The study found that the likelihood of being newly diagnosed with hepatitis C was not significantly greater in gay men than it was in heterosexual men, and hepatitis C infection was much more strongly associated with having HIV than it was with sexual orientation.

Dr Jo Turner told the conference that the University College Hospital (UCH) Centre for Sexual Health, wishing to establish if the apparent rise in hepatitis C infections in positive gay men was matched by a similar rise in HIV negative men, had decided to offer hepatitis C tests to all men attending the GUM clinic for STI checkups between March 2007 and March 2008.

Over the year 10,204 men attended the GUM clinic and 4,554 (44%) accepted the offer of a hepatitis C test. Dr Turner was reporting on 4,472 valid results. The men who accepted the offer of a hepatitis C test were more likely to be gay (58% of those accepting a test, 48% of those turning one down), less likely to be African or Caribbean (8.7% of those accepting, 13.3% of those not accepting) and more likely to be injecting drug users (2.4% of those accepting, 1.0% of those refusing).

The average age of all the men was 34. Seventy-one per cent were of white ethnicity, about 8% black, 6% Asian and the rest other/mixed. Nearly a quarter (1032 or 23%) were HIV positive, 3122 HIV negative at their last test, and 318 did not know their HIV status at the time they were tested for hepatitis C. One hundred and eight (2.5%) were or had been injecting drug users and another 77 (1.7%) were both gay and injecting drug users. Acute STIs were diagnosed in 775 men (17.3%).

Hepatitis C testing was conducted by antibody-testing pools of twelve blood samples. If the pool tested positive, sub-pools of four were tested and these tested individually if the sub-pool tested positive. Individual samples that tested HCV antibody positive were also tested for hepatitis C RNA (viral load).

So far one hundred and fourteen hepatitis C infections (2.55%) have been confirmed in the group. Of these 97 were already known and 17 were newly diagnosed infections.

The hepatitis C rate in HIV positive men was 9.3% (82 infections), and was no different in gay men (9.25%) than in all men. Similarly the rate in HIV negative men, 0.51% (16 infections), was no different in HIV negative gay men (0.49%). There was one infection in a heterosexual man of unknown HIV status.

The 17 newly diagnosed infections comprised ten infections that appeared to be chronic, three where people tested antibody positive but had cleared the HCV virus, and four that appeared to be incident (recent). Of the ten new diagnoses of chronic infections, six were in HIV positive men, three of whom were injecting drug users. Two were in HIV negative gay men, one in an HIV negative drug user, and one in a man without any hepatitis C or HIV risk factors.

Three of the four incident infections were in HIV positive men. The one in an HIV negative man was interesting; he was a gay man with an HIV positive partner and his sexual risk behaviour commented Dr Turner, suggested that he was at high risk of both HIV and hepatitis C. However he had told the staff he was taking anti-HIV drugs as pre-exposure prophylaxis to prevent infection by his partner. Dr Turner told the conference that, independently of the study, liver function testing had revealed another five incident hepatitis C infections in untested male clinic attendees during the same period.

If injecting drug users were excluded, the hepatitis C rate was 2.9% in gay men and 0.4% in heterosexuals, but the difference was solely due to the fact that more of the gay men had HIV. The hepatitis C rate was 7.5% and 6.5% respectively in HIV positive gay and heterosexual men, and 0.4% and 0.2% in HIV negative gay and heterosexual men; neither of these differences was statistically significant.

Dr Turner concluded that there was no evidence of an increased risk of hepatitis C infection in HIV negative gay men.

Asked to comment on the source of hepatitis C infections in HIV positive men, given that rates in non-drug using men were the same regardless of sexual orientation, Dr Turner said analysis of behavioural risks were ongoing but speculated that infections might be due to non-sexual exposures such as undisclosed needle use.

Reference
Turner J et al. Is there an unrecognised epidemic of hepatitis C infection in men who have sex with men? Fourteenth British HIV Association Conference, Belfast. Abstract O22. 2008.