Diagnostic accuracy of thoracic paraspinal electromyography in amyotrophic lateral sclerosis.

The goal of this study was to estimate the accuracy of thoracic paraspinal (T-PSP) electromyography (EMG), performed at the time of initial evaluation, for the subsequent clinical diagnosis of amyotrophic lateral sclerosis (ALS). Medical records from a consecutive series of patients referred for suspected ALS were abstracted. Those in whom T-PSP EMG was not performed or for whom follow-up was not available were excluded. The study population included 64 patients. T-PSP EMG was abnormal in 28 (44%) study patients, 26 (93%) of whom were subsequently diagnosed with ALS. T-PSP EMG showed neither fibrillation potentials nor positive sharp waves in 36 (56%) patients, 9 (25%) of whom later developed ALS. The sensitivity of T-PSP for the diagnosis of ALS was 0.74 and the specificity was 0.93. The likelihood ratio positive was 10.5 and the likelihood ratio negative was 0.28. These results suggest that T-PSP EMG is very useful for "ruling in" the diagnosis of ALS, but less useful as a screening test for "ruling out" the diagnosis. Because T-PSP EMG is used clinically in an effort to confirm the diagnosis (and not as a screening test), these results suggest that T-PSP EMG is an extremely useful adjunct for the diagnosis of ALS.     

Diagnostic yield of noninvasive high spatial resolution electromyography in neuromuscular diseases

High Spatial Resolution electromyography (HSR-EMG), a new kind of noninvasive surface EMG based on a spatial filtering technique, was evaluated with respect to the diagnosis of neuromuscular diseases. HSR-EMG measurements were recorded from 61 healthy subjects and 72 patients with different neuromuscular diseases and analyzed quantitatively. The results indicate that a few parameters such as muscular conduction velocity, dwell time over root mean square, autocorrelation function, and chi-value are sufficient to recognize and classify specific signal alterations due to neuromuscular disorders. A diagnostic evaluation procedure calculating automatically the most probable diagnosis from the parameter results could assign the correct diagnosis to about 81% of the investigated patients and healthy subjects. Myopathic disorders were recognized with a sensitivity of 85% (specificity: 97%), neuropathic disorders with a sensitivity of 68% (specificity: 98%). We conclude that HSR-EMG shows a diagnostic validity similar to that described in literature for needle EMG. Moreover, the noninvasive technique provides the advantage of a simple and painless application. © 1997 John Wiley & Sons, Inc. Muscle Nerve 20: 1360–1370, 1997     

Evaluation of persons with suspected lumbosacral and cervical radiculopathy: Electrodiagnostic assessment and implications for treatment and outcomes (Part I)

Persons with back, neck, and limb symptoms constitute a major referral population to specialists in electrodiagnostic (EDX) medicine. The evaluation of these patients involves consideration of both the common and less common disorders. The EDX examination with needle electromyography (EMG) is the most important means of testing for radiculopathy. This test has modest sensitivity but high specificity and well complements imaging of the spine. Needle EMG in combination with nerve conduction testing is valuable in excluding entrapment neuropathies and polyneuropathy―conditions that frequently mimic radicular symptoms. In this first of a two-part review, the optimal EDX evaluation of persons with suspected radiculopathy is presented. In part two, the implications of EDX findings for diagnosis and clinical management of persons with radiculopathy are reviewed.     

Predictive values of motor unit potential analysis in limb muscles

ObjectiveIn interpretation of diagnostic findings the probability that an abnormal test accurately indicates pathology (i.e., the positive predictive value), and a normal test accurately excludes pathology (i.e., the negative predictive value) is the most important. For motor unit potential (MUP) analysis no such data has been published; hence this was the aim of this study.MethodsIn 31 patients with facioscapulohumeral muscular dystrophy (FSHD) and 34 controls the biceps brachii and vastus lateralis muscles were examined by concentric needle electromyography (EMG), using template operated MUP analysis. These results were compared to non-parametric reference data obtained in another group of 34 (biceps brachii) and 46 (vastus lateralis) control subjects.ResultsFor the biceps brachii muscles sensitivity was 59%, specificity 91%, the positive predictive value 85%, and negative predictive value 72% with at least two criteria (mean values or outliers for MUP thickness, amplitude and duration) below the reference intervals. In addition, all subjects with three abnormal EMG criteria were FSHD patients, and 90% of subjects with normal EMG were controls.ConclusionsTemplate operated MUP analysis demonstrated reasonable predictive value for diagnosis and exclusion of myopathy.SignificanceQuantitative MUP analysis seems to be useful for the preliminary diagnosis of FSHD in patients with appropriate clinical picture.     

A positive compression ultrasonography of the lower limb veins is highly predictive of pulmonary embolism on computed tomography in suspected patients

The presence of a clot-- even asymptomatic-- in the proximal lower limb veins of a patient with clinically suspected pulmonary embolism (PE) provides evidence for venous thromboembolism and indicates anticoagulant therapy in such patients. We aimed at assessing the diagnostic performance of compression ultrasonography as compared to multi-slice computed tomography (MSCT) for the diagnosis of PE. We analyzed data from a large outcome management study that included consecutive outpatients referred to the emergency ward with clinically suspected PE. All high clinical probability patients, and all non-high clinical probability patients with a positive D-dimer test underwent both MSCT and CUS. Of the 756 included patients, 232 had PE ruled out on the basis of a negative D-dimer test, and 524 patients underwent both MSCT and CUS. PE was found in 187 out of the 511 patients with a conclusive MSCT. The sensitivity of CUS for the presence of PE on MSCT was 39% (95% confidence interval: 32 to 46%), and its specificity was 99% (95% CI:97 to 100%). Positive and negative likelihood ratios were 42.2 (95% CI: 13.5 to 131.9) and 0.6 (95% CI: 0.5 to 0.7), respectively. We conclude from that large study of unselected patients that CUS has high specificity but low sensitivity, for the diagnosis of PE at MSCT in suspected patients. It allows ruling in the diagnosis of PE without further invasive and/or expensive testing in suspected patients.     

Rapid diagnosis of tuberculous meningitis by polymerase chain reaction assay of cerebrospinal fluid

A polymerase chain reaction (PCR) method for the rapid diagnosis of tuberculous meningitis (TBM) was used to study prospectively 47 cerebrospinal fluid (CSF) samples from 45 patients. Twenty CSF samples were from patients with clinically suspected TBM and another 27 samples came from patients without clinically suspected TBM. Mycobacterial DNA was detected in 15 CSF samples (14 from patients with clinically suspected TBM and 1 from a patient not suspected of having TBM). Of the PCR-positive samples, 4 were also positive for mycobacterial culture. However, 32 PCR-negative samples were all culture-negative. All samples were negative for the acid-fast bacillus by direct smear. The single PCR-positive patient in the clinically unsuspected TBM group was initially diagnosed as suffering from aseptic meningitis on the basis of his clinical features. The mycobacterial culture of his CSF specimen was also positive and a revised diagnosis of an aseptic type of TBM was made. The estimations of specificity and sensitivity in this study were 100% and 70% respectively. The results showed that using a PCR to detect mycobacterial DNA in CSF for the early diagnosis of TBM is not only a rapid but also an accurate method.     

The diagnostic accuracy of magnetic resonance imaging and cerebrospinal fluid cytology in leptomeningeal metastasis

Diagnostic decision making in the case of patients suspected of having leptomeningeal metastasis (LM) can be very difficult. The results of cerebrospinal fluid (CSF) cytology can be repeatedly negative, and the predictive value of gadolinium-enhanced magnetic resonance imaging (MRI) is not well known. We report the results of CSF cytology and Gd MRI in 61 patients with known cancer, suspected of having LM. We combined our data with those from a similar study and calculated the sensitivity and specificity of CSF and Gd MRI, in the absence of a “gold standard diagnosis.” CSF cytology was positive for LM in 35 patients and MRI in 38. With CSF cytology sensitivity 75% and specificity 100%, with Gd MRI sensitivity was 76% but specificity only 77%. We conclude that Gd MRI provides strong support in the diagnosis of LM in patients with cancer who have negative results on CSF cytology. Received: 6 July 1998 Received in revised form: 15 January 1999 Accepted: 3 March 1999     

A rapid and quantitative D-Dimer assay in whole blood and plasma on the point-of-care PATHFAST analyzer

The objective of this study was to evaluate the accuracy indices of the new rapid and quantitative PATHFAST D-Dimer assay in patients with clinically suspected deep-vein thrombosis (DVT). Eighty two consecutive patients (34% DVT, 66% non-DVT) with suspected DVT of a lower limb were tested with the D-Dimer assay with a PATHFAST analyzer. The diagnostic value of the PATHFAST D-Dimer assay (which is based on the principle of a chemiluminescent enzyme immunoassay) for DVT was evaluated with pre-test clinical probability, compression ultrasonography (CUS). Furthermore, each patient underwent contrast venography and computed tomography, if necessary. The sensitivity and specificity of the D-Dimer assay using 0.570 mug/mL FEU as a clinical cut-off value was found to be 100% and 63.2%, respectively, for the diagnosis of DVT, with a positive predictive value (PPV) and negative predictive value (NPV) of 66.7% and 100%, respectively. The correlation between the results of PATHFAST D-Dimer and VIDAS D-Dimer was acceptable (y=1.134x+0.003, r=0.902). The test reproducibility was good (CV%: from 4.0% to 5.0% for plasma and from 7.1% to 7.5% for whole blood) and the total imprecision was very good (CV%: 3.6-5.7%). Whole blood as well as plasma can be used as samples in this assay (y=1.013x-0.010, r=0.971 for heparinized specimens; y=1.068x+0.003, r=0.989 for citrated specimens). Because of its high sensitivity and NPV PATHFAST D-Dimer assay can be useful for the rapid rule out of DVT in patients admitted with suspected thrombosis.     

Results of a new rapid d-dimer assay (cardiac d-dimer) in the diagnosis of deep vein thrombosis.

The objective was to evaluate the accuracy of a new full blood rapid D-dimer assay in the diagnosis of suspected deep vein thrombosis (DVT). In 100 consecutive patients with suspected DVT, clinical probability was staged according to a pretest score proposed by Wells. For the determination of plasma D-dimer, heparin and citrate blood samples were drawn, and Cardiac D-dimer, STA-LIA, and Tina-quant tests were performed. Final diagnosis was confirmed either by duplex sonography or ascending venography. DVT was diagnosed in 37%, thrombophlebitis in 10%, and no venous thromboembolism was diagnosed in 52%. In 2% pulmonary embolism was detected and one patient was dismissed before final diagnosis. Cardiac D-dimer assay from citrate tubes showed a sensitivity of 88.6%, a specificity of 54%, a positive predictive value of 57.4%, and a negative predictive value of 87.1%. Nearly identical results were observed with heparin tubes. Corresponding results were 88.6%, 48%, 52.5%, and 85.7% for STA-LIA and 88.6%, 46%, 53.4%, and 85.2% for Tina-quant, respectively. In conclusion, we can say that Cardiac D-dimer is a rapid, whole blood assay with a great potential for clinical use. It can help in diagnosing DVT from citrate as well as heparin tubes with comparable sensitivity, specificity, positive and negative predictive values as STA-LIA and Tina-quant tests.     

An analysis of the sensitivity and specificity of MHC-I and MHC-II immunohistochemical staining in muscle biopsies for the diagnosis of inflammatory myopathies

Although there have been several previous reports of immunohistochemical staining for MHC antigens in muscle biopsies, there appears to be a lack of consensus about its routine use in the diagnostic evaluation of biopsies from patients with suspected inflammatory myopathy. Positive MHC-I staining is nonspecific but is widely used as a marker for inflammatory myopathy, whilst the role of MHC-II staining is not clearly defined. We investigated the sensitivity and specificity of MHC-I and MHC-II immunostaining for the diagnosis of inflammatory myopathy in a large group of biopsies from a single reference laboratory. Positive staining for MHC-I was found to have a high sensitivity in biopsies from patients with inflammatory myopathy but a very low specificity, as it was also common in other non-inflammatory myopathies and neurogenic disorders. On the other hand, MHC-II positivity had a much higher specificity in all major subgroups of inflammatory myopathy, especially inclusion body myositis. The findings indicate that the combination of MHC-I and MHC-II staining results in a higher degree of specificity for the diagnosis of inflammatory myopathy and that in biopsies with inflammation, positive MHC-II staining strongly supports the diagnosis of an immune-mediated myopathy. We recommend that immunohistochemical staining for both MHC-I and MHC-II should be included routinely in the diagnostic evaluation of muscle biopsies from patients with suspected inflammatory myopathy. However, as the sensitivity and interpretation of MHC staining may depend on the technique used, further studies are needed to compare procedures in different centres and develop standardised protocols.     

CT muscle imaging and the clinical assessment of neuromuscular disease

Twenty patients with neurogenic disorders, polymyositis, or muscular dystrophies were assessed clinically and by CT imaging of limb, limb girdle, and trunk muscles, using a standard protocol. On each side of these patients 26 movements were graded by the MRC scale, and 20 muscles were assessed by CT imaging. The clinical and CT findings could be compared, in a blind evaluation, in 10 muscles on each side. A quantitative assessment of the CT muscle images were also made. The CT images showed striking abnormalities, even in many muscles of normal strength by clinical testing. Asymmetrical involvement of muscles was found in all the disorders studied, even when not suspected on clinical examination. Muscles in patients with muscular dystrophy were more abnormal than those in patients with neurogenic disorders. In polymyositis the attenuation values were intermediate to the other two groups. A “washed-out” appearance with very low attenuation values was very suggestive of muscular dystrophy. Involvement of paraspinal and rectus abdominis muscles was uncommon in neurogenic disorders. The gracilis muscle was relatively resistant to degeneration. CT imaging can enhance the clinical assessment of patients with neuromuscular disease, often revealing unexpected abnormalities. © 1995 John Wiley & Sons, Inc.     

Testing the validity of a set of diagnostic criteria for sensory neuronopathies: a francophone collaborative study

There are no validated criteria for the diagnosis of sensory neuronopathy (SNN) yet. In a preliminary monocenter study a set of criteria relying on clinical and electrophysiological data showed good sensitivity and specificity for a diagnosis of probable SNN. The aim of this study was to test these criteria on a French multicenter study. 210 patients with sensory neuropathies from 15 francophone reference centers for neuromuscular diseases were included in the study with an expert diagnosis of non-SNN, SNN or suspected SNN according to the investigations performed in these centers. Diagnosis was obtained independently from the set of criteria to be tested. The expert diagnosis was taken as the reference against which the proposed SNN criteria were tested. The set relied on clinical and electrophysiological data easily obtainable with routine investigations. 9/61 (16.4 %) of non-SNN patients, 23/36 (63.9 %) of suspected SNN, and 102/113 (90.3 %) of SNN patients according to the expert diagnosis were classified as SNN by the criteria. The SNN criteria tested against the expert diagnosis in the SNN and non-SNN groups had 90.3 % (102/113) sensitivity, 85.2 % (52/61) specificity, 91.9 % (102/111) positive predictive value, and 82.5 % (52/63) negative predictive value. Discordance between the expert diagnosis and the SNN criteria occurred in 20 cases. After analysis of these cases, 11 could be reallocated to a correct diagnosis in accordance with the SNN criteria. The proposed criteria may be useful for the diagnosis of probable SNN in patients with sensory neuropathy. They can be reached with simple clinical and paraclinical investigations.     

Diagnostic value of the D-dimer test in deep vein thrombosis: improved results by a new assay method and by using discriminate levels

Previous studies have suggested that D-dimer testing reliably selects patients for whom duplex sonography should be performed for diagnosis of deep vein thrombosis (DVT). However, the interassay correlation is poor. Therefore, we tested four D-dimer methods for their ability to rule out DVT, including the Miniquant test, a new D-dimer assay method. Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were calculated vs. duplex sonography. Twenty-nine of 108 (27%) patients with suspected DVT were diagnosed as having DVT by sonography. The Vidas enzyme-linked immunoabsorbent assay (ELISA) test, the Miniquant turbidimetric test and the latex agglutination test for D-dimer all provided discriminate values for achieving 100% sensitivity and 100% NPV. D-dimer results demonstrated higher specificity and PPV in the outpatient vs. the inpatient group. This probably reflects the higher proportion of inpatients with comorbid conditions, such as malignancy and postsurgery status, in whom D-dimer results show very poor specificity and PPV. The new Miniquant turbidimetric assay performed as well as the more established ELISA method. We conclude that the D-dimer tests were shown to possess the necessary sensitivity and NPV to be useful in screening patients with suspected DVT. A negative D-dimer test in selected patients could be helpful in reducing the number of sonograms performed for diagnosis of DVT.     

Myopathology in times of modern imaging

Over the last two decades, muscle (magnetic resonance) imaging has become an important complementary tool in the diagnosis and differential diagnosis of inherited neuromuscular disorders, particularly in conditions where the pattern of selective muscle involvement is often more predictive of the underlying genetic background than associated clinical and histopathological features. Following an overview of different imaging modalities, the present review will give a concise introduction to systematic image analysis and interpretation in genetic neuromuscular disorders. The pattern of selective muscle involvement will be presented in detail in conditions such as the congenital or myofibrillar myopathies where muscle imaging is particularly useful to inform the (differential) diagnosis, and in disorders such as Duchenne or fascioscapulohumeral muscular dystrophy where the diagnosis is usually made on clinical grounds but where detailed knowledge of disease progression on the muscle imaging level may inform better understanding of the natural history. Utilizing the group of the congenital myopathies as an example, selected case studies will illustrate how muscle MRI can be used to inform the diagnostic process in the clinico‐pathological context. Future developments, in particular, concerning the increasing use of whole‐body MRI protocols and novel quantitative fat assessments techniques potentially relevant as an outcome measure, will be briefly outlined.     

Utility of trapezius EMG for diagnosis of amyotrophic lateral sclerosis

Needle electromyography (EMG) of the tongue is traditionally used as a key to the diagnosis of amyotrophic lateral sclerosis (ALS), although relaxation of the tongue is often difficult to achieve. Recently, frequent abnormalities in the EMGs of the sternocleidomastoid (SCM) and upper trapezius muscles in ALS have been reported. To elucidate the diagnostic utility of these muscles we performed a multicenter prospective study to examine EMGs of the tongue (genioglossus), SCM, and trapezius in 104 ALS or suspected ALS patients. We also examined EMGs of the SCM and trapezius in 32 cervical spondylosis (CS) patients. We mainly evaluated fibrillation potentials/positive sharp waves (Fib/PSWs) and fasciculation potentials. Complete relaxation was achieved in 85% of ALS patients in the trapezius, but in only 6% of patients in the tongue. Fib/PSWs were observed in 8%, 13%, and 45% of ALS patients in the tongue, SCM, and trapezius, respectively, whereas fasciculation potentials were observed in 1%, 7%, and 39%, respectively. Abnormal spontaneous activity of any type was found in 9%, 17%, and 63% of patients, respectively. The high frequency of abnormal spontaneous activity in the trapezius was similar among the different diagnostic categories, and even 72% of clinically suspected ALS (progressive muscular atrophy) patients showed them in their trapezius. We did not observe Fib/PSWs or fasciculation potentials in any of our CS patients, thus these findings have excellent specificity. Tongue EMG added little utility over the clinical sign of tongue atrophy. Abnormal spontaneous activity in the trapezius would be more useful for the early diagnosis of ALS. Muscle Nerve 39: 63–70, 2009     

Clinical usefulness of D-dimer testing in cancer patients with suspected pulmonary embolism

Limited data are available about the diagnostic value of D-dimer testing in cancer patients with clinically suspected pulmonary embolism (PE). Therefore, we evaluated i) the safety and clinical usefulness of an ELISA D-dimer test to rule out PE in cancer patients compared with non-cancer patients and ii) whether adopting a higher D-dimer cut-off value might increase the usefulness of D-dimer in cancer patients. We analysed data from two outcome studies which enrolled 1,721 consecutive patients presenting in the emergency department with clinically suspected PE. Presence of an active malignancy was abstracted from the database. All patients underwent a sequential diagnostic work-up including an ELISA D-dimer test and a 3-month followup. Sensitivity and predictive value (NPV) were 100% in both cancer and non-cancer patients. PE was ruled out by a negative D-dimer test in 494/1,554 (32%) patients without cancer, and in 18/164 (11%) patients with a malignancy. At cut-off values varying from 500 to 900 microg/l, the sensitivity was unchanged (100%, 95% CI: 93% to 100%) and the specificity increased from 16% (95% CI: 11% to 24%) to 30% (95% CI: 22% to 39%). The 3-month thromboembolic risk was 0% (95% CI: 0% to 18%) in cancer patients with a negative D-dimer test. ELISA D-dimer appears safe to rule out pulmonary embolism in cancer patients but it is negative in only one of ten patients at the usual cut-off value. Increasing the cut-off value of D-dimer in cancer patients might increase the test's clinical usefulness.     

Clinical evaluation of a monoclonal antibody-based enzyme immunoassay for fibrin degradation products in patients with clinically suspected pulmonary embolism. ANTELOPE-Study Group

We prospectively evaluated the diagnostic accuracy of the Fibrinostika FbDP assay in 304 consecutive patients with suspected pulmonary embolism and examined potentially useful cut-off points at which the disease can be excluded. The prevalence of pulmonary embolism was 31%. The assay generated an area under the Receiver Operating Characteristic curve of 0.79 (95% CI 0.73-0.84). A cut-off point of 0.05 microg/ml yielded a sensitivity, specificity, negative predictive value and an exclusion efficiency of 100% (95% CI 96-100), 5% (95% CI 2-9), 100% (95% CI 69-100) and 3% (95% CI 2-6), respectively. A clinically useful cut-off point seems to be 0.11 microg/ml which corresponded with a sensitivity, specificity, negative predictive value and an exclusion efficiency of 96% (95% CI 90-99), 27% (95% CI 24-28), 93% (95% CI 84-98) and 20% (95% CI 16-25), respectively. We conclude that the assay has potential clinical utility for the exclusion of pulmonary embolism, but it cannot be used as a sole test.     

Hoover's sign for the diagnosis of functional weakness: A prospective unblinded cohort study in patients with suspected stroke

ObjectiveHoover's sign – weakness of voluntary hip extension with normal involuntary hip extension during contralateral hip flexion against resistance – is a commonly used sign in the diagnosis of functional weakness of the lower limb. However, little is known about the performance of this sign in clinical practice.MethodsHoover's sign was tested as part of the diagnostic work-up of 337 patients presenting to hospital with suspected stroke. We made a gold-standard diagnosis of stroke, functional disorder, or other diagnosis based on clinical history and examination, imaging and clinical follow-up. We calculated the sensitivity, specificity, positive and negative predictive values of Hoover's sign for a diagnosis of functional weakness in patients who presented with leg weakness.ResultsWe consecutively recruited 337 consecutive patients with suspected stroke, 124 of whom presented with leg weakness. 8 of these patients had a diagnosis of functional disorder. The sensitivity of Hoover's sign for a diagnosis of functional weakness in those who presented with leg weakness was 63% (95% CI: 24 to 91), and the specificity was 100% (95% CI: 97 to 100).ConclusionsIn this cohort, Hoover's sign was moderately sensitive and very specific for a diagnosis of functional weakness. Further studies are required to assess inter-observer variability and performance of the test in larger numbers of patients with functional weakness.     

Application of the new McDonald criteria to patients with clinically isolated syndromes suggestive of multiple sclerosis

Traditionally, multiple sclerosis (MS) has been diagnosed on the basis of clinical evidence of dissemination in time and space. Previously, it could not be diagnosed in patients with single clinical episodes of demyelination known as clinically isolated syndromes. New diagnostic criteria from the International Panel of McDonald and colleagues incorporate MRI evidence of dissemination in time and space to allow a diagnosis of MS in patients with clinically isolated syndromes. From clinical and MRI examinations performed prospectively at baseline, 3 months, 1 year, and 3 years of follow-up, the frequency of developing MS was ascertained by the application of both the new McDonald criteria and the Poser criteria for clinically definite MS. The specificity, sensitivity, positive and negative predictive value, and accuracy of the new criteria for the development of clinically definite MS were assessed. At 3 months, 20 of 95 (21%) patients had MS with the McDonald criteria, whereas only 7 of 95 (7%) had developed clinically definite MS. After 1 year, the corresponding figures were 38 of 79 (48%) and 16 of 79 (20%), and after 3 years, they were 29 of 50 (58%) and 19 of 50 (38%). The development of MS with the new MRI criteria after 1 year had a high sensitivity (83%), specificity (83%), positive predicative value (75%), negative predictive value (89%), and accuracy (83%) for clinically definite MS at 3 years. Use of the new McDonald criteria more than doubled the rate of diagnosis of MS within a year of presentation with a clinically isolated syndrome. The high specificity, positive predictive value, and accuracy of the new criteria for clinically definite MS support their clinical relevance.     

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.