Implications of HPTN 052 for standards of prevention in serodiscordant couples (part I)

HPTN 052 recently found that, in stable relationships consisting of an HIV positive partner and an HIV negative partner ("serodiscordant couples"), early antiretroviral treatment of the HIV+ partner dramatically reduces transmission of the virus. These study data support the idea that "test and treat"--identifying and treating HIV+ individuals as early as possible, post-infection--will reduce HIV transmission rates on a community level. Of course, an important question is whether the will and resources exist even to implement this strategy in the U.S., let alone in lower-resource settings where HIV incidence is higher.

While the public health implications of this research raise numerous ethical issues (which may be considered later on this blog), here's a research ethics question: among serodiscordant couples, does early treatment of the HIV+ partner now represent the correct standard of care? This question could affect other studies among serodiscordant couples, especially the Gates Foundation's Partners PrEP study. In Partners PrEP, SD couples are randomized such that in two thirds of the couples, the HIV- partner receives oral PrEP--that is, taking antiretroviral pills for prophylaxis. In the control group, the HIV- partner receives a placebo. In all of these couples, the HIV+ partner was enrolled at a CD4 count where he/she was not eligible for ART under national guidelines (although the couple stays on-study if the HIV+ partner becomes eligible for ART and begins taking it).

Therefore, many Partners PrEP participants, whose CD4 counts are in the range where 052 found a 96% reduction in transmission from treating the HIV+ partner, are not receiving ARVs. In the experimental groups of the study, the HIV- partner is receiving an intervention which has shown effectiveness in preventing incidence among men who have sex with men (the iPrEx study) but not among heterosexual women (FHI stopped the FEM-PrEP study in April due to futility). The placebo group will be receiving no intervention.

This issue represents a twist on the "standards of prevention" problem that is vexing HIV prevention researchers: once a new modality is known to be effective for HIV prevention, is it ethically acceptable to conduct a study which withholds that modality from any study participants? The Declaration of Helsinki seems to prohibit this practice, and recent HIV prevention trials have provided a comprehensive "background package" of all known effective interventions (condoms, risk reduction counseling, etc.). So, suppose WHO issues a strong recommendation based on the 052 data, recommending that serodiscordant couples should start early treatment of the HIV+ partner whenever possible. Is Partners PrEP unethical?