A multifaceted approach may be needed to reduce HIV risk in MSM

March 2008

BOSTON – To lower HIV transmission rates among men who have sex with men, significant changes in prevention strategies may be necessary, according to Ronald Stall, MD, professor in the department of behavioral and community health sciences at the University of Pittsburgh.

At the 15th Conference on Retroviruses and Opportunistic Infections, held recently in Boston, Stall said a “prevention cocktail” may be needed to better fight HIV transmission among MSM in the United States. Stall suggested HIV prevention efforts should be expanded to address the epidemic from various angles. “A prevention cocktail would include interventions at both the individual patient level and the public health level,” Stall said.

As part of the prevention cocktail, Stall called for increased epidemiological research to characterize new HIV risks, efforts to lower community viral load, medical care and prevention services for undiagnosed patients with HIV and those who have been diagnosed but who are not receiving treatment, access to health care for all at-risk populations, access to treatment for comorbid conditions and a supportive policy environment to promote health agendas for MSM.

Stall agreed that some people may think such an approach is unfeasible; but he believes improvements in prevention strategies could have significant benefits for public health.

Current prevention efforts

Stall questioned the efficacy of current prevention efforts aimed at MSM in the United States. He cited a study by Herbst et al that appeared in the Journal of Acquired Immune Deficiency Syndromes in 2005; this study’s results showed a reduction in risk behaviors among MSM who were exposed to prevention campaigns.

“The Herbst group also reviewed and identified characteristics of those interventions that were associated with the most significant reductions in high-risk behaviors,” Stall said. “The HIV behavioral interventions that worked best were therapy-based, included group discussion, had multiple message delivery methods and had greater intervention exposure. So, as this research indicated, HIV interventions can work if they are well-funded and well-fielded.”

To determine how well HIV prevention campaigns are working among American MSM, Stall and his colleagues conducted two independent literature reviews examining the incidence rates of HIV among American MSM between 1995 and 2005. These rates were compared with the incidence rates in MSM for other industrialized nations.

The results showed that HIV incidence rates differed by continent. The rate was lowest in Australia, at 1.1%. In Europe, it was 2.4%; in North America, it was 2.8%. The results also demonstrated that the incidence rates did not change significantly between 1995 and 2005.

Model cohort study

Stall and his colleagues conducted a model cohort study to examine the potential lifetime risk of HIV infection among MSM in the United States. Using the current estimated HIV incidence rate of 2.39% for this patient population, the researchers created a model cohort of young MSM at age 18 with no HIV infection at baseline and tracked their lifetime risk of contracting HIV.

By age 20, less than 5% of the model cohort would have contracted HIV. At age 25, this rate increased to 15%; by age 30, it was 25%; by age 40, the rate was 41%.

Among black MSM in the United States, the rates were even higher. Using the lowest rates of HIV incidence reported for black MSM in the United States, 4%, the model showed that by age 25, 25% of black MSM will be HIV positive. By age 35, the rate was 50%; by age 40, it was 60%.

“Needless to say, we were horrified by these prevalence assessments and wondered if there was something wrong with what we had done,” Stall said. “So we looked at prevention rates from the CDC; but these figures corroborated our findings.”

Stall said this cohort study is proof that more must be done to help reduce the risk of HIV transmission among MSM. “This does not predict something that may happen one day,” Stall said. “What we are showing is the epidemiological phenomenon that is occurring now among MSM aged 40 and younger and will continue to occur if we do not find ways to lower HIV incidence rates even further.”

Syndemic

Stall said there is a set of social, psychological and health factors that are affecting the HIV epidemic among MSM in the United States today.

“It may be a fallacy to say that HIV is the dominant, most dangerous and most damaging epidemic among gay men in the United States today,” Stall said. “There are at least four other epidemics occurring among gay men that are intertwining and making each other worse. This is called a syndemic.”

Stall cited the population-based Urban Men’s Health Study, which demonstrated that at least four other epidemics – substance abuse, partner violence, depression and childhood sexual abuse – may be affecting this patient population.

“What do these other factors have to do with HIV infection?” Stall said. “The analysis further demonstrated that men who were most affected by this syndemic were also more likely to have recently engaged in high-risk sex and/or be HIV positive. Therefore, we now have these co-occurring psychosocial conditions that are intertwined and are making each other worse driving an infectious disease epidemic.”

Stall added that other marginalized populations – including ethnic minorities and the urban poor – may also be suffering from a similar syndemic; this may be further exacerbating the HIV/AIDS epidemic in these patient populations as well.

Addressing health concerns

Stall said health care providers may be treating MSM who have many questions about their health risks. “MSM are facing many prevention questions,” Stall said. “What specifically is risk? How safe do I want to be? How do I maintain safe sex for decades on end? What can I do about my coexisting conditions that may influence my HIV risk? What can I do about community viral load? How do I maintain safety when I am under constant homophobic attacks?”

To properly care for these patients and to adequately address their health questions, Stall suggested prevention efforts may need to be expanded.

He said multiple levels of prevention — including individual, interpersonal, community, public health and government policy – could be used.

“What could HIV prevention look like if it incorporated multiple mechanisms of treatment efficacy?” Stall asked.

Stall said he thinks it is essential that current prevention efforts be reexamined and may need to be redesigned to better reduce HIV risk among MSM. “If nothing changes, ongoing incidence rates at the current level will yield very high HIV prevalence rates in each new generation of gay men,” he said. “We have strong evidence to show that more ambitious HIV prevention programs are more efficacious. Furthermore, few intervention programs are currently addressing all the issues that MSM are facing.”

Stall said intervention strategies that test multiple mechanisms of prevention efficacy must be attempted. Stall acknowledged that this agenda may seem ambitious and many may doubt that it would be realistic to implement.

But Stall again cited the HIV/AIDS epidemic in Australia. In Australia, prevention programs are more prevalent and more multifaceted than in the United States, and the risk of transmission among MSM is less than half that of the risk among American MSM.

“So clearly, we can yield better effects for prevention efforts in the United States,” Stall said. “And clearly, the stakes in the fight against HIV/AIDS are so profound; we have to take up this challenge.”

For more information:

• Stall R. What’s driving the U.S. epidemic in men who have sex with men? #53. Presented at: The 15th Conference on Retroviruses and Opportunistic Infections; Feb. 3-6, 2008; Boston.