Study designs of evaluations included in the review
No inclusion criteria relating to study design were specified.
Specific interventions included in the review
Studies of D-dimer tests for the diagnosis of DVT or PE were eligible for inclusion. No details relating to the assay method or cut-off point were specified in the inclusion criteria. The D-dimer test is used to detect the presence of plasmin-mediated degradation products of fibrin that contain cross-linked D fragments. The D-dimer test methodologies used in the 13 studies which formed the basis of the primary analysis in this review were: latex agglutination tests (cut-off values, where specified, 200 to 1,500 ng/mL); enzyme-linked immunosorbent assays (ELISA; cut-off values 25 to 550 ng/mL); and immunofiltration (cut-off point 500 ng/mL); whole blood agglutination (no cut-off point specified).
Reference standard test against which the new test was compared
The included studies were required to compare D-dimer test results with those of objective diagnostic tests for DVT or PE; no specific reference standard was described in the inclusion criteria. However, the assessment of the methodological standard of the primary studies included three elements requisite for a study to be included in the review's primary analysis. One of these elements specified that the reference standard should be venography, pulmonary angiography, V/Q lung scanning with clinical correlation, or lower extremity ultrasonography with clinical correlation.
Participants included in the review
No inclusion criteria were specified in relation to the patient characteristics. However, the assessment of the methodological standard of the primary studies included three elements requisite for a study to be included in the review's primary analysis. One of these elements specified that the study participants should represent the complete spectrum of patients with suspected DVT or PE, including those with and without disease.
Outcomes assessed in the review
No inclusion criteria were specified with respect to the outcome measures. Test sensitivity and specificity were the outcome measures reported in the review, and these were illustrated using receiver operating characteristic (ROC) curves.
How were decisions on the relevance of primary studies made?
The authors do not state how the papers were selected for review, or how many of the reviewers performed the selection.