Study results indicate that the incidence of HIV acquisition was very low among patients prescribed pre-exposure prophylaxis (PrEP) to prevent HIV infection at clinics in metropolitan areas heavily affected by HIV, despite a high incidence of sexually transmitted infections.
Study results indicate that the incidence of HIV acquisition was very low among patients prescribed pre-exposure prophylaxis (PrEP) to prevent HIV infection at clinics in metropolitan areas heavily affected by HIV, despite a high incidence of sexually transmitted infections (STIs). The study—published online on November 6, 2015 in JAMA Internal Medicine—also found that adherence to PrEP was highest among participants who reported more risk behaviors.
Previous randomized clinical trials have demonstrated the efficacy of PrEP in preventing HIV acquisition. However, little had been know until the current study regarding adherence to the regimen, sexual practices, and overall effectiveness when PrEP is implemented in clinics that treat STIs and community-based clinics serving men who have sex with men (MSM). These are promising sites for the delivery of PrEP, as MSM account for more than two-thirds of new HIV infections in the United States.
For the study, a demonstration project was conducted by Albert Y. Liu, MD, MPH, an internist with the San Francisco Department of Public Health, and colleagues from October 1, 2012 through February 10, 2015 (the last day of follow-up) among 557 MSM and transgender women in two municipal STI clinics in San Francisco and Miami and a community health center in Washington, DC. For 48 weeks, a combination of daily, oral tenofovir disoproxil fumarate and emtricitabine was provided. All participants received HIV testing, brief client-centered counseling, and clinical monitoring. Self-reported numbers of anal sex partners and episodes of condomless receptive anal sex as well as incidence of STI and HIV acquisition were recorded.
Among participants, 78.5% were retained through 48 weeks. Tenofovir diphosphate levels were measured in 294 participants, among whom 80.0% to 85.6% had protective levels (consistent with four or more doses per week) at follow-up visits. Those who were least likely to have protective levels were African American (56.8% of visits) or treated at the Miami site (65.1%). Those who were most likely to have protective levels had stable housing (86.8%) or reported at least two condomless anal sex partners in the past 3 months (88.6%). During follow-up, the average number of anal sex partners declined, from 10.9 to 9.3. However, the proportion of participants who engaged in condomless receptive anal sex remained stable at about two-thirds.
Overall STI incidence remained high throughout the study, at 90 per 100 person-years, whereas only two participants contracted HIV during follow-up, making for an incidence of 0.43 infections per 100 person years. The infection was detected about 19 weeks after study enrollment in one participant and about 4 weeks after the 48-week visit in the other patient, when PrEP was no longer being dispensed. Both individuals had tenofovir diphosphate levels that were consistent with less than two doses per week at seroconversion.
“Adherence was higher among those participants with more reported risk behaviors,” concluded the authors. “These results provide support for expanding PrEP implementation in MSM in similar clinical settings and highlight the urgent need to increase PrEP awareness and engagement and to develop effective adherence support for highly affected African-American and transgender populations.”