Self-sampling for STIs in rectum and throat just as accurate

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Self-sampling for sexually transmitted infections (STIs) in the rectum and throat is just as accurate as testing performed by a healthcare worker, investigators from Leeds report.

This is based on a study that involved women and gay men, Aidsmap reports. The research found that rectal and throat self-sampling was equal in accuracy to sampling by healthcare workers. Self-sampling also had cost-savings potential, especially when performed at home.

A large number of rectal infections were identified in individuals who did not report a history of anal sex. The investigators, led by Dr Janet Wilson of Leeds Teaching Hospitals, therefore recommend screening both women and gay men for rectal and throat infections irrespective of reported sexual activity.

“We demonstrated good concordance between the clinician and self-taken samples with no difference in diagnostic accuracy,” write the authors. “As sexual history does not identify those with extragenital infections, our study strongly supports the existing evidence for universal sampling in both men who have sex with men and females undergoing chlamydia and gonorrhoea testing.”

An accompanying editorial acknowledges the findings regarding the accuracy of self-sampling. However, it adopts a more sceptical stance concerning the health and economic benefits of universal screening of women and gay men for bacterial STIs in the rectum and throat.

Wilson and her colleagues, therefore, believe that their findings have important implications for policymakers and STI services, showing that self-sampling for infections in the throat and rectum yields highly accurate results. Moreover, they believe their findings strongly support screening all gay men and women for STIs in the throat and rectum during sexual health check-ups.

An accompanying editorial by Dr Noah Kojima and Dr Jeffrey Klausner and University of California-Los Angeles describes the study as “valuable” and praises its methodology.

Abstract 
Background: Urogenital testing misses extragenital Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT). Extragenital self-sampling is frequently undertaken despite no robust RCT evidence of efficacy. We compared clinician-taken rectal and pharyngeal samples with self-taken samples for diagnostic accuracy and cost in MSM and females.
Methods: Prospective, convenience, sample in UK sexual health clinic. Randomised order of clinician and self-samples from 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 site, 83 rectum, 72 pharynx); 9.4% infected females and 67.3% MSM were urogenital negative. 276 had CT detected (217 urogenital site, 249 rectum, 63 pharynx); 13.1% infected females and 71.8% MSM were urogenital negative. Sexual history did not identify those with rectal infections. Clinician-rectal and self-rectal positive percent agreements (PPA) for NG detection were 92.8% and 97.6%; clinician-rectal, and self-rectal PPA for CT detection were 95.6% and 97.2%. There was no difference in diagnostic accuracy between clinician and self-taken samples.
Clinicians performed swabs quicker than participants so costs were lower. However, in asymptomatic people, non-qualified clinicians would oversee self-swabbing and these costs would be lower than clinician’s.
Conclusions: There was no difference in diagnostic accuracy of clinician 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 swabs cost less than self-swabs but in asymptomatic people, or doing home testing, their costs would be lower than clinician swabs.

Authors
Janet D Wilson, Harriet E Wallace, Michelle Loftus-Keeling, Helen Ward, Bethan Davies, Armando Vargas-Palacios, Claire Hulme, Mark H Wilcox

 

Full Aidsmap report

 

Clinical Infectious Diseases abstract

 

Clinical Infectious Diseases editorial commentary

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