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SimpliRed d-dimer assay in suspected pulmonary embolus
  1. Magnus Harrison,
  2. Steve Jones
  1. Department of Emergency Medicine, Manchester Royal Infirmary, Oxford Road, Manchester M139WL

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    Report by Magnus Harrison, Research Fellow Search checked by Steve Jones, Research Fellow

    Clinical scenario

    A 40 year old man presents with acute suspected pulmonary embolus (PE). You wonder whether a negative SimpliRed d-dimer assay is sufficient to rule out the diagnosis of PE.

    Three part question

    In [a patient suspected of having an acute pulmonary embolus] is [a negative SimpliRed d-dimer assay] able to [rule out PE]?

    Search strategy

    Medline 1966–07/00 using the OVID interface. [{(Exp pulmonary embolism or pulmonary OR {( AND (exp embolism OR embolism$.mp.)} OR (exp thromboembolism or] AND (Simplired$ OR exp fibrin fibrinogen degredation products or d-dimer$.mp)].

    Search outcome

    Altogether 172 papers were found of which 162 were irrelevant and six of insufficient quality for inclusion. The remaining four papers are shown in table 4.

    Table 4


    The “gold standard” investigation for the diagnosis of PE is pulmonary angiography. However, the universal application of this investigation in all patients, in any clinical trial for the investigation of PE, is unethical; the morbidity and mortality associated with this investigation are unacceptably high. Therefore most research is conducted using decision making analysis tools; this would be acceptable if all study patients are subject to the same diagnostic tests. If this does not happen, the validity of the results can be questioned. In the above trials, where the confidence intervals are given, the width of the interval is large; this could be remedied with a larger more powerful trial. As they stand, the confidence intervals are too wide.

    Clinical bottom line

    SimpliRed does not have the required sensitivity to be used to rule out PE in an ED setting.

    Report by Magnus Harrison, Research Fellow Search checked by Steve Jones, Research Fellow