Performance and acceptability of self-collected specimens for diagnosis of rectal and pharyngeal Chlamydia trachomatis and Neisseria gonorrhoeae infections among men who have sex with men in China: a randomized controlled trial

Background: Extragenital Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections are prevalent among men who have sex with men (MSM). Self-sampling could potentially eliminate barriers to extragenital CT/NG testing for MSM that are hard to reach, who refuse to go for clinician-based testing, or who decline an examination. However, the required evidence to determine whether self-collected specimens are as accurate as clinician-taken specimens in terms of CT/NG diagnostic accuracy was limited in low and middle income countries. We therefore compared self-collected rectal and pharyngeal specimens with clinician-taken specimens for diagnostic accuracy among MSM in China.

Methods: This was a prospective convenience sample from 6 sexually transmitted infection (STI) clinics in China. We randomized the order of self-collected and clinician-taken specimens from the pharynx and rectum, plus first-void urine, for CT/NG detection. Self-sampling performance was compared with clinician-sampling as to agreement, sensitivity, and specificity. The acceptability of self-sampling was evaluated by questionnaire.

Results: Among the 325 participants, prevalences of rectal CT and NG infections were 13.6% and 5.2% and pharyngeal CT and NG prevalences were 1.5% and 2.8%, respectively. The agreements between the CT tests with the self-collected and clinician-taken specimens were 98.8% (κ = 0.95, 95% CI 0.89-1.00) for rectal site and 99.4% (κ = 0.83, 95% CI 0.60-1.00) for pharyngeal site; and the agreements between NG tests were 99.4% (κ = 0.94, 95% CI 0.86-1.00) for rectal site and 98.2% (κ = 0.72, 95% CI 0.50-0.93) for pharyngeal site. The sensitivity and specificity of self-collected swabs was as follows: rectal CT: 93.0% and 99.6%; pharyngeal CT: 100.0% and 99.4%; rectal NG: 100.0% and 99.4%; pharyngeal NG: 88.9% and 98.4%. Self-collection was highly acceptable, showing that 62.0% MSM preferred self-sampling over clinician-sampling; 90.2% would use self-sampling for detection of CT and NG again.

Conclusions: Extragenital screening for CT and NG should be recommended as part of STI services to MSM population. Self-collection of rectal and pharyngeal specimens had good performance for CT and NG tests and acceptability to the target population.

Trial registration: This trial was registered with the Chinese Clinical Trial Registry, ChiCTR2300073473. Registered 12/07/2023.