I wanted to also draw attention to the pivotal role of pill-use in the iPrEx results. About a year or so before the end of the study we developed, disseminated, and implemented a strengths-based, motivational-interviewing-advised approach to support pill-use among iPrEx participants that also involved the removal of the interview-based adherence assessment from the counseling session (pill-use discussion). What I think is clear in the iPrEx results, echoing what CAPRISA found as well, is that having the active drug in your system is (1) critical to improved prevention effects and (2) not as high as self-report would suggest. iPrEx made a dramatic move away from a messaging based approach to a motivational one in part because of concerns that the frequent messaging around taking a pill every day was promoting bias in self-presentation of reported adherence for some participants and was cutting short the possibility for frank conversations about difficulties and concerns surrounding pill-use.
I don’t know that we'll be able to cleanly assess the impact/effect of the introduction of this new pill-use support strategy (we call it Next Step Counseling) within iPrEx or the training on interview-based adherence assessment (Neutral Assessment) but lessons learned from the counselors and assessors to date been generally quite supportive. We are in the process of gathering more information, but in the meantime I wanted to emphasize that adherence in any PrEP trial is a critical factor-- it will set the upper limit of true efficacy. Many on-going biomedical HIV prevention trials are developing innovative ways to support study-drug use that go beyond providing information or messages. Certainly adherence is not the only factor-- there needs to be efficacy in the first place-- but it is a critical factor to keep in mind with any prevention strategy that require self-administration, self-directed adoption of the strategy. I think it is important that we as a community contribute to these conversations and innovations. PrEP adherence will differ in many ways from ARV therapy adherence, but we have a fair amount to offer here!
K Rivet Amico, PhD
Center for Health, Intervention and Prevention
University of Connecticut
810 360 8716
800 518 0243 (fax)
Summary: In this multinational study, called the Preexposure Prophylaxis Initiative (iPrEx) trial, researchers aimed to evaluate the safety and efficacy of once-daily oral FTC–TDF as compared with placebo for the prevention of HIV acquisition among men and transgender women who have sex with men.
Methods: We randomly assigned 2499 HIV-seronegative men or transgender women who have sex with men to receive a combination of two oral antiretroviral drugs, emtricitabine and tenofovir disoproxil fumarate (FTC–TDF), or placebo once daily. All subjects received HIV testing, risk-reduction counseling, condoms, and management of sexually transmitted infections.
Results: The study subjects were followed for 3324 person-years (median, 1.2 years; maximum, 2.8 years). Of these subjects, 10 were found to have been infected with HIV at enrollment, and 100 became infected during follow-up (36 in the FTC–TDF group and 64 in the placebo group), indicating a 44% reduction in the incidence of HIV (95% confidence interval, 15 to 63; P=0.005). In the FTC–TDF group, the study drug was detected in 22 of 43 of seronegative subjects (51%) and in 3 of 34 HIV-infected subjects (9%) (P<0.001). Nausea was reported more frequently during the first 4 weeks in the FTC–TDF group than in the placebo group (P<0.001). The two groups had similar rates of serious adverse events (P=0.57).
Conclusions: Oral FTC–TDF provided protection against the acquisition of HIV infection among the subjects. Detectable blood levels strongly correlated with the prophylactic effect.
Source: New England Journal of Medicine - NEJM
Publication Date: November 23, 2010
Keywords: iPrEx, pre-exposure Prophylaxis, Publications & Research, Sexual transmission