PrEP can cut new HIV infections by one-third in next decade

A new modeling study suggests that if pre-exposure prophylaxis were offered to 40% of eligible men who have sex with men, HIV incidence in the United States could be reduced by one-third during the next 10 years.

Researchers from Emory University, the CDC and the University of Washington used mathematical models of HIV transmission among MSM to estimate the percentage of HIV infections averted and the number needed to treat (NNT) to prevent one new infection after the implementation of the CDC’s PrEP guidelines. Issued in 2014, the guidelines call for uninfected MSM who are at “substantial risk” for HIV infection to receive Truvada (emtricitabine/tenofovir disoproxil fumarate, Gilead Sciences). In the study, the researchers accounted for varying levels of treatment coverage and adherence.

Under the best-case scenario in which 40% of eligible MSM received PrEP and 62% of these men adhered to the combination treatment, 1,162 infections per 100,000 person-years — or 33% of expected infections — could be averted in the next decade. However, this positive forecast depends on a significantly higher coverage rate than is currently estimated in the U.S., according to study researcher Samuel M. Jenness, PhD, MPH, an infectious disease epidemiologist at Emory University.

“There’s a big gap between the 5% of MSM using PrEP today and those who could potentially benefit from it,” he said in a press release. “There’s still a lot of work to be done to promote this intervention and scale it up more broadly, but our models suggest that the CDC guidelines provide a good framework for doing so.”

The researchers noted that treatment adherence was a key driver in the success of PrEP across the various levels of coverage included in their transmission models. Under the ideal scenario, the NNT to prevent one new infection would be 25 per year. While improving coverage and adherence jointly increased the percentage of HIV infections averted in their study, only adherence itself was associated with a lower NNT.

Jenness and colleagues said interventions generally require a tradeoff between public health impact and efficiency. For example, analyses of the iPrEx trial suggested that extending PrEP to anyone who has performed anal intercourse without a condom would prevent even more infections, but also would increase the NNT to almost 100. The CDC guidelines, however, strike “a good balance” between impact and efficiency based on these findings, they said.

In a related editorial, Jared M. Baeten, MD, PhD, vice chair and professor in the department of global health at the University of Washington, noted that the increasing incidence of HIV infection in some groups despite having access to treatment in high-income settings suggests the status quo is not enough to drastically reduce new HIV infections.

Jared M. Baeten

“Every provider, public health professional, patient, and advocate who has seen the devastation wrought by HIV in the last 3 decades wants to see far fewer men and women presenting for care with a new diagnosis of HIV infection,” he wrote. “PrEP can be a part of that outcome, especially if pragmatic approaches are sought that aim to achieve the coverage necessary to gain population impact at scale.” – by John Schoen

References:

Baeten JM. J Infect Dis. 2016;doi:10.1093/infdis/jiw224.

Buchbinder SP, et al. Lancet Infect Dis. 2014;doi: 10.1016/S1473-3099(14)70025-8.

Jenness SM, et al. J Infect Dis. 2016;doi:10.1093/infdis/jiw223.

USPHS. Preexposure prophylaxis for the prevention of HIV infection in the United States – 2014: A Clinical Practice Guideline. http://www.cdc.gov/hiv/pdf/PrEPguidelines2014.pdf. Updated May 14, 2014. Accessed July 13, 2016.

USPHS. Preexposure prophylaxis for the prevention of HIV infection in the United States – 2014: Clinical Providers’ Supplement. http://www.cdc.gov/hiv/pdf/PrEPProviderSupplement2014.pdf. Updated May 14, 2014. Accessed July 13, 2016.

Disclosures: The researchers report no relevant financial disclosures. Baeten reports leading studies of PrEP in which study medication was donated by Gilead Sciences.