A Cochrane review[Abstract] 1 included 4 studies with a total of 1 585 adults. The aim of the review was to investigate the ability of the D-dimer test to rule out a diagnosis of acute pulmonary embolism (PE) in patients treated in hospital outpatient and accident and emergency settings who have had a pre-test probability of PE determined according to a clinical prediction rule (CPR). CPRs used were Geneva (including Revised and Revised Simplified), Wells (two-level, three-level and simplified) and the Charlotte rule. Studies used pulmonary angiography, V/Q scintigraphy, selective pulmonary angiography (CTPA) and magnetic resonance pulmonary angiography (MRPA) as reference standard tests. Quantitative D-dimer assays demonstrated high sensitivity in all 4 studies, but with high levels of false-positive results, especially among those over the age of 65 years. Estimates of sensitivity ranged from 80% to 100%, and estimates of specificity from 23% to 63%. Among persons with low or intermediate pre-test probability of PE according to CPR, sensitivity of D-dimer tests ranged from 94% to 100%.
A systematic review 2 included 78 studies, of which 31 directly compared an ELISA with other D-dimer assays. Overall prevalence was 36% for deep venous thrombosis (DVT) and 25% for pulmonary embolism (PE). For the diagnosis of DVT, the sensitivity of the ELISA and quantitative rapid ELISA was higher than of semiquantitative or quantitative latex agglutination assays (95-96% vs. 79-86%). ELISAs had negative likelihood ratios of 0.10-0.25. For the diagnosis of PE, the ELISA and quantitative rapid ELISA were more sensitive than semiquantitative latex (96-97% vs. 80-89%). ELISAs had negative likelihood ratios of 0.7-0.18. The sensitivity of whole blood D-dimer assay was 86% and 83%, respectively. For the diagnosis of DVT, the specificity of ELISAs was 40-44% and of latex assays 61-66%. For the diagnosis of PE, specificities were 41-51% and 47-56%, respectively.Commentary: Negative results on an ELISA or quantitative rapid ELISA reliably exclude a diagnosis of venous thromboembolism, at least in patients with low to moderate pretest probability of disease (<30%). For excluding PE or DVT, a negative result on quantitative rapid ELISA is as diagnostically useful as a normal lung scan or negative duplex ultrasonography finding.
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