With regard to D-dimer testing, the ICSI Technology Assessment Committee finds:
Many D-dimer assays are available; they are not equivalent. It is imperative that an assay is applied only to a population in which it has been clinically validated.
Many factors must be considered before ordering a D-dimer test including: the population to which it is being applied, the presence of comorbid conditions, the use of anti-coagulation therapy, and the length of symptoms. D-dimer testing is best used in an ambulatory care setting rather than for hospitalized patients.
D-dimer testing must be preceded by an assessment of clinical pre-test probability and the D-dimer assay results should be linked to the probability model results.
Selected D-dimer assays are highly sensitive. Therefore, a negative D-dimer can be used in combination with pretest probability to rule-out disease. However, D-dimer testing is highly non-specific. Therefore, a positive result should not be used to diagnose VTE.
For patients with suspected DVT, D-dimer testing, in the correct setting, has the potential to significantly decrease the need for initial and subsequent radiological investigation. (Conclusion Grade II)
The risks associated with a misdiagnosis of PE are typically more severe than those associated with a misdiagnosis of DVT. Higher negative predictive values are required to safely use D-dimer to exclude PE. The evidence, to date, suggests that current assays, with the possible exception of ELISA and rapid ELISA (VIDAS) methods, are not acceptable for use in excluding PE in patients with clinical suspicion of PE. (Conclusion Grade III)
D-dimer testing is a safe procedure requiring only a blood sample. However, false negative findings may result in insufficient patient follow-up and withholding of appropriate therapy. Misinterpretation of elevated D-dimer levels may lead to unnecessary invasive procedures and anticoagulation therapy.