New point of care Chlamydia Rapid Test--bridging the gap between diagnosis and treatment: performance evaluation study

Abstract

Objective: To evaluate the performance of a new Chlamydia Rapid Test with vaginal swab specimens as a potential tool for chlamydia diagnosis and screening.

Design: Performance evaluation study. Settings A young people's sexual health centre (site 1) and two genitourinary medicine clinics (sites 2 and 3) in the United Kingdom.

Participants: 1349 women aged between 16 and 54 attending one of the three clinics.

Main outcome measures: Sensitivity, specificity, positive predictive value, and negative predictive value of the Chlamydia Rapid Test versus polymerase chain reaction and strand displacement amplification assays; correlation between the Chlamydia Rapid Test visual signal and organism load; acceptability to participants of self collected vaginal swabs as the specimen type for Chlamydia testing.

Results: Polymerase chain reaction positivity rates for Chlamydia trachomatis infection were 8.4% (56/663) at site 1, 9.4% (36/385) at site 2, and 6.0% (18/301) at site 3. Compared with polymerase chain reaction assay, the resolved sensitivity, specificity, positive predictive value, and negative predictive value of the Chlamydia Rapid Test were 83.5% (91/109), 98.9% (1224/1238), 86.7% (91/105), and 98.6% (1224/1242). Compared with strand displacement amplification assay, sensitivity and specificity of the Chlamydia Rapid Test were 81.6% (40/49) and 98.3% (578/588). Organism load of self collected vaginal swabs ranged from 5.97x10(2) to 1.09x10(9) Chlamydia plasmids per swab, which correlated well with the Chlamydia Rapid Test's visual signal (r=0.6435, P<0.0001). Most (95.9%) surveyed participants felt comfortable about collecting their own swabs.

Conclusions: The performance of the Chlamydia Rapid Test with self collected vaginal swabs indicates that it would be an effective same day diagnostic and screening tool for Chlamydia infection in women. The availability of Chlamydia Rapid Test results within 30 minutes allows for immediate treatment and contact tracing, potentially reducing the risks of persistent infection and onward transmission. It could also provide a simple and reliable alternative to nucleic acid amplification tests in chlamydia screening programmes.

Fig 1 Recruitment and testing algorithm for study participants. CCVS=clinician collected vaginal swab specimens; CRT=Chlamydia Rapid Test; PC=procedural control; PCR=polymerase chain reaction; SDA=strand displacement amplification assay; SCVS=self collected vaginal swab specimens

Fig 2 Chlamydia trachomatis (CT) organism load by quantitative polymerase chain reaction (qPCR; plasmids/swab) (n=33, r=0.644, P<0.0001). CRT=Chlamydia Rapid Test