Comparing two methods of detection for Chlamydia trachomatis in liquid-based Papanicolaou tests

This study compared the performance of Chlamydia trachomatis testing using 2 methods: the BD ProbeTec Chlamydia trachomatis Q(x) Amplified DNA Assay (CTQ) on the BD Viper System with XTR technology (CTQ assay) and the Hybrid Capture (HC) 2 assay. A total of 1,054 Surepath and ThinPrep specimens were tested for C trachomatis nucleic acids using the CTQ assay and the HC2 assay. For positive and discrepant C trachomatis test results, confirmatory test for C trachomatis was performed using a reverse transcriptase-polymerase chain reaction. Of 1,054 liquid-based gynecologic cytology samples tested for C trachomatis using both assays, 1,041 tested negative on both. In 6 (0.57%) samples, findings were discordant. The CTQ assay and the HC2 assay had sensitivity rates of 100% and 66.7%, respectively, with comparable specificity (99.9%). The positive predictive values were 92.3% and 88.9% with the CTQ and HC2 assays, respectively. In this study, the CTQ assay was found to be more sensitive than the HC2 assay in detecting chlamydial infection; the CTQ assay also demonstrated a higher positive predictive value.