HIV study: 76% drop in cases with expanded treatment
by Matthew S. Bajko
New HIV infections among gay and bisexual men in San Francisco could fall 76 percent over the next five years due to the city's push to test people for the virus and advice that those infected begin taking antiretroviral therapy regardless of their CD4 T-cell count, say UCSF researchers.
The finding is the result of a study conducted by Edwin Charlebois, MPH Ph.D., an associate professor of medicine at UCSF, and colleagues to be published in the April 15 issue of Clinical Infectious Diseases .
"By expanding when we start antiretroviral therapy to people already in care we can have a significant impact on the HIV epidemic here in San Francisco," Charlebois told the Bay Area Reporter in a phone interview.
Last year the UCSF Division of HIV/AIDS at San Francisco General Hospital became the first clinical practice in the country to recommend treatment upon diagnosis to all of its HIV-infected patients. The San Francisco Department of Public Health also adopted the policy, which was not without controversy.
Some AIDS doctors, people living with HIV, and activists question the need for HIV-positive people to immediately begin taking the drugs. Federal guidelines recommend that HIV-positive people begin treatment when their CD4 T-cell count falls below 500.
Advocates of the treatment policy say it not only benefits HIV-positive patients, whose major organs would otherwise be under attack by the virus, but also has community benefits. As the B.A.R. reported last month, local epidemiologists point out that the policy helps to suppress people's viral loads, and that in turn, reduces their chances of transmitting HIV to sexual partners.
"Recent evidence has shown that ART reduces the probability to pass HIV infection on to another person. It is dramatically lowered if not eliminated," said Charlebois, who is also the co-director of methods core at the Center for AIDS Prevention Studies and co-director of prevention at the AIDS Policy Research Center/AIDS Research Institute.
Yet the researchers caution that there is still no evidence to confirm that the treatment policy has led to a reduction in HIV infections in San Francisco.
"Our clinicians recommended initiating antiretroviral therapy to all of our HIV-positive patients based on our assessment that delaying treatment allows the virus to do damage to major organs systems and would lead to poorer outcomes for patients. It is too early to tell if this shift in treatment strategy last year by our clinic and the Department of Public Health has had any impact in preventing HIV infections," stated study co-author, Dr. Diane V. Havlir, chief of the UCSF Division of HIV/AIDS at San Francisco General Hospital.
Havlir added that, "Notwithstanding the community benefit from reduced rates of new infections – which we view as an added gain – we strongly believe that the primary reason HIV patients should start antiretroviral therapy upon diagnosis is so that they will experience better health and will have a longer life span than if they had waited."
According to the latest estimates, San Francisco continues to have an HIV endemic, meaning that cases remain flat year after year. The number of new HIV infections have steadily declined over the last decade, dropping from a high of 1,000 per year to as low as 621 per year.
The UCSF researchers looked at three different models for HIV testing and treatment among men who sex with men in San Francisco. One tested the impact of following federal guidelines for treating HIV patients with CD4 T-cell counts below 500; a second looked at treatment for all HIV-positive people receiving care; and the third was a combined test and care policy.
They based their projections on local HIV surveillance information about HIV prevalence and incidence, testing rates, and treatment outcomes data from the health department and general hospital's outpatient HIV treatment clinics. The information covered 95 percent of known HIV-positive individuals in the city.
The researchers predicted that with just a treatment for people in care policy, new HIV infections among MSM would drop by 60 percent in five years. When combined with the push to test people so they know their status, the decrease in new infections would be 76 percent.
"Our findings show that we can obtain even greater reductions in new HIV infections if we do a better job of encouraging people to get tested, continue to improve our linkages to care and offer treatment to all HIV patients," stated Havlir.
Through the implementation of the "test and treat approach," the researchers also predict that the number of gay and bisexual men living with HIV in the city would be cut in half over the next 20 years, from about one in four to one in eight. The city estimates that there currently are 15,783 gay and bisexual men living with HIV in San Francisco.
"The model does not predict elimination of the HIV epidemic among MSM in San Francisco," states the study. "However, at 20 years, the test-and-treat strategy predicts reduction in prevalence of HIV infection among MSM in San Francisco from 26.2 percent to 12.8 percent."
In an editorial commentary accompanying the study, Victor DeGruttola, in the Department of Biostatistics at Harvard School of Public Health, and Dr. Robert T. Schooley, at the UC San Diego Department of Medicine's division of infectious diseases, write that due to the uncertainty that comes from modeling exercises, more research is needed into "test and treat" interventions before they become universally adopted.
The study, they caution, "cannot tell us what will and will not be cost-effective in different regions of the world." They also warn that modeling exercises "are not based on any genuine attempt to understand the true nature of sexual and transmission networks and, therefore, may not produce reliable results."
Charlebois and his colleagues point out in their study that the results they found are dependent on several components, ranging from patients remaining in care and having access to not just medical treatment but also housing, mental health, and substance use services.
"Also of concern is the potential for changes in behavior among MSM leading to increased transmission risk, thereby offsetting any potential gains and the specter of drug-resistant strains of HIV," they write, adding that, "these obstacles are not insurmountable" and note there has been little evidence to suggest greater risk behavior among MSM.
In addition, they emphasize that contrary to another modeling study that grabbed headlines, "transmitted drug resistant HIV strains have remained stable or even decreased in San Francisco and in similar cities."
The study is titled "The Effect of Expanded Antiretroviral Treatment Strategies on the HIV Epidemic among Men Who Have Sex with Men in San Francisco." Co-investigators for the study are Moupali Das from DPH and Travis Porco from UCSF.
The National Institute of Mental Health provided funding for the study through a grant to the UCSF Center for AIDS Prevention Studies.
It can be found at http://cid.oxfordjournals.org/content/52/8/1046.full?etoc.