More than 40% of Gay Men with HIV in the U.K. Are Undiagnosed, and 60% of Them Believe They Are HIV Negative

Men who have sex with men (MSM) continue to be the group most at risk of acquiring HIV in the U.K., and increases in incidence of HIV and other sexually transmitted infections (STIs) remain a matter of concern, according to the authors of a study in the May 31, 2008 issue of AIDS.

Current estimates suggest that 28,000 MSM in the U.K. were living with HIV in 2005. While HIV antibody testing has increased markedly, an estimated 32% remained unaware of their HIV positive status.

Undiagnosed infection presents a significant risk for the onward transmission of HIV. In the U.S. it is estimated that at least half of new sexually transmitted HIV infections originate with people who are unaware of their HIV status. U.S. studies have shown that gay men with undiagnosed infection often delay HIV testing, are afraid of receiving a positive result, and perceive themselves to be at low risk despite reporting HIV-related sexual risk behaviors and presence of other STIs.

It is estimated that testing at-risk MSM biannually could contribute to a two-thirds reduction in HIV exposure, but this relies in part on an assumption of lower sexual risk among those who become aware of their HIV positive status.

In U.K. community-based surveys, HIV positive men generally report higher levels of sexual risk behavior than HIV negative men and those who have never been tested. However, the differences between men who are and are not aware of their HIV status, and the role of undiagnosed HIV in the U.K. epidemic, have not been explored.

In the current study, researchers explored the extent of undiagnosed HIV infection among MSM in 5 U.K. cities (London, Brighton, Manchester, Glasgow, and Edinburgh) and examined the similarities and differences between men with undiagnosed HIV, men aware of their HIV positive status, and HIV negative men.

Results

• Of 3501 men with a confirmed positive or negative oral fluid result, 318 were HIV positive (9.1%).

• Of these, 131 (41.2%) were previously undiagnosed.

• 81.1% of men with undiagnosed HIV had previously been tested (92.2% tested negative; the remainder did not know the result).

• 62.3% still thought that they were HIV negative.

• Both undiagnosed and diagnosed HIV positive men reported greater sexual risk and sexually transmitted infections than HIV negative men.

• Compared with HIV negative men, the adjusted odds ratio of unprotected anal intercourse with 2 or more partners was higher among undiagnosed men, but highest among diagnosed men.

Based on these results, the study authors concluded, "A high proportion of the HIV-positive men were undiagnosed and not receiving benefits of clinical care, but sexual risk and sexually transmitted infections were highest among men who were aware of their HIV-positive status."

Further, they recommended, "Clinics should proactively offer testing to reduce undiagnosed HIV, target repeat testing at high-risk men who have previously tested negative, and initiate evidence-based behavioral interventions to reduce sexual risk among men living with diagnosed HIV as well as those testing negative."

MRC Social and Public Health Sciences Unit, Glasgow, UK; Centre for Sexual Health and HIV Research, Department of Primary Care and Population Sciences, Royal Free and University College Medical School, University College London, London, UK.

6/17/08

Reference
LM Williamson, M Lisa, JP Dodds, and others. Reference Sexual risk behavior and knowledge of HIV status among community samples of gay men in the UK. AIDS 22(9): 1063-1070, May 31, 2008.