CDC guidelines for HIV prevention regimen may not go far enough, study suggests

January 9, 2017 by Enrique Rivero, University of California, Los Angeles
Robert Weiss. Credit: University of California, Los Angeles

A new study from the UCLA Fielding School of Public Health suggests modifying federal health guidelines related to the use of pre-exposure prophylaxis to prevent HIV transmission because current standards could miss some people who should be on it.

Pre-exposure prophylaxis, or PrEP, is a measure that has proven to be highly effective in preventing HIV transmission during unprotected sex. While not entirely foolproof, studies have shown taking daily doses of tenofovir disoproxil-emtricitabine, or Truvada, is 92 percent effective in preventing HIV infection when taken correctly and consistently.

Since 2012, the U.S. Centers for Disease Control and Prevention has recommended PrEP for gay or bisexual men who have had condomless anal sex or been diagnosed with a sexually transmitted infection in the past six months. The CDC also has recommended PrEP for HIV-negative men who have sex with men (MSM) and who are in a relationship with an HIV-positive partner.

The UCLA study, which was published in the January issue of Sexually Transmitted Diseases, suggests that those guidelines do not go far enough, because they omit important characteristics that could put someone at high risk for becoming infected with the virus that causes AIDS. Working with the Los Angeles LGBT Center, the researchers have developed an online risk assessment calculator, available today, which could fill that gap.

"To the best of our knowledge, this PrEP Calculator is the first of its kind to be based on real-world data," said Robert Weiss, co-author of the study and a professor of biostatistics at the Fielding School. "We hope that our PrEP calculator will allow more MSM to make a more-informed decision before deciding whether or not PrEP is right for them."

The Los Angeles LGBT Center is one of the largest HIV testing providers in Los Angeles County for gay, bisexual and MSM, with approximately 13,000 individual clients served annually, said lead author Matthew Beymer, a post-doctoral scholar in the department of medicine, division of infectious diseases, at the David Geffen School of Medicine at UCLA.

Between January 2009 and June 2014 the center collected data on various behavioral risk factors for HIV among clients at each visit. Center personnel used behavioral data and HIV test results to determine what characteristics distinguished MSM who were HIV-negative when the study began and subsequently tested positive for HIV during a follow-up visit from those who remained HIV-negative through the follow-up visits.

Using these data the researchers built an HIV-risk algorithm, which they use as a standardized mechanism for recommending PrEP to clients of the Los Angeles LGBT Center. Unlike the CDC guidelines, they asked important questions about a number of factors that could put one at higher risk for becoming infected, including substance use, number of sex partners, age and race or ethnicity, and other partner-level factors.

The researchers found that if all individuals who had a risk score greater than or equal to five on the test's scale—51 percent of those who used the calculator—had been given PrEP, then 75 percent of HIV infections would be averted during follow-up, assuming adequate regimen adherence and near complete effectiveness.

This made the researchers' model better than the CDC guidelines because it took into account behaviors that aren't considered in the current guidelines.

Based on these findings, they developed the risk calculator. The researchers will then assess whether men who have sex with men find it useful in determining if they should start taking PrEP. Even as late as September 2016, 20 percent of the Los Angeles LGBT Center's clients were unsure if PrEP was right for them, Beymer said.

"The findings from this study will allow MSM to determine their overall risk for HIV based on their own data and previous data collected at the Los Angeles LGBT Center," Beymer said. "Ultimately, this HIV score can be used by the client to determine if PrEP is right for them."

Beymer said that a limitation of this calculator is that it may not be appropriate for heterosexual and trans individuals, injection drug users, or people living outside of Los Angeles. In addition, it does not consider situations in which HIV-negative men are in long-term relationships with HIV-positive men.

Explore further: Most gay men not aware of treatment to protect them from HIV

More information: Matthew R. Beymer et al. Are Centers for Disease Control and Prevention Guidelines for Preexposure Prophylaxis Specific Enough? Formulation of a Personalized HIV Risk Score for Pre-Exposure Prophylaxis Initiation, Sexually Transmitted Diseases (2017). DOI: 10.1097/OLQ.0000000000000535

Related Stories

Most gay men not aware of treatment to protect them from HIV

October 5, 2016
Only four in 10 gay and bisexual men in Baltimore without HIV are aware that pre-exposure prophylaxis medication (PrEP) may significantly reduce their risk of contracting the virus, even those who had recently visited a doctor ...

Research suggests stigma could inhibit access to HIV prevention drug

December 8, 2016
The first study to explore United Kingdom men's perceptions of PrEP – a new HIV prevention treatment – has found that their opinions are negatively influenced by social stigma. The article published in Cogent Medicine ...

PrEP can reduce new HIV cases by a third among MSM over next 10 years

July 14, 2016
A daily pill to prevent HIV infection can reduce new cases among men who have sex with men (MSM) by a third in the U.S. over the next 10 years, according to a new modeling study published in The Journal of Infectious Diseases ...

Do men who have sex with men underestimate their HIV risk and miss out on preventive PrEP?

June 23, 2014
Men who have sex with men (MSM) have a disproportionately high risk of acquiring HIV, and unprotected sex between men accounts for most new HIV diagnoses in the U.S. Yet this population tends to underestimate their HIV risk ...

CDC urges anti-HIV pill for people at high risk of infection

May 15, 2014
(HealthDay)—People deemed to be at high risk for contracting HIV, the virus that causes AIDS, should take anti-HIV medicines that seem to cut transmission risk, the U.S. Centers for Disease Control and Prevention announced ...

Adapting the transtheoretical model of behavior change to understand PrEP engagement

December 13, 2016
One of the most groundbreaking HIV prevention strategies for HIV-negative gay and bisexual men (GBM) is a once-daily pill called pre-exposure prophylaxis (PrEP), which is up to 99% effective in the prevention of HIV infection. ...

Recommended for you

Researchers find latent HIV reservoirs inherently resistant to elimination by CD8+ T-cells

January 22, 2018
The latest "kick-and-kill" research to eliminate the HIV virus uncovered a potential obstacle in finding a cure. A recent study by researchers at the George Washington University (GW) found that latent HIV reservoirs show ...

HIV-1 genetic diversity is higher in vaginal tract than in blood during early infection

January 18, 2018
A first-of-its-kind study has found that the genetic diversity of human immunodeficiency virus type 1 (HIV-1) is higher in the vaginal tract than in the blood stream during early infection. This finding, published in PLOS ...

War in Ukraine has escalated HIV spread in the country: study

January 15, 2018
Conflict in Ukraine has increased the risk of HIV outbreaks throughout the country as displaced HIV-infected people move from war-affected regions to areas with higher risk of transmission, according to analysis by scientists.

Researchers offer new model for uncovering true HIV mortality rates in Zambia

January 12, 2018
A new study that seeks to better ascertain HIV mortality rates in Zambia could provide a model for improved national and regional surveillance approaches, and ultimately, more effective HIV treatment strategies.

New drug capsule may allow weekly HIV treatment

January 9, 2018
Researchers at MIT and Brigham and Women's Hospital have developed a capsule that can deliver a week's worth of HIV drugs in a single dose. This advance could make it much easier for patients to adhere to the strict schedule ...

New long-acting, less-toxic HIV drug suppresses virus in humanized mice

January 8, 2018
A team of Yale researchers tested a new chemical compound that suppresses HIV, protects immune cells, and remains effective for weeks with a single dose. In animal experiments, the compound proved to be a promising new candidate ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.