D-dimer Assay In Patients Research Articles

PB1013 Evaluation of the Diagnostic Performance of Three D-Dimer Assays in Patients with Suspected Deep Vein Thrombosis

PB1013 Evaluation of the Diagnostic Performance of Three D-Dimer Assays in Patients with Suspected Deep Vein Thrombosis

Evaluation of the diagnostic performance of three D-dimer assays in patients with suspected deep vein thrombosis: STA-Liatest D-Di plus, Tina-quant D-dimer Gen. 2, and INNOVANCE D-dimer

IntroductionD-dimer is a crucial test to exclude deep vein thrombosis (DVT). We aimed to evaluate the performance of three D-dimer assays: STA-Liatest D-Di Plus (Diagnostica Stago), Tina-quant D-Dimer Gen. 2 (Roche Diagnostics), and INNOVANCE D-Dimer (Siemens Healthineers Diagnostics) in the exclusion of DVT. MethodsSamples (n = 1032) and clinical data were acquired from a prospective outcome study (Rivaroxaban for Scheduled Work-up of Deep Vein Thrombosis – the Ri-Schedule study), which included patients referred to the emergency department with suspected lower-limb DVT. D-dimer was determined with STA-Liatest, and only patients with positive D-dimer values (≥0.5 μg/mL) as stand-alone, were referred for compression ultrasonography to confirm or exclude DVT. Patients were followed up 90 days after inclusion. Samples were also analyzed with Tina-quant Gen. 2, and INNOVANCE assays. The diagnostic performances of the three assays were investigated. ResultsPositive D-dimer (≥0.5 μg/mL) was found in 733 patients (71%) with STA-Liatest, 691 patients (67%) with Tina-quant Gen. 2, and 766 (74%) with INNOVANCE. DVT was confirmed by compression ultrasonography in 196 patients (27%) with positive D-dimer with STA-Liatest. Of those, six (3%) had negative D-dimer (<0.5 μg/mL) with at least one of the three assays yielding a failure rate of 0.7% with STA-Liatest, 2% with Tina-quant Gen. 2, and 2% with INNOVANCE. The sensitivity and negative predictive value (NPV) for STA-Liatest were 99.0% (95% CI 96.4–99.9) and 99.3% (95% CI 97.4–99.8), for Tina-quant Gen. 2 97.5% (95% CI 94.1–99.2) and 98.5% (95% CI 96.6–99.4), and for INNOVANCE 98.0% (95% CI 94.9–99.0) and 98.5% (95% CI 96.1–99.4) respectively. The efficiency to exclude DVT based on D-dimer as a stand-alone test was 29% (95% CI 26–33) for STA-Liatest, 33% (95% CI 30–37) for Tina-quant Gen. 2, and 26% (95% CI 23–29) for INNOVANCE. ConclusionSTA-Liatest, Tina-quant Gen. 2, and INNOVANCE showed good performances with sensitivity ≥97% and NPV ≥98%. The efficiency to exclude DVT varied and was highest for Tina-quant Gen. 2, whereas the failure rate was lowest for STA-Liatest.

Diagnostic approach and use of CTPA in patients with suspected pulmonary embolism in an emergency department in Saudi Arabia.

In patients with suspected pulmonary embolism (PE), the literature suggests the overuse of computerized tomography pulmonary angiography (CTPA) and underuse of clinical decision rules before imaging request. This study determined the potential for avoidable CTPA using the modified Wells score (mWS) and D-dimer assay in patients with suspected PE. This hospital-based retrospective study analyzed the clinical data of 661 consecutive patients with suspected PE who underwent CTPA in the emergency department of a tertiary hospital for the use of a clinical prediction rule (mWS) and D-dimer assay. The score was calculated retrospectively from the available data in the files of patients who did not have a documented clinical prediction rule. Overuse (avoidable) CTPA was defined as D-dimer negativity and PE unlikely for this study. Of 661 patients' data examined, clinical prediction rules were documented in 15 (2.3%). In total, 422 patients (63.8%) had required information on modified Wells criteria and D-dimer assays and were included for further analysis. PE on CTPA was present in 22 (5.21%) of PE unlikely (mWS ≤4) and 1 (0.24%) of D-dimer negative patients. Thirty patients (7.11%) met the avoidable CTPA (DD negative+PE unlikely) criteria, and it was significantly associated with dyspnea. The value of sensitivity of avoidable CTPA was 100%, whereas the positive predictive value was 90.3%. Underutilization of clinical prediction rules before prescribing CTPA is common in emergency departments. Therefore, a mandatory policy should be implemented regarding the evaluation of avoidable CTPA imaging to reduce CTPA overuse.

Underuse of risk assessment and overuse of computed tomography pulmonary angiography in patients with suspected pulmonary thromboembolism.

Evidence suggests the potential overuse of computed tomography pulmonary angiography (CTPA) in patients with suspected pulmonary thromboembolism (PTE) in the absence of consistent use of pre-test clinical prediction rules and D-dimer assays. To evaluate use and diagnostic utility of clinical prediction rules and D-dimer assay in patients with suspected PTE and quantify potentially avoidable overuse of CTPA in low risk patients. A total of 344 consecutive patients undergoing CTPA at a tertiary hospital was studied with regards to the use of D-dimer assays and clinical prediction rules for PTE. For each patient, a modified Wells score (mWS), revised Geneva score and PISA model were calculated retrospectively; performance characteristics for each rule for PTE were determined with reference to results of CTPA. Results for the mWS and D-dimer assays (when performed) were used to estimate the overuse of CTPA according to risk category. Use of a clinical prediction rule was documented in only 5.0% of cases. Of 269 low-risk patients who had a calculated mWS ≤4, only 64 (23.8%) had a D-dimer assay performed, with 30 (11.1%) having a PTE on CTPA. Among 75 patients with an mWS >4, 23 (30.7%) had a PTE on CTPA (P < 0.001). Compared to other prediction rules, an mWS>4 had the highest positive predictive value (31.0%) for PTE; all rules demonstrated similar negative predictive values for low-risk scores (87-89%). After adjusting for an 11% false negative rate for PTE in patients with low-risk mWS, overuse of CTPA was reported in up to 190 (55.2%) patients. More than 50% of patients with suspected PTE may be subject to unwarranted use of CTPA in the absence of pre-test clinical prediction rules coupled with D-dimer assays.

Application of a decision rule and a D-dimer assay in the diagnosis of pulmonary embolism

Current strategies for diagnosing pulmonary embolism (PE) include a clinical decision rule (CDR), followed by a D-dimer assay in patients with an unlikely clinical probability. We assessed the implementation of the current guidelines for the diagnosis of PE. A first questionnaire was sent to internists and pulmonologists to assess the proportion of physicians that adequately applied the guidelines. Two versions of a second questionnaire were sent presenting five hypothetical cases of which in two cases with an intermediate clinical probability an abnormal D-dimer test result was added to one version. We assessed the variation of the CDR and compared the proportions of a likely clinical probability between the two versions. A total of 65 physicians responded to the first questionnaire (response rate 75%). Half of the physicians (N=29; 46%) indicated that they use a CDR in all patients and 22 physicians (45%) indicated that they review the D-dimer result after they examined patients. Sixty-two physicians responded on the second questionnaire (response rate 36%). A shift was observed from an unlikely to a likely probability when an abnormal D-dimer test result was added to the clinical information (22% to 41%; p=0.22 and 26% to 50%; p<0.05). Our findings indicate that physicians do not use the guidelines for diagnosis of PE consistently. Furthermore, the knowledge of an abnormal D-dimer test result before seeing the patient leads to a higher CDR score. Physicians should therefore first examine patients before taking note of the D-dimer test result.

An age‐adapted approach for the use of D‐dimers in the exclusion of deep venous thrombosis

A normal D-dimer (DD) concentration for the exclusion of deep venous thrombosis (DVT) has a low specificity in older patients and compression ultrasonography is often required. Three D-dimer assays, STA Liatest, Tina-quant, and Innovance, are evaluated in symptomatic outpatients suspected for DVT with emphasis on its performance in older patients by using different cut-off levels. This study includes 466 outpatients suspected for having DVT. The diagnostic accuracy, measured as sensitivity and area under the curve of the receiver operation characteristic curve is good for all DD assays. The specificity of the DD assays combined with a low pretest probability varies from 42.6 to 51.5%. The specificity of the three DD assays in patients > or = 60 years varies, however, between 24.6 and 40.9%. Several cut-off values in different age-subgroups are studied. For patients < 60 years, the most accurate cut-off value is 500 microg/L for all DD assays. For patients > or = 60 years, a threshold of 750 microg/L has the best results with NPV of 100% for all assays and specificity of 48.5% (STA Liatest), 60.6% (Tina-quant), and 49.2% (Innovance), respectively. For the three assays, the number needed to test (NNT) decreases in both subgroups of patients compared to the standard algorithm. A cut-off level of 750 microg/L for patients > or = 60 years improves the clinical performance of DD assays in combination with the PTP score without the loss of NPV. The NNT improves substantially with an age-adapted algorithm.

Late-onset rhabdomyolysis in pneumococcal meningitis: a case report

idation of Wells criteria in the evaluation of patients with suspected pulmonary embolism. Ann Emerg Med 44:503–510 14. Le Gal G, Righini M, Roy PM et al (2006) Prediction of pulmonary embolism in the emergency department: the revised Geneva score. Ann Intern Med 144:165–171 15. Swensen S, Sheedy P, Ryu J et al (2002) Outcomes after withholding anticoagulation from patients with suspected acute pulmonary embolism and negative computed tomographic findings: a cohort study. Mayo Clin Proc 77:130–138 16. Perrier A, Roy P, Sanchez O et al (2005) Multidetector-row computed tomography in suspected pulmonary embolism. N Engl J Med 352:1760–1768 17. van Belle A, Buller H, Huisman M et al (2006) Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography. JAMA 295:172–179 18. Stein P, Fowler S, Goodman L et al (2006) Multidetector computed tomography for acute pulmonary embolism. N Engl J Med 354:2317–2327 19. Righini M, Aujesky D, Roy P et al (2004) Clinical usefulness of D-dimer depending on clinical probability and cutoff value in outpatients with suspected pulmonary embolism. Arch Int Med 164:2483–2487 20. Burkill G, Bell J, Chinn R et al (2002) The use of a D-dimer assay in patients undergoing CT pulmonary angiography for suspected pulmonary embolus. Clin Radiol 57:41–46

Valeur des D-dimères lors des thromboses veineuses superficielles des membres inférieurs

ObjectiveThe negative predictive value of D-dimer (DD) assay in patients with venous thromboembolic disease is well established for deep vein thrombosis and pulmonary embolism. Little is known about the value of DD assay in patients with superficial thrombophlebitis (ST). The purpose of this study was to assess the value of DD assay in patients with ST of the lower limb. MethodThe study group was composed of 100 consecutive patients, irrespective of age. Patients with clinical manifestations suggestive of ST of the lower limbs with positive duplex color Doppler evidence confirming the diagnosis and DD assay results (Vidas D-Dimer Exclusion) within 24 hours were included in the study. Patients with thrombosis in another site in addition to the superficial vein of the lower limb, those taking anticoagulants for more than 48 hours, and those with a condition known to potentially elevate DD levels were excluded. The volume of the thrombus was determined echographically and reported as mean diameter and length. ResultsSixty-two women and 38 men were included. Mean age (± 5) was 58 years ± 13.48 (range 18–90; median: 57). The ST involved the Great saphenous (n=74), the small saphenous (n=11) or another vein (n=15). Mean thrombus volume was 4453 mm3 ± 7101 (range 94–38484; median: 1751). Mean DD level was 829 ng/ml ± 516.72 (range 100–2567; median: 715.5). DD assay was negative (<500 ng/ml) in 32 patients (32%) and positive in 68 (68%). For these three items, there was no significant difference between ST with and without varicose veins. DD assay was always positive (≥500 ng/ml) in all patients aged over 70 years (n=22). In patients aged less than 70 years (n=78), DD assay was positive in 46 (59%) and negative in 32 (41%). DD level was positively correlated with thrombus volume in patients aged less than 70 years (P<0.0001). ROC analysis, sensitivity as a function of specificity by thrombus volume for the entire population, determined the usefulness of a negative DD assay. Considering the critical threshold at 5914 mm3, sensitivity was 1.0 (95CI 0.89–1.0), with 0.29 specificity (95CI 0.19–0.42), 1.00 negative predictive value and 0.75 positive predictive value. However, the thrombus volume was less than this threshold value in three of the nine cases of ST with extension to the terminal portion of the saphenous. ConclusionA positive DD assay was observed in 68% of patients with ST, with no significant difference with or without varicose veins. The test was positive in all patients aged over 70 years and in 59% of those aged under 70 years. There was a correlation between DD level and thrombus volume, yielding a threshold volume (5914 m3) above which all DD tests were positive. Nevertheless, this threshold volume was too great to include all ST extending to the terminal portion of the saphenous. Measurement of DD level is thus not contributive to the diagnosis of ST.

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.

D-dimer is not useful for the diagnosis of isolated superficial venous thrombosis

D-dimer is not useful for the diagnosis of isolated superficial venous thrombosis

A Comparison of Spiral Computed Tomography and Latex Agglutination D-dimer Assay in Acute Pulmonary Embolism using Pulmonary Arteriography as Gold Standard

Objective : To compare the diagnostic accuracy of contrast medium enhanced spiral computed tomography of the pulmonary arteries (s-CTPA) and a latex agglutination D-dimer assay in patients with suspected acute pulmonary embolism (PE) by using pulmonary arteriography (PA) and clinical follow-up as reference method. Design : Ninety hemodynamically stable patients with symptoms of acute pulmonary embolism were prospectively evaluated with s-CTPA and pulmonary arteriography (PA) within 24 h from admission. Plasma D-dimer levels on admittance were analyzed using a rapid latex agglutination D-dimer assay. The outcome of D-dimer concentrations in plasma below 0.25 and 0.5 mg/l was studied. Results : All PA and s-CTPA investigations were regarded as of acceptable diagnostic quality in a consensus reading. Thirty-three patients had a positive PA (37%). Three patients had false negative and two patients had false positive s-CTPA findings. s-CTPA had 91% sensitivity, 96% specificity, 94% positive predictive value (PPV) and 95% negative predictive value (NPV). The sensitivity and specificity for D-dimer below 0.5 mg/l were 79 and 88%, respectively. The PPV and NPV were 81 and 87%. If a cut-off level of 0.25 mg/l was used the corresponding figures were 91, 65, 63 and 92%. Conclusion : s-CTPA has a higher sensitivity and specificity than latex agglutination D-dimer. A cut-off level of 0.25 mg/l can be used as screening method, but s-CTPA must be performed to exclude false positive cases.

Preliminary Evaluation of two New Rapid Immunoturbidimetric D-dimer Assays in Patients with Clinically Suspected Venous Thromboembolism (VTE)

The practical utility and diagnostic accuracy of two new rapid, automated and quantitative immunoturbidimetric D-dimer methods have been evaluated in a population of 123 randomly selected patients with suspected VTE. The STA Liatest D-dimer and MDA D-dimer methods are based on the photo-optical measurement of the rate of agglutination of antibody-coated latex particles. The VIDAS D-dimer automated Elisa was used as the reference method. Diagnosis was confirmed in 51 patients (29 PE, 19 DVT, 3 DVT+PE). The immunoturbidimetric methods compared favorably with the VIDAS Elisa as judged from the correlation coefficients of linear regression lines (r = 0.82, MDA vs VIDAS; r = 0.75, STA vs VIDAS) and areas under the curve of ROC plots (VIDAS 0.83; STA 0.83; MDA 0.81). At a discriminant value of 500 ng/mL, all three D-dimer assays showed high sensitivity (96-98%), high NPV (93-97%) and moderate specificity (39-42%). Reproducibility of results around the cut-off is an important aspect of the diagnostic utility of D-dimer assays. CV's of duplicate determinations in this critical zone showed average values of 5.4% and 17.0% for MDA and STA, respectively. These data demonstrate that such rapid and automated latex-based methods for the quantitative measurement of D-dimer hold promise as reliable and cost-efficient approaches for the exclusion of VTE. Prospective patient management studies will be required to confirm this.

Clinical utility of a rapid whole-blood D-dimer assay in patients with cancer who present with suspected acute deep venous thrombosis.

Although D-dimer assays have high negative predictive values for the diagnosis of deep venous thrombosis, their accuracy in patients with cancer is uncertain. To compare the clinical utility of a whole-blood D-dimer assay for the diagnosis of deep venous thrombosis in patients with and those without cancer. Retrospective analysis of three prospective studies. Two tertiary care hospitals. 1068 consecutive outpatients with suspected deep venous thrombosis. All patients underwent D-dimer testing and assessment with a priori diagnostic strategies that incorporated impedance plethysmography, compression ultrasonography, or contrast venography. Patients in whom deep venous thrombosis was not diagnosed initially were followed for 3 months for the development of thrombosis. Results of D-dimer testing were assessed according to the final diagnosis based on objective testing and clinical follow-up. Cancer status was identified at presentation. The prevalence of deep venous thrombosis was 48.8% in 121 patients with cancer and 14.6% in 947 patients without cancer. Although the sensitivity of the D-dimer assay was similar in patients with and those without cancer (86.4% [95% CI, 75.0% to 94.0%] and 82.6% [CI, 75.2% to 88.5%], respectively), the specificity was significantly lower in patients with cancer (48.4% [CI, 35.5% to 61.4%] and 82.2% [CI, 79.4% to 84.8%]), as was the negative predictive value (78.9% [CI, 62.7% to 90.4%] and 96.5% [CI, 94.9% to 97.8%]). In contrast, the likelihood ratios of a negative test result (0.28 [CI, 0.14 to 0.56] and 0.21 [CI, 0.15 to 0.31]) did not differ significantly. A negative D-dimer test result in patients with cancer does not reliably exclude deep venous thrombosis because the negative predictive value of the test is significantly lower in these patients than in patients without cancer.

Sensitivity and specificity of a rapid whole-blood assay for D-dimer in the diagnosis of pulmonary embolism.

Patients with suspected pulmonary embolism often have nondiagnostic lung scans and may present in circumstances where lung scanning is unavailable. Levels of D-dimer, a fibrin-specific product, are increased in patients with acute thrombosis; this may simplify the diagnosis of pulmonary embolism. To determine the sensitivity and specificity of a whole-blood D-dimer assay in patients with suspected pulmonary embolism and in subgroups of patients with low pretest probability of pulmonary embolism or nondiagnostic lung scans. Prospective cohort. Four tertiary care hospitals. 1177 consecutive patients with suspected pulmonary embolism. All patients underwent an assessment of pretest probability by use of a standardized clinical model, a D-dimer assay, ventilation-perfusion lung scanning, and bilateral compression ultrasonography. Patients in whom pulmonary embolism was not initially diagnosed were followed for 3 months. Accordingly, patients were categorized as positive or negative for pulmonary embolism. Of the 1177 patients, 197 (17%) were classified as positive for pulmonary embolism. Overall, the D-dimer assay showed a sensitivity of 84.8% and a specificity of 68.4%. In 703 patients (3.4%) with a low pretest probability of pulmonary embolism, the likelihood ratio associated with a negative D-dimer test result was 0.27, resulting in a posterior probability of 1.0% (95% CI, 0.3% to 2.2%). In 698 patients with nondiagnostic lung scans (previous probability, 7.4%), the likelihood ratio associated with a negative D-dimer test result was 0.36, resulting in a posterior probability of 2.8% (CI, 1.4% to 4.8%). A normal D-dimer test result is useful in excluding pulmonary embolism in patients with a low pretest probability of pulmonary embolism or a nondiagnostic lung scan.

Evaluation of a new, rapid, and quantitative D-Dimer test in patients with suspected pulmonary embolism.

Previous studies have suggested the utility of D-Dimer ELISA assays in eliminating a diagnosis of pulmonary embolism (PE). Our objectives were to evaluate the performance of a new, rapid, quantitative, and automated Liatest D-Dimer Assay in patients with suspected PE. Three hundred eighty-six consecutive patients referred to our institution between March 1992 and December 1996 for clinically suspected PE, with recent clinical signs not exceeding 1 wk, were included in this study. Diagnosis of PE was based on clinical evaluation, radionuclide lung imaging, lower limb examination, and, when required, pulmonary angiography. D-Dimer performances, for both Liatest D-Dimer and standard D-Dimer ELISA (Asserachrom DDi), assays, were assessed at the end of the study. Among the 386 patients tested, 146 (37.8%) were classified as PE-positive. Liatest D-Dimer assay had a 100% sensitivity (95% confidence interval, 97 to 100%) and a negative predictive value of 100% (95% confidence interval, 94 to 100%). A normal result, below the cutoff of 500 ng/ml, occurred in 83 of the 386 (21%) patients. There was a strong agreement between Liatest D-Dimer and Asserachrom DDi analyses. These findings suggest that this rapid, quantitative, and automated D-Dimer assay provides a useful diagnostic tool for the clinician with regard to exclusion of PE.

Evaluation of a New Rapid Quantitative D-dimer Assay in Patients with Clinically Suspected Deep Vein Thrombosis

The sensitivity and specificity for deep vein thrombosis (DVT) of a new rapid, quantitative and precise (total imprecision < 10%) D-dimer assay suitable for individual measurements (VIDAS D-DIMER, bio-Mérieux, France) were evaluated in a consecutive series of 103 in- and out-patients submitted to serial compression ultrasonography (C-US) for the clinical suspicion of DVT (n = 66) or of DVT recurrence (n = 37) and symptoms lasting from 1 to 15 days. DVT was found in 22 patients at baseline testing and no patient with an initially negative C-US developed vein incompressibility at follow up. The time elapsed from the onset of symptoms was negatively associated with D-dimer levels both in patients with and in those without DVT. In the entire series of patients, the sensitivity of a positive D-dimer test ( > or = 1.0 microgram/ml) for the presence of DVT was 96% (21/22 patients, 95% confidence interval 75-100%) with a specificity of 75% (64-84%), a negative predictive value of 98% (90-100%), a positive predictive value of 51% (35-67%), and an overall accuracy of 80% (70-87%). A normal D-dimer value (0.22 microgram/ml) was observed in one patient with DVT and symptoms lasting from 15 days. The approach of withholding C-US testing in patients with symptoms lasting from less than 11 days and D-dimer levels below the cut-off value was compared to serial C-US testing alone in a cost-effectiveness analysis subdividing the 66 patients with a first episode according to their clinical pretest probability of DVT. Thrombosis was detected in 6.7% of the patients in the low probability group (n = 15), 16.7% of the patients in the moderate probability group (n = 24), 51.9% of the patients in the high probability group (n = 27) and 8.1% of patients with suspected DVT recurrence. Calculated cost-savings for each DVT diagnosed ranged from 5% in the high pretest probability group to 55% in the low pretest probability group and to 77% in patients with suspected DVT recurrence. The safety of avoiding C-US testing in symptomatic patients with a negative D-dimer test should be evaluated in clinical management studies.

A Comparative Analysis of D-Dimer Assays in Patients with Clinically Suspected Pulmonary Embolism

To avoid angiography in patients with clinically suspected pulmonary embolism and non-diagnostic lung scan results, the use of D-dimer has been advocated. We assessed plasma samples of 151 consecutive patients with clinically suspected pulmonary embolism. Lung scan results were: normal (43), high probability (48) and non-diagnostic (60; angiography performed in 43; 12 pulmonary emboli). Reproducibility, cut-off values, specificity, and percentage of patients in whom angiography could be avoided (with sensitivity 100%) were determined for two latex and four ELISA assays. The latex methods (cut-off 500 micrograms/l) agreed with corresponding ELISA tests in 83% (15% normal latex, abnormal ELISA) and 81% (7% normal latex, abnormal ELISA). ELISA methods showed considerable within- (2-17%) and between-assay variation (12-26%). Cut-off values were 25 micrograms/l (Behring), 50 micrograms/l (Agen), 300 micrograms/l (Stago) and 550 micrograms/l (Organon). Specificity was 14-38%; in 4-15% of patients angiography could be avoided. We conclude that latex D-dimer assays appear not useful, whereas ELISA methods may be of limited value in the exclusion of pulmonary embolism.