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New Rapid Chlamydia Test

Point-of-service diagnosis and treatment

Chlamydia trachomatis infection is the most prevalent sexually transmitted infection worldwide; thus, rapid detection and treatment are crucial to prevent further transmission. Investigators assessed the performance of the Chlamydia Rapid Test (an immunoassay) using self-collected vaginal swab specimens from 1349 women (age range, 16–55) at three sexual health centers and genitourinary clinics in Great Britain. The gold standard of comparison was polymerase chain reaction testing of first-void urine specimens.

The sensitivity and specificity of the Chlamydia Rapid Test were both high (83.5% and 98.9%, respectively). The positive predictive value of the test was 86.7%, and the negative predictive value approached 99%. The Chlamydia Rapid Test performed equally well in self-collected versus clinician-collected vaginal swab specimens; moreover, the sensitivity and specificity of the test did not significantly differ from that of PCR-based urine testing. Most participants found self-collection of vaginal swabs to be acceptable, and three quarters were willing to wait 30 minutes to 2 hours for the test results.

Comment: The Chlamydia Rapid Test has good sensitivity and specificity and can yield a result in 30 minutes. In-clinic identification of chlamydia infection decreases the risk for transmission by allowing immediate treatment and potentially bettering partner notification and tracing. However, the Rapid Test’s positive predictive value of 86% means that some cases will be missed; thus, patients with mucopurulent cervical discharge should be strongly considered for treatment regardless of a negative test result. The test’s overall advantages, combined with its ease of performance, could improve chlamydia screening in many settings — especially when PCR is unavailable.

— Wendy S. Biggs, MD

Published in Journal Watch Women's Health December 13, 2007

Citation(s):

Mahilum-Tapay L et al. New point of care Chlamydia Rapid Test — Bridging the gap between diagnosis and treatment: Performance evaluation study. BMJ 2007 Dec 8; 335:1190.

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