The use of a D-dimer assay in patients undergoing CT pulmonary angiography for suspected pulmonary embolus

Evaluation of serum endothelial cell specific molecule-1 (endocan) levels as a biomarker in patients with pulmonary thromboembolism

The aim of this study was to investigate the relationship between pulmonary thromboembolism (PTE) and serum endocan levels. The study included 46 patients with a diagnosis of PTE and control group (25 healthy individuals). Serum endocan levels in all participants' blood samples were measured. The average age of the individuals was 61.76 ± 16.39 years. There was a significant difference in the serum endocan levels between the patients and those of the control group [321.93 ng/l (111.35-2511.33) and 192.77 ng/l (118.30-309.02), respectively; P < 0.030]. The serum endocan levels in the submassive [469.41 ng/l (258.13-800.54)] and the massive PTE groups [719.18 ng/l (319.84-2511.33)] were statistically higher than those in the control group [192.77 ng/l (118.30-309.02)] (P < 0.001 and P < 0.001, respectively). In addition, there was a statistically significant difference between the serum endocan levels of the nonmassive PTE group [188.57 ng/l (111.35-685.56)] and the submassive PTE group (P < 0.01). The serum endocan levels correlated with the international normalization ratio (INR), right ventricular dilatation (RVD) and SBP (r = 0.418, P = 0.004; r = 0.659, P < 0.001; r = -0.425, P = 0.003, respectively). In conclusion, serum endocan levels can be considered a practicable biomarker to determine the severity of PTEs and follow-up thrombolytic therapy.

Predicting pulmonary embolus in orthopedic trauma patients using the Wells score

The decision to perform computed tomography pulmonary angiography (CTPA) to rule out pulmonary embolism (PE) in orthopedic trauma patients is challenging. The Wells score is a commonly used clinical probability tool developed to determine the likelihood of PE and assist in determining the need for CTPA examination. This study evaluated the usefulness of the Wells score for predicting PE in patients admitted to the orthopedic trauma service. All patients who were admitted to the orthopedic trauma service at the authors' institution between 2001 and 2011 who underwent CTPA were identified. The Wells score was calculated retrospectively for each patient, and risk categories using the traditional and alternative interpretations of the Wells score were assigned. Pulmonary embolism was diagnosed in 27 (16%) of 169 patients who underwent CTPA. In total, 27 (0.39%) of 6854 patients admitted to the orthopedic trauma service were diagnosed with PE during initial hospitalization. Mean Wells score was 3.31 (95% confidence interval, ±.28) for the entire population, 3.32 for those without PE (95% confidence interval, ±.31), and 3.28 for those with PE (95% confidence interval, ±.72) (P=.91). Average times from admission to CTPA examination for those with and without PE were 6.18 and 5.7 days, respectively (P=.94). No significant correlation existed between the Wells score and CTPA results, indicating that the Wells score is limited in predicting PE risk in orthopedic trauma patients.

D-dimer in the diagnostic workup of suspected pulmonary thrombo-embolism at high altitude

BACKGROUND

Pulmonary thrombo-embolism (PTE) is relatively common in high altitude areas where radiological diagnostic facilities are usually not available. So this study was undertaken to use the results of D-dimer assay to determine the need for imaging studies in patients suspected of having PTE at high altitude.

METHODS

A total of 101 patients at an altitude of > 3,000 m suspected of having PTE were evacuated. D-dimer and imaging studies were carried out to confirm the diagnosis.

RESULTS

A total of 101 patients suspected of having PTE underwent D-dimer level estimation and imaging studies for PTE. Sixty-eight of these had negative findings) on D-dimer assay. All these patients with negative findings on D-dimer assay had negative findings on pulmonary imaging studies also. So this test is very sensitive with very high negative predictive value (NPV). Whereas, 17 out of 33 patients positive for D-dimer, had positive findings on imaging studies, indicating a relatively less specific test.

CONCLUSION

Clinical assessment in combination with D-dimer assay can be used for timely differentiation of PTE from other conditions such as high altitude pulmonary oedema (HAPO) especially at isolated high altitude areas/military posts, so that patients could be evacuated as early as possible by fastest means to save the precious lives and in hospital settings this test identifies patients to whom anticoagulant therapy should not be given or patients who should not be subjected to invasive imaging tests.

Cost-effectiveness of strategies for diagnosing pulmonary embolism among emergency department patients presenting with undifferentiated symptoms

STUDY OBJECTIVE

Symptoms associated with pulmonary embolism can be nonspecific and similar to many competing diagnoses, leading to excessive costly testing and treatment, as well as missed diagnoses. Objective studies are essential for diagnosis. This study evaluates the cost-effectiveness of different diagnostic strategies in an emergency department (ED) for patients presenting with undifferentiated symptoms suggestive of pulmonary embolism.

METHODS

Using a probabilistic decision model, we evaluated the incremental costs and effectiveness (quality-adjusted life-years gained) of 60 testing strategies for 5 patient pretest categories (distinguished by Wells score [high, moderate, or low] and whether deep venous thrombosis is clinically suspected). We performed deterministic and probabilistic sensitivity analyses.

RESULTS

In the base case, for all patient pretest categories, the most cost-effective diagnostic strategy is to use an initial enzyme-linked immunosorbent assay D-dimer test, followed by compression ultrasonography of the lower extremities if the D-dimer is above a specified cutoff. The level of the preferred cutoff varies with the Wells pretest category and whether a deep venous thrombosis is clinically suspected. D-dimer cutoffs higher than the current recommended cutoff were often preferred for patients with even moderate and high Wells categories. Compression ultrasonography accuracy had to decrease below commonly cited levels in the literature before it was not part of a preferred strategy.

CONCLUSION

When pulmonary embolism is suspected in the ED, use of an enzyme-linked immunosorbent assay D-dimer assay, often at cutoffs higher than those currently in use (for patients in whom deep venous thrombosis is not clinically suspected), followed by compression ultrasonography as appropriate, can reduce costs and improve outcomes.

The value of ischemia-modified albumin compared with d-dimer in the diagnosis of pulmonary embolism

Study objective

The primary aim of this study was to investigate whether IMA levels are helpful in the diagnosis of pulmonary embolism (PE). The secondary aim was to determine whether IMA was more effective alone or in combination with clinical probability scores in the diagnosis of PE. Thirdly, the sensitivity and specificity of IMA is compared with D-dimer both with and without clinical probability scores in patients with suspected PE.

Methods

Consecutive patients presenting to the emergency department with suspected PE were prospectively recruited, and healthy volunteers were also enrolled as controls. D-dimer and IMA levels were measured for the entire study group. Wells and Geneva scores were calculated and s-CTPA was performed on all suspected PE patients.

Results

The study population consisted of 130 patients with suspected PE and 59 healthy controls. Mean IMA levels were 0.362 ± 0.11 ABSU for Group A, the PE group (n = 75); 0.265 ± 0.07 ABSU for Group B, the non-PE group (n = 55); and 0.175 ± 0.05 ABSU for Group C, the healthy control group (p < 0.0001). At a cut-off point of 0.25 ABSU, IMA was 93% sensitive and 75% specific in the diagnosis of PE. PPV was 79.4% and NPV was 78.6%. Mean D-dimer levels were 12.48 ± 10.88 μg/ml for Group A; 5.36 ± 7.80 μg/ml for Group B and 0.36 ± 0.16 μg/ml for Group C (p < 0.0001). The D-dimer cut-off point was 0.81 μg/ml with a sensitivity of 98.9% and a specificity of 62.7%, PPV of 69.4% and NPV of 83.3%. The use of IMA in combination with Wells and Geneva clinical probability scores was determined to have a positive impact on these scores' sensitivity and negative predictive values.

Conclusion

IMA is a good alternative to D-dimer in PE diagnosis in terms of both cost and efficiency. Used in combination with clinical probability scores, it has a similar positive effect on NPV and sensitivity to that of D-dimer. The PPV of IMA is better than D-dimer, but it is still unable to confirm a diagnosis of PE without additional investigation.

Value of quantitative D-dimer assays in identifying pulmonary embolism: implications from a sequential decision model

OBJECTIVES

To examine the cost-effectiveness of a quantitative D-dimer assay for the evaluation of patients with suspected pulmonary embolism (PE) in an urban emergency department (ED).

METHODS

The authors analyzed different diagnostic strategies over pretest risk categories on the basis of Wells criteria by using the performance profile of the ELISA D-dimer assay (over five cutoff values) and imaging strategies used in the ED for PE: compression ultrasound (CUS), ventilation-perfusion (VQ) scan (over three cutoff values), CUS with VQ (over three cutoff values), computed tomography (CT) angiogram (CTA) with pulmonary portion (CTP) and lower-extremity venous portion, and CUS with CTP. Data used in the analysis were based on literature review. Incremental costs and quality-adjusted-life-years were the outcomes measured.

RESULTS

Computed tomography angiogram with pulmonary portion and lower-extremity venous portion without D-dimer was the preferred strategy. CUS-VQ scanning always was dominated by CT-based strategies. When CTA was infeasible, the dominant strategy was D-dimer with CUS-VQ in moderate- and high-Wells patients and was D-dimer with CUS for low-Wells patients. When CTP specificity falls below 80%, or if its overall performance is markedly degraded, preferred strategies include D-dimer testing. Sensitivity analyses suggest that pessimistic assessments of CTP accuracy alter the results only at extremes of parameter settings.

CONCLUSIONS

In patients in whom PE is suspected, when CTA is available, even the most sensitive quantitative D-dimer assay is not likely to be cost-effective. When CTA is not available or if its performance is markedly degraded, use of the D-dimer assay has value in combination with CUS and a pulmonary imaging study. These conclusions may not hold for the larger domain of patients presenting to the ED with chest pain or shortness of breath in whom PE is one of many competing diagnoses.

Imaging for whom: patient or physician?

OBJECTIVE

Radiologic imaging examinations are being ordered beyond the margin of medical necessity. Radiologists can assess the value of imaging in a variety of clinical situations by gathering data regarding test ordering patterns and their effects on patient outcomes.

CONCLUSION

Emerging information technologies have the potential to facilitate the collection of data and permit the dissemination of appropriate guidelines to limit the number of unnecessary and possibly harmful examinations.

Clinical utility of D-dimer in patients with suspected pulmonary embolism and nondiagnostic lung scans or negative CT findings

BACKGROUND

The diagnosis of pulmonary embolism is difficult because the clinical diagnosis is nonspecific and all of the objective tests have limitations. The assay for plasma d-dimer may be useful as an exclusion test if results are negative. We conducted a prospective cohort study that evaluated the clinical utility (usefulness) of an automated quantitative d-dimer test in the diagnosis of patients with suspected pulmonary embolism.

METHODS

Consecutive eligible patients who had clinically suspected PE with nondiagnostic lung scans or negative helical CT scan of the chest results underwent d-dimer testing.

RESULTS

The d-dimer results were negative in 11 of 103 inpatients (10.6%, 95% confidence interval [CI], 5.5 to 18.3%) and 7 of 22 outpatients (31.8%, 95% CI, 13.9 to 54.9%; p = 0.02).

CONCLUSIONS

Measurement of plasma d-dimer is of limited clinical utility for inpatients with clinically suspected pulmonary embolism and nondiagnostic lung scans or negative helical CT results at a US academic health center.

Risk of Pulmonary Embolism After Negative MDCT Pulmonary Angiography Findings

OBJECTIVE

The purpose of our study was to determine the risk of pulmonary embolism in patients who have negative MDCT pulmonary angiography findings.

SUBJECTS AND METHODS

In this prospective study, one hundred two consecutive patients with suspected pulmonary embolism underwent MDCT pulmonary angiography. Scans were reviewed jointly by two observers and findings recorded by consensus. Observers noted whether pulmonary embolism or other disease was present. No pulmonary embolism was seen in 85 patients (52 men and 33 women; age range, 20-94 years; mean age, 60 years) who were followed up for a mean of 9 months (range, 4-13 months) for evidence of subsequent pulmonary embolism.

RESULTS

One patient had a diagnosis of pulmonary embolism made within 3 weeks of undergoing CT pulmonary angiography. MDCT pulmonary angiography showed additional potentially significant findings in 76% of patients; 47% of these findings were not suspected on chest radiography.

CONCLUSION

The risk of pulmonary embolism at a mean of 9 months after negative MDCT pulmonary angiography findings is 1%. In our study of patients without pulmonary embolism, MDCT pulmonary angiography revealed other causes for individual patients' signs or symptoms in most cases.

Venous thromboembolic disease: where does multidetector computed tomography fit?

Introduction of helical CT started a new era in the diagnosis of PE. It is noninvasive and readily available. Developments in helical CT technology (particularly introduction of multidetector scanners) improved image quality by decreasing the scanning time and slice thickness. With the addition of indirect CT venography to CT pulmonary angiography, CT also took the role of venous ultrasound, thus creating a single examination for diagnosis of VTD. On the other hand, CT is not perfect at all circumstances, especially in the evaluation of subsegmental arteries. Careful selection of patients for imaging studies will save time, cost, and radiation.

Misdiagnosis of pulmonary embolism in patients with allergic reaction — The importance of prior probability of disease

Because pulmonary embolism (PE) and its treatment carry substantial risk of morbidity and mortality, accurate diagnosis is essential. We report two cases with allergic reactions, in which PE was suggested by routine ECG and D-dimer elevation and strengthened by spiral CT. Therapy with low-molecular-weight heparin was initiated and long-term anticoagulation was considered. As their histories did not reveal any predisposing factor to PE, the cases were re-evaluated. Elevation of D-dimer was now attributed to allergic reaction, ECG abnormalities were considered as constitutional, and findings from spiral CT attributed to breathing artifacts and partial-volume effects. The diagnosis of PE was therefore rejected and anticoagulant treatment discontinued without sequelae. These cases show the importance of determining clinical probability before ordering further diagnostic tests and critical interpretation of test results suggestive of PE, based on prior probability of the disease.

CT for the diagnosis of venous thromboembolic disease

Spiral CT, venous ultrasound, ventilation-perfusion scanning, and D-dimer tests are routinely used in the diagnosis of venous thromboembolic disease. Advances in multidetector spiral CT and the combination of CT pulmonary angiography and venography as a one-step evaluation of venous thromboembolic disease have markedly improved detection of subsegmental emboli and deep pelvic venous thrombi and decreased the role of conventional pulmonary angiography. As CT has improved, many have questioned what "gold standard" CT should be compared with. Recent clinical outcome studies suggest that CT results are as good as pulmonary angiography and conventional imaging algorithms. Because the sensitivity of CT pulmonary angiography now exceeds 85%, it also appears that it is also more cost effective than other diagnostic approaches.

CT pulmonary angiography and suspected acute pulmonary embolism

PURPOSE

To evaluate the use and quality of CT pulmonary angiography in our department, and to relate the findings to clinical parameters and diagnoses.

MATERIAL AND METHODS

A retrospective study of 324 consecutive patients referred to CT pulmonary angiography with clinically suspected pulmonary embolism (PE). From the medical records we registered clinical parameters, blood gases, D-dimer, risk factors and the results of other relevant imaging studies.

RESULTS

55 patients (17%) had PE detected on CT. 39 had bilateral PE, and 8 patients had isolated peripheral PE. 87% of the examinations showing PE had satisfactory filling of contrast material including the segmental pulmonary arteries, and 60% of the subsegmental arteries. D-dimer test was performed in 209 patients, 85% were positive. A negative D-dimer ruled out PE detected at CT. Dyspnea and concurrent symptoms or detection of deep vein thrombosis (DVT), contraceptive pills and former venous thromboembolism (VTE) were associated with PE. The presence of only one clinical parameter indicated a negative PE diagnosis (p < 0.017), whereas two or more suggested a positive PE diagnosis (p < 0.002). CT also detected various ancillary findings such as consolidation, pleural effusion, nodule or tumor in nearly half of the patients; however, there was no association with the PE diagnosis.

CONCLUSION

The quality of CT pulmonary angiography was satisfactory as a first-line imaging of PE. CT also showed additional pathology of importance in the chest. Our study confirmed that a negative D-dimer ruled out clinically suspected VTE.

Laboratory tests in the diagnosis of pulmonary embolism

The diagnosis of pulmonary embolism (PE) requires objective testing. However, all imaging techniques have their own limitations and costs and cannot be performed in every patient with suspected PE. After decades of unfruitful research, several laboratory tests have been evaluated for suspected PE, the most promising being the D-dimer test. As a general rule, the specificity of D-dimers is too low to confirm PE. Conversely, several (but not all) D-dimer assays have a high sensitivity for diagnosing PE. Outcome studies indicate that the Vidas D-dimer and SimpliRED D-dimer can be used safely to withdraw anticoagulation when the pretest probability of PE is low (SimpliRED) or when it is low or moderate (Vidas). These results may however not apply to other D-dimer assays and clinicians should know the characteristics of the test used in their hospital. Blood gas analysis does not have sufficient sensitivity and specificity to confirm or exclude PE, but it may be used to evaluate the clinical probability of PE before other testing is done. The diagnostic value of the alveolar dead space fraction in patients with suspected PE is currently investigated. Initial data suggest that it needs to be combined with a D-dimer test to safely exclude PE. Brain natriuretic peptide and cardiac troponin have limited usefulness for diagnosing PE, but both tests may identify patients with a poor prognosis, in whom more aggressive treatment may be warranted.