Relative Accuracy of Nucleic Acid Amplification Tests and Culture in Detecting Chlamydia in Asymptomatic Men

Abstract

Published estimates of the sensitivity and specificity of PCR and ligase chain reaction (LCR) for detecting Chlamydia trachomatis are potentially biased because of study design limitations (confirmation of test results was limited to subjects who were PCR or LCR positive but culture negative). Relative measures of test accuracy are less prone to bias in incomplete study designs. We estimated the relative sensitivity (RSN) and relative false-positive rate (RFP) for PCR and LCR versus cell culture among 1,138 asymptomatic men and evaluated the potential bias of RSN and RFP estimates. PCR and LCR testing in urine were compared to culture of urethral specimens. Discordant results (PCR or LCR positive, but culture negative) were confirmed by using a sequence including the other DNA amplification test, direct fluorescent antibody testing, and a DNA amplification test to detect chlamydial major outer membrane protein. The RSN estimates for PCR and LCR were 1.45 (95% confidence interval [CI] ‫؍‬ 1.3 to 1.7) and 1.49 (95% CI ‫؍‬ 1.3 to 1.7), respectively, indicating that both methods are more sensitive than culture. Very few false-positive results were found, indicating that the specificity levels of PCR, LCR, and culture are high. The potential bias in RSN and RFP estimates were <5 and <20%, respectively. The estimation of bias is based on the most likely and probably conservative parameter settings. If the sensitivity of culture is between 60 and 65%, then the true sensitivity of PCR and LCR is between 90 and 97%. Our findings indicate that PCR and LCR are significantly more sensitive than culture, while the three tests have similar specificities.

Prevalence of Chlamydia trachomatis in human immunodeficiency virus-infected women in Cuba

“…Other authors have compared for accuracy several methods like tissue culture or antigen detection with PCR and all of them have obtained excellent results with the latter, which has proven to have more sensitivity than tissue culture. It is also in agreement with the results that we obtained when our nested PCR was normalized (Cheng et al 2001). …”

Performance value of high risk factors in colorectal cancerscreening in China

“…To the best of our knowledge, the current study is the first analysis comparing the performance value of high risk factors in mass CRC screening in China. Because confirmatory examination was limited to subjects who had at least one positive test, studies calculated the RSN and relative false-positive rate in comparing the 2 screening methods [16,17] . Colorectal adenomatous polyps are recognized as precancerous lesions and are responsible for most cases of CRC [18] .…”

A comparison of clinical features between chlamydial and non-chlamydial urethritis in men negative for gonococcal infection who attended a urological outpatient clinic in Japan

“…In this series, of 194 patients who were negative for Neisseria gonorrhoeae, 96 and 98 were [6,7]. The incubation period in the CU group was significantly longer than that in the NCU group, and the incidence of comparatively severe symptoms, such as urethral discharge and burning on urination, was significantly greater in the NCU group than in the CU group.…”