A new meta-analysis, presented to the 19th International AIDS Conference (AIDS 2012) on Tuesday, shows that the exceptionally high rates of HIV infection seen in black men who have sex with men (MSM) cannot be explained by the factors very often thought to drive HIV epidemics – frequency of having sex without a condom, number of sexual partners, drug use and so forth.
In comparison with MSM of other ethnic groups, black men have either comparable rates of risky behaviour, or less. But they are much more likely to report socioeconomic problems and barriers to accessing care, suggesting that the explanation may lie at the structural rather than individual level.
Greg Millett of the Centers of Disease Prevention Control presented the data at a session organised by the medical journal The Lancet, which has just published a special issue on HIV in men who have sex with men, distributed to every conference delegate.
In the United States, HIV is concentrated in men who have sex with men (around 2% of the population but 61% of new infections) and in black people (14% of the population but 44% of new infections).
And there is a particular concentration in men who belong to both categories – compared to the general black population, black MSM have 22 times the odds of being HIV positive. Furthermore, the conference heard on Monday that in one cohort of black MSM, 3% of men acquire HIV every year.
In order to better understand the problem, Millett and colleagues conducted a meta-analysis that identified and pulled together all the relevant studies that had already been conducted. They were specifically interested in research that made comparisons between black MSM and MSM of other ethnic groups, and which examined factors that might be associated with HIV infection.
A total of 174 studies that met predetermined criteria were identified, either from peer-reviewed journals or from conference proceedings. Their data were pooled in order to produce more reliable estimates that would not be so dependent on the particularities of the samples recruited for the individual studies.
In total, 69 different factors were examined. In the paragraphs that follow, the figures in the brackets are odds ratios – when an odds ratio is above 1, it means black men have an increased likelihood of reporting the factor. When it is below 1, black men are less likely to report the factor than men of other racial groups. All figures reported are statistically significant.
Firstly the analysis confirmed that black men who have sex with men in the United States are at increased risk of HIV infection. Black men had a three-fold greater odds of testing HIV positive (3.0) and a six-fold greater odds of having undiagnosed HIV infection (6.38) compared with other MSM.
But it is notable that black MSM reported fewer sexual risk behaviours than MSM of other ethnic groups. They were less likely to report unprotected anal intercourse (though this was not statistically significant), they were less likely to have a high number of sexual partners (0.58) and they were more likely to use condoms (2.06). They were more likely to have tested for HIV in the past year (1.51).
There were no differences between the ethnic groups in terms of having multiple partners at the same point in time, being HIV negative and knowingly having sex with an HIV-positive man, or having unprotected sex with a man of a different HIV status. Black HIV-negative men were less likely to report unprotected sex with men they thought were HIV negative (0.51).
Perceived risk of HIV infection, HIV treatment optimism beliefs and circumcision status did not differ between black MSM and other MSM. They were, however, more likely to report selling sex (1.54).
Black MSM were less likely to engage in any substance use (0.67), including of crystal methamphetamine (0.39) although there was a non-significant trend to greater use of crack cocaine.
Although black men were as likely as other men to have sexual partners from the same ethnic group, they were more likely to have black partners (11.47).
However, pronounced disparities were seen between black MSM and other MSM in relation to experiencing socioeconomic difficulties and structural barriers (2.28). Specifically, black men were more likely to have finished education before the end of high school (3.50), to earn less than $20,000 a year (2.29), to have been incarcerated (2.17) or to be unemployed (1.5).
The authors suggest that these interrelated factors will affect the availability and choice of sexual partners and may be associated with isolation in a person’s own neighbourhood, in which HIV is likely to be highly prevalent.
The researchers are looked specifically at the 33 studies that compared young black MSM with young MSM of other ethnic groups. ‘Young’ here could be anywhere between 13 and 29 years.
Young black MSM were as likely as other young MSM to have ever had unprotected anal sex, but were less likely to have done so in the past six months (0.73). They had a similar number of sexual partners to their peers of other racial groups and had similar rates of HIV testing. They were particularly unlikely to report any substance use (0.22).
Despite this, young black men were five times more likely to have HIV (4.95), seven times more likely to have undiagnosed HIV (7.14), and had a greater chance of being diagnosed with an STI than other young MSM (1.45).
Notably, young black MSM were more likely than others to begin having sex at a younger age (1.65), which is associated with having a greater number of sexual partners and HIV infection. They were also more likely to have older sexual partners (1.52), which increases the chances of having an HIV-positive partner.
Moreover, more young black men reported a history of childhood sexual abuse (1.82). They were also more likely to have a low income (3.05).
Black MSM and the HIV treatment cascade
A key concept for anyone considering the success of anti-HIV treatment in improving the health of individuals and in preventing onward transmission in their communities is the ‘treatment cascade’ or ‘care continuum’. This shows how, at every stage, patients are not retained in the healthcare system or are unable to access the medical care they need. (The graphic relates to all Americans with HIV, not black MSM specifically.)
Millett’s meta-analysis identified a number of risk factors for HIV-positive black MSM in relation to the care continuum. As noted above, black men had a far greater likelihood of having undiagnosed HIV (6.38).
Furthermore, the following odds ratios are derived from the 24 studies that compared black MSM living with HIV with their peers of other racial groups. Black men were less likely to:
- Have health insurance (0.47).
- Attend clinic visits (0.61).
- Start treatment before CD4 cell count fell below 200 copies/ml (0.40).
- Take antiretroviral therapy (0.56).
- Be adherent to antiretroviral therapy (0.50).
- Have an undetectable viral load (0.51).
Commenting on these findings, Chris Beyrer of Johns Hopkins University said that structural change was essential, but that the data set out a map for what needs to be done. “We have to address each one of those steps with interventions that make sense for men, that are led by the community, that protect human rights and that are grounded in biological insights,” he said.
Greg Millett, the lead researcher on this meta-analysis, began as a community activist and became an epidemiologist who has purposefully and persistently drawn attention to racial disparities in HIV infection.
In 2009 he was seconded to the White House to work on the country’s first ever National HIV/AIDS Strategy.
It is notable that inequalities are a key focus of the strategy – reducing HIV-related health disparities and increasing access to healthcare are two of the three primary goals. And in order to achieve the other primary goal, reducing new HIV infections, the first step is to intensify HIV prevention efforts in the communities where HIV is most heavily concentrated.
It remains to be seen whether the strategy will affect real change in prevention work and health outcomes, but many government officials and advocates argue that President Obama’s healthcare reform law will make a substantial difference by providing health coverage to the 49 million Americans who currently lack health insurance and are not covered by Medicaid (which provides some healthcare to some people with a low income). Black people and young adults on lower incomes are especially likely to be uninsured.
Some important questions remain unresolved – including whether insurers will be obliged to cover the costs of HIV testing – but a key aspect of the Affordable Care Act is that insurance companies won’t be able to refuse to cover people because they have HIV.
In a plenary speech, Phill Wilson of the Black AIDS Institute described the law as the “most important piece of domestic legislation in the last 40 years.”
“Because of this law, no insurance company can deny insurance because of pre-existing conditions, jack up your rates, or drop you because you get sick or because your care costs too much,” he said. “For people with AIDS, these provisions are absolutely life-saving.”
Millett G et al. Comparisons of disparities and risks of HIV infection in black and other men who have sex with men in Canada, UK, and USA: a meta-analysis. The Lancet doi:10.1016/S0140-6736(12)60899-X, 2012.
Download the resource from The Lancet's website. (Full text available after free registration.)