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

• Published in: Clinical infectious diseases 2021-11, Vol.73 (9), p.e3172-e3180
• Main Authors: Wilson, Janet D, Wallace, Harriet E, Loftus-Keeling, Michelle, Ward, Helen, Davies, Bethan, Vargas-Palacios, Armando, Hulme, Claire, Wilcox, Mark H
• Format: Article
• Language: English
• ISSN: 1058-4838; 1537-6591
• DOI: 10.1093/cid/ciaa1266

Abstract 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. Extragenital selfsampling for Neisseria gonorrhoeae and Chlamydia trachomatis is frequently undertaken despite no robust evidence of its efficacy. In this randomized, powered study, we found no difference in diagnostic accuracy between clinician- and self-taken rectal and pharyngeal samples.