D-Dimer Tests for Assessment of Patients With Suspected Pulmonary Embolism

Abstract

mote and recent history of the naming of medical specialties and the continued disagreement concerning the desirability of even the term internal medicine, I would think that medical journals would be in the forefront of suggesting the use of existing terms that are clear and unambiguous. Furthermore, I would think that most children of the pertinent age group would rather make a visit to their family ephebiatrician than to their adolescent medicine doctor. This is in contrast to a recent article by Larsen and colleagues, 2 who assessed the reliability of the same D-dimer assay (Table). Using the discriminant values suggested by the manufacturer, the VIDAS kit has a sensitivity of 90%, a specificity of 42%, and an NPV of 85%. The reason for this discrepancy is unclear. N. Ralph Frankel, MDHowever, the article by Kruip et al 1 raised some excellent points. Accurate diagnosis of deep vein thrombosis (DVT) and correct therapy are of vital importance to reduce the risk of long-term morbidity or mortality due to pulmonary embolism. As clinical signs and symptoms are nonspecific, DVT must be confirmed by objective methods.3 At present, most hospitals use the noninvasive compression ultrasonography as the gold standard, with high sensitivity and specificity for proximal DVT, whereas the sensitivity for calf vein thrombosis is lower. [4][5][6][7] Several strategies for the exclusion of DVT have been suggested elsewhere.8 One study used the standard VIDAS D-dimer assay as the initial screening in 474 patients with suspected DVT, combined with ultrasonography. 9 This combined strategy could demonstrate an NPV of 99.3% in a population with a low prevalence of venous thromboembolism of 23%.Using the reversed strategy, that is, ultrasonography as the initial screening method combined with a D-dimer assay, another study of 476 patients with DVT revealed a prevalence of 27.5% and an NPV of 99.6%. 10This calls for a differential strategy; in cases of low clinical probability, the initial test could be a D-dimer test with a high NPV.11 In cases with a high clinical probability of disease, a test with a high positive predictive value should be chosen, such as ultrasonography.Finally, one should be aware that many systemic disorders can influence levels of D-dimer, and high levels have been reported in diseases as diverse as atrial fibrillation, congestive heart failure, peripheral artery disease, and cancer-indeed, D-dimer has been considered as a useful clinical marker of thrombogenesis and abnormal levels may also have prognostic implications for cardiovascular events.

Utilidad del dímero-D por ELISA rápido en el diagnóstico de la embolia pulmonar en un servicio de urgencias

“…Los métodos de detección son variados y con distintos resultados. Las técnicas de aglutinación de látex, incluso de segunda generación, han resultado poco sensibles para descartar de forma fiable una tromboembolia pulmonar 10 . La técnica ELISA clásica tiene una elevada sensibilidad, pero es compleja, lenta de realizar y poco práctica en un servicio de urgencias 7,[16][17][18][19] .…”

“…La técnica ELISA clásica tiene una elevada sensibilidad, pero es compleja, lenta de realizar y poco práctica en un servicio de urgencias 7,[16][17][18][19] . Los tests semicuantitativos con aglutinación de látex son rápidos, sencillos y más baratos, pero presentan una sensibilidad limitada (83%) y un valor predictivo negativo del 90% para la embolia pulmonar 10 , por lo que no se recomiendan como prueba para excluir de forma fiable esta entidad 3,10,19 . Algunos autores han referido que la técnica de ELISA rápido (VIDAS) es un método cuantitativo rápido, automático, que emplea reactivos preparados unidosis para su uso inmediato 7,18,[20][21][22] .…”

“…Su positividad es muy inespecífica y puede encontrarse en la enfermedad tromboembólica venosa y otros procesos patológicos: insuficiencia cardíaca, cirugía, infecciones, conectivopatías y cáncer 10,11 . Sus valores de detección dependen de muchas variables (especialmente comorbilidad, sedentarismo, paciente ambulatorio hospitalizado, tamaño del trombo, tratamiento anticoagulante y día de estudio tras el accidente) y del método utilizado para su medición 7 .…”