In sub-Saharan Africa, couples in long-term relationships where one partner is HIV-positive and the other is HIV-negative (HIV serodiscordant couples) could benefit from anti-AIDS drugs (antiretroviral therapy) given either as treatment or as a prevention measure (prophylaxis) to reduce the risk of HIV transmission. These findings, from a modelling study led by Timothy Hallett from Imperial College London and published in this week's PLoS Medicine, also show that this strategy could be cost-effective.

In sub-Saharan Africa, where most new HIV infections occur and condom use is often low, 10% of stable partnerships are serodiscordant. The authors used detailed information and specific data from South Africa to construct a model to simulate HIV infection and disease progression among hypothetical HIV serodiscordant couples in stable heterosexual relationships. The authors used the model to compare the impact on , survival and quality of life and the cost-effectiveness of different prophylaxis strategies.

To keep couples alive without the HIV-uninfected partner becoming infected, the authors found that it could be at least as cost-effective to provide prophylaxis to the uninfected partner as to initiate antiretroviral therapy earlier than current guidelines in the infected partner. Specifically, the most cost-effective strategy for couples could be to use prophylaxis in the uninfected partner prior to starting antiretroviral therapy in the infected partner.

These findings suggest that prophylaxis may become a valuable addition, in some settings, to existing approaches for HIV prevention such as condom promotion, programs and anti-retroviral treatment.

The authors say: "We hope [these findings] might inform the choices that will be available for in couples. We note, however, that it is important that many other considerations besides cost effectiveness should inform decision-making for initiation and provision of [prophylaxis] in couples, including equitable access and the preferences of the couples themselves."

More information: Hallett TB, Baeten JM, Heffron R, Barnabas R, de Bruyn G, et al. (2011) Optimal Uses of Antiretrovirals for Prevention in HIV-1 Serodiscordant Heterosexual Couples in South Africa: A Modelling Study. PLoS Med 8(11): e1001123. doi:10.1371/journal.pmed.1001123