Offering PrEP at public health-care clinics in a middle-income setting can retain high numbers of participants and achieve high levels of adherence without risk compensation in investigated populations.
Beatriz Grinsztejn, MD, PhD
In Brazil, men who have sex with men (MSM) account for approximately 3.5% of the population, but about 60% of reported human immunodeficiency virus (HIV) infections can be assigned to male-to-male sexual contact.
Though data is sparser for transgender women, most estimates suggest that a disproportionately large number (more than 30% according to 1 study) are also living with HIV. Researchers believe that aggressive interventions to prevent HIV infection among these 2 high-risk groups could significantly reduce the impact of HIV in Brazil.
The Brazilian Ministry of Health, in collaboration with several other agencies, funded a study to evaluate the impact of pre-exposure prophylaxis (PrEP) for HIV prevention among MSM and transgender women. The study, titled PrEP Brasil, was led by Beatriz Grinsztejn, MD, PhD, the Principal Investigator of the National Institutes of Health (NIH) Clinical Trials Unit at Instituto de Pesquisa Clinica Evandro Chagas-Fiocruz.
PrEP Brasil was an open-label, demonstration study that assessed PrEP with emtricitabine/tenofovir (Truvada) for HIV prevention among MSM and transgender women in Rio de Janeiro and Sao Paulo, Brazil from April 2014 to July 2016.
Patients included in the study were adults who were HIV-negative and met at least 1 sexual risk criterion, including condomless anal sex with 2 or more partners, 2 or more episodes of anal sex with an HIV-infected partner, or history of STI diagnosis, according to the study authors.
Extensive sociodemographic and behavioral characteristics were gathered for all study participants. Dried blood spots were collected at predetermined points during the study (weeks 4 and 48, at a minimum) to test for medication adherence.
At week 48, 375 patients were retained of the 450 patients who began the study. Retention in the study was not associated with any particular sociodemographic or behavioral characteristic. Overall, 277 patients of the 375 had concentrations of medication consistent with taking a minimum of 4 doses per week, which was defined as protective at the onset of the study.
The strongest predictor of having a protective concentration of the drug at week 48 was having a protective concentration at week 4. In addition, Grinsztejn and colleagues noted that those reporting sex with HIV-infected partners had increased odds of achieving protective concentrations at week 48.
“Our results showed high amounts of retention, engagement, and adherence to PrEP, supporting feasibility in a real-world setting in a middle-income country,” Grinsztejn and colleagues observed.
“The fact that early adherence was predictive of sustained adherence in the long term implies that interventions to improve adherence could be targeted to particular subgroups of PrEP users. Prompt identification of those who most need adherence support could enhance PrEP’s effectiveness."
Study participants were also invited to join a substudy that looked at the impact of interactive text messages on medication adherence. Among MSM aged 18—24 years, text messaging had a positive impact on medication adherence, highlighting 1 potential strategy for improving PrEP adherence.
The study, “Retention, engagement, and adherence to pre-exposure prophylaxis for men who have sex with men and transgender women in PrEP Brasil: 48 week results of a demonstration study,” was published this month in The Lancet HIV.
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