Swab-yourself Trial With Economic Monitoring and Testing for Infections Collectively (SYSTEMATIC): Part 1. A Diagnostic Accuracy and Cost-effectiveness Study Comparing Clinician-taken vs Self-taken Rectal and Pharyngeal Samples for the Diagnosis of Gonorrhea and Chlamydia.

BACKGROUND: Urogenital testing misses extragenital Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT). Extragenital self-sampling is frequently undertaken despite no robust randomized, controlled trial evidence of efficacy. We compared clinician-taken rectal and pharyngeal samples with self-taken samples for diagnostic accuracy and cost in men who have sex with men (MSM) and in females. METHODS: This was a prospective convenience sample from a UK sexual health clinic. We randomized the order of clinician- and self-taken samples from the pharynx and rectum, plus first catch urine (MSM) and vulvovaginal swabs (females), for NG/CT detection. RESULTS: Of 1793 participants (1284 females, 509 MSM), 116 had NG detected (75 urogenital, 83 rectum, 72 pharynx); 9.4% infected females and 67.3% MSM were urogenital-negative. A total of 276 had CT detected (217 urogenital, 249 rectum, 63 pharynx); 13.1% infected females and 71.8% MSM were urogenital-negative. Sexual history did not identify those with rectal infections. There was no difference in diagnostic accuracy between clinician- and self-taken samples from the rectum or pharynx. Clinicians took swabs more quickly than participants, so costs were lower. However, in asymptomatic people, nonqualified clinicians would oversee self-swabbing making these costs lower. CONCLUSIONS: There was no difference in the diagnostic accuracy of clinician-taken compared with self-taken extragenital samples. Sexual history did not identify those with rectal infections, so individuals should have extragenital clinician- or self-taken samples. Clinician-taken swabs cost less than self-taken swabs; however, in asymptomatic people or those who perform home testing, the costs would be lower than for clinician-taken swabs. CLINICAL TRIALS REGISTRATION: NCT02371109.

Swab-Yourself Trial With Economic Monitoring and Testing for Infections Collectively (SYSTEMATIC): Part 2. A Diagnostic Accuracy and Cost-effectiveness Study Comparing Rectal, Pharyngeal, and Urogenital Samples Analyzed Individually, Versus as a Pooled Specimen, for the Diagnosis of Gonorrhea and Chlamydia.

BACKGROUND: Sexual history does not accurately identify those with extragenital Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT), so universal extragenital sampling is recommended. Nucleic acid amplification tests (NAATs) are expensive. If urogenital, plus rectal and pharyngeal, samples are analyzed, the diagnostic cost is trebled. Pooling samples into 1 NAAT container would cost the same as urogenital samples alone. We compared clinician triple samples analyzed individually with self-taken pooled samples for diagnostic accuracy, and cost, in men who have sex with men (MSM) and females. METHODS: This was a prospective, convenience sample in United Kingdom sexual health clinic. Randomized order of clinician and self-samples from pharynx, rectum, plus first-catch urine (FCU) in MSM and vulvovaginal swabs (VVS) in females, for NG and CT detection. RESULTS: Of 1793 participants (1284 females, 509 MSM), 116 had NG detected (75 urogenital, 83 rectum, 72 pharynx); 276 had CT detected (217 urogenital, 249 rectum, 63 pharynx). There was no difference in sensitivities between clinician triple samples and self-pooled specimens for NG (99.1% and 98.3%), but clinician samples analyzed individually identified 3% more chlamydia infections than pooled (99.3% and 96.0%; P = .027). However, pooled specimens identified more infections than VVS/FCU alone. Pooled specimens missed 2 NG and 11 CT infections, whereas VVS/FCU missed 41 NG and 58 CT infections. Self-taken pooled specimens were the most cost-effective. CONCLUSIONS: FCU/VVS testing alone missed many infections. Self-taken pooled samples were as sensitive as clinician triple samples for identifying NG, but clinician samples analyzed individually identified 3% more CT infections than pooled. The extragenital sampling was achievable at no additional diagnostic cost to the FCU/VVS. CLINICAL TRIALS REGISTRATION: NCT02371109.