective cohort study.

Results

Study population 481 patients (63.4% women, mean age 73.0 ± 16.1 years, confirmed PE 22.5%). In very elderly patients (aged 80 or more years, n = 191), compared with standard 490 ng/mL D-dimer threshold, both higher fixed (1000 ng/mL) and age-adjusted cutoffs increase the specificity of D-dimer for the exclusion of PE maintaining a Negative Predictive Value of 100%. Potentially avoided CTAs were 12(6.3%) using 1000 ng/mL cutoff and 10(5.2%) age-adjusted. In very elderly patients the Number Needed to Test was incalculable for the standard cutoff (0 cases), 16 for 1000 ng/mL and 19 for age-adjusted. In patients with PE, index episode mortality was 6.5%, and death occurred only in subjects with D-dimer values above 1000 ng/mL and age-adjusted thresholds.

Conclusion

For very elderly patients with suspected PE in ED, both higher fixed D-dimer (1000 ng/mL) and age-adjusted thresholds increase test specificity for excluding PE without reducing its sensitivity, leading to a safe reduction in the number of CTAs.