Many people with HIV not disclosing at GUM clinics: estimates of undiagnosed infections may be too high

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Many people with HIV are not disclosing their status when using sexual health clinics, according to the results of a study conducted at a large London genitourinary medicine (GUM) clinic and published in Sexually Transmitted Infections. This could mean that current estimates of the prevalence of undiagnosed HIV infections in the UK are too high. Moreover, because of non-disclosure, people with HIV may not be receiving appropriate care when using sexual health services.

It is estimated that approximately one-quarter of all HIV infections in the UK are undiagnosed. This estimate is derived from statistical modelling based on several surveillance- and survey-based sources. One of the surveillance programmes is the anonymous HIV testing of blood samples obtained from people attending GUM and sexual health clinics. This involves testing small samples of blood left over from routine syphilis screening for the presence of HIV antibodies. According to data collected in 2009, an estimated 27% of previously undiagnosed patients left the clinic unaware of their HIV infection.

However, there have been anecdotal reports that some people with HIV do not disclose their status when attending GUM clinics. If this was widespread, it could mean that the prevalence of undiagnosed infections may have been overestimated.



In HIV, refers to the act of telling another person that you have HIV. Many people find this term stigmatising as it suggests information which is normally kept secret. The terms ‘telling’ or ‘sharing’ are more neutral.

mathematical models

A range of complex mathematical techniques which aim to simulate a sequence of likely future events, in order to estimate the impact of a health intervention or the spread of an infection.

exclusion criteria

Defines who cannot take part in a research study. Eligibility criteria may include disease type and stage, other medical conditions, previous treatment history, age, and gender. For example, many trials exclude women who are pregnant, to avoid any possible danger to a baby, or people who are taking a drug that might interact with the treatment being studied.

lymphogranuloma venereum (LGV)

A sexually transmitted infection that can have serious consequences if left untreated. Symptoms include genital or rectal ulcers.


A sexually transmitted infection caused by the bacterium Treponema pallidum. Transmission can occur by direct contact with a syphilis sore during vaginal, anal, or oral sex. Sores may be found around the penis, vagina, or anus, or in the rectum, on the lips, or in the mouth, but syphilis is often asymptomatic. It can spread from an infected mother to her unborn baby.

Investigators at the John Hunter Clinic in London wanted to establish a clearer understanding of the proportion of their patients whose HIV was truly undiagnosed.

They therefore identified blood samples obtained from people with apparently undiagnosed HIV infection. Viral load monitoring and testing for the presence of anti-HIV drugs allowed the investigators to see if patients were actually aware of their infection.

A total of 130 HIV-positive samples were identified. Of these, 28 were from people not previously known to be HIV positive. However, ten of these patients were excluded because survey data showed they underwent an HIV test when attending the clinic. This left 18 people with apparently undiagnosed HIV infection.

Some 13 individuals (72%) had an undetectable (n = 11) or very low (n = 2) viral load. It is extremely rare for someone to have such a low viral load unless they are taking HIV treatment.

A total of eight samples were viable for testing for the presence of antiretroviral drugs. Results showed that all were positive. In each case, drug levels were at therapeutic levels.

“This is the first published objective evidence that non-disclosure of HIV status is a phenomenon is patients attending GU clinics in the UK,” comment the investigators, who believe the extent of non-disclosure should be examined in other clinics elsewhere in the UK.

They conclude, “non disclosure affects the estimate of the prevalence of HIV infection in attendees upon leaving the clinic.” It can also have implications for the health of individual patients. Some sexually transmitted infections require more intensive treatment in people with HIV, especially if they are not taking antiretroviral therapy. Rates of certain infections – including sexually transmitted hepatitis C and LGV – are much higher in people with HIV than other groups, and testing for these infections may be more likely to occur if staff are aware that someone is HIV positive.

A previous study, presented to the British HIV Association conference in 2011, came to similar conclusions. You can read our news report on that study here:


Sullivan AK et al. Non-disclosure of HIV status in UK sexual health clinics – a pilot study to identify non-disclosure within a national unlinked anonymous seroprevalence survey. Sex Transm Infect, online edition. DOI: 10.1136/sextrans-2012-050801, 2013.