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Bristol study reveals changing sexual behaviours and increase in clinic attendance and sexually transmitted infections 

7 September 2021 

A study looking at the impact of PrEP among men who have sex with men and transgender people who have sex with men, has found sexually transmitted infection (STI) diagnoses have increased along with the likelihood of having condomless anal intercourse. 

Condom in packaging

Pre-exposure prophylaxis for HIV (PrEP) is a medicine for people who don’t have HIV which can reduce the risk of catching it. In the UK, men who have sex with men and transgender people who have sex with men are more exposed to HIV. 

Previous research has shown PrEP is safe and effective in reducing the risk of HIV infection. The increased use of PrEP is likely to have played a part in the dramatic decline in new HIV diagnoses in the UK among men who have sex with men. PrEP may lead people to have more unprotected sex, which can lead to an increase in other STIs. People taking PrEP should have regular health checks, including tests for sexual infections. They are encouraged to attend sexual health checks every three months. 

Researchers from the NIHR Health Protection Research Unit in Behavioural Science and Evaluation at University of Bristol and NIHR ARC West examined trends in bacterial STIs in Bristol among men who have sex with men and transgender people who have sex with men. The team analysed 617 responses to an online patient questionnaire, alongside electronic patient records. These records covered 40,321 clinic attendees between 2016-2019, 3,977 of whom were men who have sex with men and transgender people who have sex with men.

The frequency in which both groups tested for HIV and STIs increased between 2016-2019. In 2016, each patient had an average of 1.5 STI tests a year, while in 2019 this was 2.1. The likelihood of an STI being diagnosed per test also increased across all populations, including among individuals who were recorded to have only partners of the opposite sex. The increase in diagnoses was most significant in bisexual men, which could lead to a rise in STIs in cisgender women.

The reasons for rising STI diagnosis rates are complex and not only the result of increased testing. The proportion of men who have sex with men and transgender people who have sex with men reporting unprotected anal sex rose from 40.6 per cent to 45.5 per cent. The average number of partners reported increased from 3.8 to 4.5. 

HIV-positive questionnaire respondents indicated they would be more likely to have unprotected anal sex with someone if their partner was taking PrEP, while 61.9 per cent of HIV-negative respondents said that if they were taking PrEP, it would make them more likely to have unprotected anal sex with HIV-negative partners.

Louis Macgregor, Senior Research Associate at the University of Bristol and the paper’s lead author, said: “It’s important to note that an increase in unprotected anal sex is not an unexpected or even necessarily negative consequence of PrEP. Those taking it are likely to consider and re-evaluate their own HIV risk management strategies against competing interests such as maximising sexual pleasure and feeling connected to their partners.

“The challenge is how we approach balancing HIV risk and sexual pleasure with the competing risks of STIs and antimicrobial resistance. The full interplay of increased testing, increasing PrEP use and behavioural changes is difficult to determine.”

Lindsey Harryman, Consultant in Sexual Health at Unity Sexual Health and co-author said: “The increase in the amount of STI testing suggests that health-promotion messages regarding regular testing when at increased STI risk are working. To tackle the issue of rising STI rates as PrEP is more widely used, we must take a holistic approach which addresses many factors. This includes helping men who have sex with men and transgender people who have sex with men to make informed decisions about the risks of condomless anal sex beyond HIV prevention strategies. 

“We now face the challenge and privilege of addressing sexual health messaging in an era of reduced HIV anxiety and fear.”

Paper: Evidence of changing sexual behaviours and clinical attendance patterns, alongside increasing diagnoses of sexually transmitted infections in MSM and trans persons who have sex with men by Louis Macgregor, Nathan Speare, Jane Nicholls, Lindsey Harryman, Jeremy Horwood, Joanna Kesten, Ava Lorenc, Paddy Horner, Natalie L. Edelman, Peter Muir, Paul North, Mark Gompels, Katy Turner. Published in Sexually Transmitted Infections


Further information

About the NIHR Health Protection Research Unit [HPRU] in Behavioural Science and Evaluation at the University of Bristol 

The NIHR HPRU in Behavioural Science and Evaluation at University of Bristol is one of 14 HPRUs across England, part of a £58.7 million investment by the NIHR to protect the health of the nation. 

The NIHR HPRU in Behavioural Science and Evaluation is a partnership between Public Health England and University of Bristol, in collaboration with MRC Biostatistics Research Unit at the University of Cambridge and University of the West of England. 

Each NIHR HPRU undertakes high quality research that is used by PHE to keep the public safe from current and emerging public health threats.

About the NIHR 

The mission of the National Institute for Health Research (NIHR) is to improve the health and wealth of the nation through research. We do this by:

  • Funding high quality, timely research that benefits the NHS, public health and social care;
  • Investing in world-class expertise, facilities and a skilled delivery workforce to translate discoveries into improved treatments and services;
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  • Attracting, training and supporting the best researchers to tackle complex health and social care challenges;
  • Collaborating with other public funders, charities and industry to help shape a cohesive and globally competitive research system;
  • Funding applied global health research and training to meet the needs of the poorest people in low and middle income countries.

NIHR is funded by the Department of Health and Social Care. Its work in low and middle income countries is principally funded through UK Aid from the UK government.