Study designs of evaluations included in the review
Prospective studies of patients recruited consecutively were eligible for inclusion. Studies that were not performed prospectively, did not recruit participants consecutively, or did not provide the cut-off value for a negative D-dimer test result (unless qualitative tests were used), were included in a sensitivity analysis.
Specific interventions included in the review
Studies that used D-dimer to exclude PE or DVT were eligible for inclusion. The cut-off value for a negative D-dimer test result needed to be stated, unless qualitative tests were used. The D-dimer assays included in the review were enzyme-linked immunosorbent assay (ELISA), quantitative rapid ELISA, semi-quantitative rapid ELISA, qualitative rapid ELISA, quantitative latex agglutination, semi-quantitative latex agglutination, and whole blood agglutination assay.
Reference standard test against which the new test was compared
The reference standards used were compression ultrasonography, venography and impedance plethysmography in the included studies of DVT, and pulmonary angiography, ventilation-perfusion lung scanning and impedance plethysmography in the included studies of PE. The studies needed to interpret the results of the D-dimer and diagnostic tests for PE and DVT independently. Test descriptions needed to be sufficiently detailed to permit replication.
Participants included in the review
Studies with populations comprising a broad spectrum of patients were eligible for inclusion. The studies needed to include participants suspected of having PE or DVT, and all studies needed to include patients with or without disease to be included in the review.
Outcomes assessed in the review
Studies that used objective tests to diagnose PE or DVT were eligible for inclusion. Studies that provided the sensitivity and specificity, or the raw data for their calculation, were included.
How were decisions on the relevance of primary studies made?
Two reviewers assessed each study for inclusion. Any disagreements were resolved by discussion.