Reproducibility of the Roche Amplicor Polymerase Chain Reaction Assay for Detection of Infection by Chlamydia Trachomatis in Endocervical Specimens (Technical Briefs‪)‬

Several investigators have reported that the Roche Amplicor [TM] PCR assay for detection of infection by Chlamydia trachomatis in endocervical specimens (Roche Diagnostic Systems) has a sensitivity in the range of 89-97% (1-8), although a few studies have found lower sensitivity, in the range of 64-86% (8-10). All of the referenced studies have reported a specificity of 99-100%. Recently, however, the reproducibility of the assay has been questioned by investigators who found that 13 of 35 cervical specimens that were tested and then retested with the assay showed great variability in absorbance values (11). Because there is a paucity of information available concerning the reproducibility of the Amplicor assay, we report herein data informative on the issue that were obtained at UMDNJ-University Hospital. The protocol for this study was approved by the Institutional Review Board of UMDNJ-New Jersey Medical School. The reproducibility studies reported here were derived from two data sets. The first set, 162 specimens, was drawn from a consecutive series of 5011 endocervical specimens examined by the Amplicor assay for detection of C. trachomatis (Table 1). This series was begun on January 18, 1994, and extended to May 27, 1994. The second data set, consisting of 717 specimens collected during various periods extending from May 31, 1994, to October 31, 1995, provided additional samples with differing quantitative assay absorbance values ([A.sub.450]) on initial examination. In all, 879 specimens (162 + 717) were used to assess reproducibility of the assay. Three types of reproducibility studies were performed: 571 specimens that were either positive or negative on initial testing were subjected to duplicate-repeat testing on a subsequent day; 79 specimens with initially equivocal results ([A.sub.450], 0.2-0.5) were subjected to duplicate-repeat testing in triplicate (three sets of duplicate-repeat tests) to test the manufacturer's algorithm for resolving the status of equivocal results; and a separate group of 229 specimens was subjected to within-run triplicate testing. Within each of the several absorbance categories that were established and that are defined in Table 1, the specimens tested for reproducibility were randomly chosen.