COMPARISON OF 4 RAPID D-DIMER TESTS FOR DIAGNOSIS OF PULMONARY-EMBOLISM

Aim of this study was to evaluate rapid D-Dimer tests for their utilit y in diagnosis of acute pulmonary embolism (PE). Tests were performed in 183 consecutive pats referred for lung scanning because of clinical ly suspected PE. According to lung scans and the clinical course of di sease 19 pats were classified to have PE with high probability and 164 with low probability. An ELISA (Agen) was used as the D-Dimer referen ce and results compared with those of a turbidimetric (Behring), an im munofiltration (Nycomed), latex plasma and whole blood agglutination t est (both Agen). There was a poor correlation between the turbidimetri c test and either the ELISA (R=0.38) and immunofiltration test (R=0.49 ). The correlation between the ELISA and immunofiltration test was bet ter (R=0.73). The qualitative latex and whole blood agglutination test s were better fitted to ELISA since positive and negative samples were overlapped only in their Ist and 9th percentiles of ELISA values. The whole blood agglutination test was positive at lower ELISA values tha n the latex test. The highest sensitivity test for PE was the immunofi ltration test (95%) (500ng/mL cut-off), followed by the turbidimetric method (89%) (66ng/mL), the ELISA (89%) (300ng/mL), the whole blood te st (88%) and the latex test (68%). Specificity was lowest for the immu nofiltration test (33%), intermediate (57-65%) for the turbidimetric a nd whole blood agglutination tests, and highest for the ELISA and the most insensitive latex test (76/77%). The whole blood assay was found to be the fastest and most suitable for bed site testing but weak posi tives were difficult to read. The immunofiltration test required plasm a preparation but allowed objective semiquantitation of results. The l ess rapid turbidimetric assay was fully quantitative and objective.