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Self-testing kits for sexually transmitted infections (STIs) could increase diagnoses while reducing costs. In a new study, people took samples from 3 different sites in the body then pooled the 3 swabs in one container. The swabs were analysed in a single test for the common bacterial infections, gonorrhoea and chlamydia. 

The researchers concluded that sexual health services could consider providing at-home self-testing kits. They say self-testing may cause less embarrassment for service users, improve uptake, and free up clinicians’ time. 

These results come from the Swab-Yourself Trial with Economic Monitoring and Testing for Infections Collectively (SYSTEMATIC). In the first part of the trial, researchers found that people can take their own swabs as effectively as clinicians. They also showed that many infections would be missed by a single swab of the vagina or urine test. 

In the second part of the study, people collected their own 3 samples with self-testing kits. They placed the swabs in a single container. A single analysis of the pooled samples cost no more than the current single test.

Current services generally carry out a single test (of urine or a vaginal swab) for most people. They take extra swabs from the throat and rectum (triple-site screening) only for people in high-risk groups.

The research concluded that self-testing kits could be widely used. With this approach, samples from 3 sites in the body are then pooled for a single analysis. The researchers say these kits would allow services to offer triple-site screening to more service users. They would find far more gonorrhoea and chlamydia infections than the current single-site test.  

Further information on STIs can be found on the NHS website.

What’s the issue?

Gonorrhoea and chlamydia are the most common bacterial STIs in the UK and worldwide. They spread from person to person during sex or genital contact. 

Most people with chlamydia have no symptoms. Many with gonorrhoea also lack symptoms (around 1 in 10 men and almost 1 in 2 women). This means that infections may remain untreated. This can lead to serious, long-term health problems. In women, untreated infections can lead to pelvic inflammatory disease, which is painful and reduces fertility. In men, both infections can cause pain in the testicles. 

Gonorrhoea and chlamydia can infect the entrance to the womb (the cervix), the tube that passes urine out of the body (the urethra) and the rectum. The throat and eyes may also be infected

Standard tests take urine samples or swabs of the vagina or penis. It would be expensive to test everyone in all infection sites. Most national and international guidelines recommend also testing the rectum and throat (triple-site screening) only for groups at high risk:

  • men who have sex with men 
  • women who have received anal sex 
  • women who have given oral sex.

Research suggests that this approach misses infections. Women may not report anal or oral sex; and infections may have spread. But triple-site samples cost 3 times as much to analyse as single swabs. 

A solution would be for people to take their own samples from the 3 areas of their body and place them together in one container. Pooled triple-site samples should cost no more to analyse than a single sample.

Some sexual health services are already pooling triple-site samples, but there are concerns that this could reduce the accuracy of the test. A handful of studies have researched this approach in men who have sex with men, but none have looked in women. 

The SYSTEMATIC study aimed to work out whether triple-site pooling for women and men who have sex with men is a reliable way of diagnosing gonorrhoea and chlamydia. 

What’s new?

The SYSTEMATIC trial included 1,284 women and 509 men who have sex with men. All attended a sexual health clinic in Leeds. Some 116 (9%) tested positive for gonorrhoea; 276 (15%) for chlamydia.

The first part of the trial found that self-taken swabs of throat and rectum gave diagnoses as accurately as swabs taken by clinicians. The study also found that it was cheaper for people to take their own swabs at home than for clinicians to take the swabs in a clinic. 

It also found that many infections would have been missed by a single swab of the vagina or urine test. Single swabs missed 100 gonorrhoea and chlamydia infections out of a total of 392. Furthermore, the most common site for chlamydia infections in women was the rectum, regardless of whether they reported having anal sex. 

The second part of the SYSTEMATIC trial looked at the effect of pooling triple-site samples into one container for a single analysis. Samples were taken from throat and rectum for each individual. Plus, in women, from the vagina; and in men who have sex with men, from the urine. Self-taken samples were pooled (3 per person); swabs taken by clinicians were analysed in 3 separate tests. 

The study found that:

  • gonorrhoea was detected equally well by pooled and single swabs, both in women and men who have sex with men (both approaches picked up 98% infections) 
  • chlamydia was slightly less likely to be picked up in pooled swabs than in three separate tests (3% lower for women; 5% lower for men who have sex with men) and 13 infections were missed.

Although the detection rate for chlamydia was lower with pooled samples, it still picked up more than 90% infections, which is the recommended minimum. The researchers say the reduction in sensitivity for men who have sex with men could be due to urine diluting the sample.

In further research, the authors found that most participants (83% men who have sex with men; 77% women) strongly agreed or agreed that they felt confident taking their own swabs. People could take their own swabs in a clinic or at home using postal kits, which many prefer. This also saves time for clinicians.

Why is this important?

The SYSTEMATIC trial found that many infections are missed by the current single-site test. The researchers would like triple-site, pooled samples to be offered to all women and men who have sex with men. This would vastly reduce the number of missed infections. 

Pooled samples could introduce significant cost-savings. This matters because, even in high-income countries, publicly-funded health systems struggle to fund individually-tested triple-site swabs. This research demonstrates that sexual health services can save money by pooling triple-site samples from men who have sex with men while introducing routine triple-site testing for all women. 

Research from the SYSTEMATIC study shows that the sampling could be done either by a clinician or as a self-test. This would not make a difference to the accuracy of the test.  People may be less embarrassed if they can take their own swabs, and it frees up clinicians’ time. Postal kits allow people to take their own swabs at home, which may improve uptake of testing. Plus, self-taken swabs are cheaper than clinician-taken swabs if overseen by a healthcare assistant or performed at home. 

What’s next?

Since the trial, the authors have surveyed men who have sex with men to ask how they felt about accepting more missed chlamydia infections at large cost savings to the NHS. They found that most (more than 90%) would be happy with a test that detected 97% infections. 

The current test does not quite reach that threshold. SYSTEMATIC researchers are now exploring different pooling techniques, which could  increase the detection of chlamydia in men who have sex with men. The research team plans to use a smaller volume of urine, plus a swab of the urethra entrance, to avoid dilution of the sample. 

Some clinics have already introduced pooled triple-site samples taken by the individual. Advocacy groups may campaign for wider use of this approach.

You may be interested to read

This NIHR Alert is based on: Wilson JD, and others. 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 analysed individually, versus as a pooled specimen, for the diagnosis of gonorrhoea and chlamydia. Clinical Infectious Diseases 2020;73:9 

Sexual health information from the NHS

SXT: a digital service to signpost patients to their nearest, most appropriate healthcare provider. 

The earlier paper from the SYSTEMATIC study: Wilson JD, and others. Swab-yourself trial with economic monitoring and testing for infections collectively (SYSTEMATIC): Part 1. A diagnostic accuracy, and cost-effectiveness, study comparing clinician-taken versus self-taken rectal and pharyngeal samples for the diagnosis of gonorrhoea and chlamydia. Clinical Infectious Diseases 2020;73:9 

A poster presentation on extragenital sampling for chlamydia and gonorrhoea: Wallace H, and others. Self-taken extragenital sampling – what do women and MSM think? Feedback from a self-swab and clinician swab trial. Sex Transmitted Infections 2016;92:A61 

A recent study evaluating a new rapid sexual health testing, diagnosis and treatment service: Lorenc A, and others. What can be learnt from a qualitative evaluation of implementing a rapid sexual health testing, diagnosis and treatment service? BMJ Open 2021;11:e050109


Funding: This research was funded by the NIHR’s Research for Patient Benefit Programme.

Conflicts of Interest: The study authors declare no conflicts of interest. 

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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Study author

These findings have important implications for policymakers, funders, and providers of STI services throughout the world. Even in high-income countries, publicly funded health systems struggle to fund the cost of three diagnostic tests in men who have sex with men, let alone being able to introduce triple-site testing in females. This is despite undisputed evidence of its benefit in identifying additional infections.

During the COVID-19 pandemic, all sexual health services had to reduce face-to-face contact with patients and rely more on telephone or video consultations and postal kits for self-taken samples. Also, people who were shielding were not able to leave their homes and get to sexual health clinics. Being able to take their own swabs at home helped keep them safe. The SYSTEMATIC study gives reassurance that these self-taken samples are as accurate at finding gonorrhoea and chlamydia infections as samples taken by a clinician.

Financial pressures on the NHS have been made worse by the pandemic. Sexual health services are commissioned and funded by Local Authorities. Their public health budgets were cut in real terms between 2014/15 and 2019/20. This led to 25% cuts in sexual health service budgets over the period. However, rates of STIs have increased. Increased demand, with reduced budgets, has meant sexual health clinics have either had to restrict some services or adopt cost-saving methods of existing services. Using pooled samples would introduce significant cost-savings.

Janet Wilson, Consultant in Genitourinary Medicine and HIV, Leeds Teaching Hospitals NHS Trust 

British Association for Sexual Health and HIV 

The results of the SYSTEMATIC study make a strong case for self-taken, pooled samples for STI screening, particularly in women. UK sexual health services are under significant financial pressure and patient-focused initiatives like this, which also are cost-effective, are welcomed.

The known limitations of pooling include a small but significant effect on the detection of chlamydia. The authors recognised this. Even so, pooling was effective for screening men who have sex with men. And it was significantly better than genital-only screening in women (the current standard of care in many clinics).

Real-world questions remain, including whether patients would find pooled results acceptable. A previous UK survey identified concern amongst clinicians over managing pooled results, particularly in the absence of national guidance. Most clinicians were looking for further validation studies on pooling. This study adds to the growing international evidence base. It may in future lead to pooled sampling for STI screening becoming routine at sexual health clinics and via postal services.

Jonathan Shaw, Consultant Physician, Genitourinary & HIV Medicine, PHE Fellowship alumni assessing the potential role for pooled sampling in UK sexual health services, on behalf of British Association for Sexual Health and HIV (BASHH).

Sex therapist 

This paper offers policymakers and commissioners the opportunity to make an unhindered case for constructive change. 

The research shows where meaningful savings can be achieved without reducing service quality or efficacy. It offers more options to health professionals and provides for patients who prefer more control as well as those who need time and support. Putting this into practice would allow healthcare professionals to exercise more autonomy to provide within their local demographic.

Implementing this would require training for healthcare practitioners to outline new procedures and implications for budget and timing. Practitioner approval would be essential to success and so they should be given opportunities to raise any concerns and questions. For clinic users, information pamphlets could provide assurances of efficacy and benefits.

I occasionally refer clients to STI clinics. It is reassuring to feel confident that research and constructive change is ongoing.

Lorraine O’Connor, Relationship and Sex Therapist, Wokingham 

Member of the public

Self-testing appears to be a cost effective and accurate method of diagnosis. As long as the sample size is large enough to generalise the results, it should be recommended as a way to diagnose individuals who are comfortable with self-swabbing. 

Clinician-led testing should still remain an option because self-swabbing may not be appropriate for everyone. People who are homeless, for example, may be unable to ensure that samples are not contaminated.

Catherine Williams, Public Contributor, Abergavenny 

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