HIV incidence rising in older gay men in Holland, most men recently infected undiagnosed

A study analysing HIV incidence in three cohorts of gay men in the Netherlands has found that increasing numbers of older gay men are being infected with HIV in Amsterdam. The study, published in the February 19^th edition of AIDS, also found that many gay men attending a sexual health clinic were refusing HIV tests. The investigators recommend that HIV prevention initiatives specifically for older gay men should be developed and that HIV tests should become routine for gay men in sexual health clinics.

There have been recent fears of a “second epidemic” of HIV amongst gay men. Some studies have apparently shown that gay men are becoming complacent about HIV because of the effectiveness of antiretroviral therapy, and there has been a significant increase in the rates of bacterial and viral sexually transmitted infections in many industrialised countries.

However, there are inconsistent data regarding HIV incidence amongst gay men. Studies from the United Kingdom, Sydney (Australia) and San Francisco (United States) appear to show stable incidence of HIV, whereas investigators in Italy and Canada have demonstrated rising trends in incidence. A study published in 2002, including data from 1991 and 2001, showed an increase in HIV incidence amongst gay men aged 35 and over in Amsterdam. During this period HIV incidence amongst younger gay men was stable.

Investigators now wished to describe HIV incidence in three cohorts of Dutch gay men: the Rotterdam Cohort Study (ROHOCO), the Amsterdam Cohort Study (ACS) and the Amsterdam STI Clinic. In particular, they wished to see if there continued to be a difference in HIV incidence between older and younger gay men. They also sought to determine the HIV testing behaviour of Dutch gay men.

The ACS included almost 1,500 gay men who were recruited between 1984 and 2005. All were HIV-negative on entry. The ROHOCO recruited 286 men between 1999 and 2000, and once again all the men were HIV-negative at baseline. Anonymous HIV surveillance data were available for just over 4,400 gay men attending the Amsterdam STI clinic between 1991 and 2004.

There was a significant increase in the odds ratio of HIV incidence at the Amsterdam STI clinic in the period 1999-2004 (3.75) compared to 1991-1998 (1.81). An increase in HIV incidence in the ACS was also observed in the 1999-2005 period (1.24) compared to the earlier time period (1.13). Incidence in the ACS and Rotterdam cohorts were not comparable.

Further analysis revealed that, although there was a statistically significant increase in HIV incidence amongst gay men in the ACS (p = 0.003), there was also a statistically significant difference between younger and older gay men (p = 0.0135) and that the significant increase in older gay men observed in 2002 was still apparent in data to the end of 2005. Once again, no significant increase in HIV incidence amongst younger gay men in the ACS was detected.

In the Rotterdam cohort, the investigators noted that HIV incidence also increased amongst older gay men, but remained stable in those under 35, but the difference was not statistically significant.

Between 1999 and 2005, HIV incidence was lowest amongst gay men under 30 attending the Amsterdam STI clinic. HIV incidence was highest amongst men with a concurrent sexually transmitted infection (STI clinic, odds ratio: 7.57; ACS, 2.51; ROHOCO, 11.71).

Gay men attending the Amsterdam STI clinic were tested anonymously for HIV. Before 2002 only 21% of men with recent HIV infection who had an anonymous HIV test also accepted a named HIV test. In 2002, the clinic started to actively promote HIV testing. Nevertheless, only 40% of men with recent HIV infection accepted a named HIV test.

“The present study has demonstrated a continuing HIV epidemic in MSM in The Netherlands, being between one and four infections per 100 person years in the period 1999 and 2005”, write the investigators, adding, “we confirm an increase in incidence among older MSM”.

The investigators also express concern about the “high rate of unawareness of HIV infection among MSM.” They conclude that HIV prevention initiatives should be developed with older gay men in mind, and that HIV tests should become part of routine sexual health screens for gay men.