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D-dimer in patients with clinically suspected pulmonary embolism
J S Ginsberg1, P A Brill-Edwards, C Demers
1Department of Medicine, McMaster University, Hamilton, Canada.
Chest
|December 1, 1993
Summary
The enzyme-linked immunosorbent assay (ELISA) D-dimer test can exclude pulmonary embolism (PE) but has low specificity. The latex agglutination assay shows potential for excluding PE in specific patients but requires further large-scale clinical trials.
Area of Science:
- Clinical diagnostics
- Biomedical engineering
- Medical imaging
Background:
- Pulmonary embolism (PE) diagnosis relies on clinical suspicion and imaging.
- D-dimer assays are used to help rule out PE, but their utility varies by assay type and cutoff.
- Enzyme-linked immunosorbent assay (ELISA) and latex agglutination assay are common D-dimer measurement methods.
Purpose of the Study:
- To evaluate the clinical usefulness of D-dimer measurements for diagnosing pulmonary embolism (PE).
- To compare the diagnostic performance of ELISA and latex agglutination assays for D-dimer in patients with suspected PE.
- To determine optimal cutoff values for D-dimer assays in the context of suspected PE.
Main Methods:
- A prospective cohort study was conducted with 221 consecutive patients suspected of having PE.
- D-dimer levels were measured using ELISA (300 ng/ml cutoff) and latex agglutination assay (500 ng/ml cutoff).
- Patients underwent ventilation/perfusion (V/Q) lung scanning, impedance plethysmography (IPG), and in some cases, pulmonary angiography for PE confirmation.
Main Results:
- The ELISA D-dimer assay (300 ng/ml cutoff) demonstrated 100% sensitivity and negative predictive value but low specificity (26%) for PE.
- The latex agglutination assay (500 ng/ml cutoff) showed 84% sensitivity and 93% negative predictive value in all patients.
- In patients with non-high-probability V/Q scans, the latex agglutination assay had 90% sensitivity and 98% negative predictive value, with 55% specificity.
Conclusions:
- An ELISA D-dimer result below 300 ng/ml can effectively exclude PE, though it occurs infrequently.
- The latex agglutination assay shows promise for excluding PE in patients with suspected PE and non-high-probability V/Q scans.
- Further large-scale clinical trials are necessary to confirm the sensitivity of the latex agglutination assay before its use in clinical decision-making for PE management.