Study: PrEP Adherence Curbs HIV Transmission in Straight Couples in Uganda

A study of HIV-negative heterosexuals who followed instructions for pre-exposure prophylaxis (PrEP) therapy indicated that PrEP was successful in preventing HIV. The researchers studied 1,147 HIV-negative individuals in long-term stable heterosexual relationships (average length of relationship was 8.5 years) with HIV-infected partners. Participants were from three Ugandan sites of the Partners PrEP study, which provided them with either Viread (tenofovir) or Truvada (tenofovir/emtricitabine). The group had six months of follow up left in the trial, had a median age of 34 years, and was 53 percent male.

Researchers tracked PrEP adherence by electronic pill bottle monitoring and unannounced home visits to count pills. Participants received counseling if adherence dropped below 80 percent.

Study participants had exceptional adherence levels, with an average of 99 percent for in-home pill counts and 97 percent for electronic monitoring. Of 404 individuals who received placebo, 14 were infected with HIV whereas of the 750 individuals who received PrEP, none was infected.

Researchers concluded that PreP could be very effective in preventing HIV transmission when recipients maintained their daily dosing schedule.

The full report, "Adherence to Antiretroviral Prophylaxis for HIV Prevention: A Substudy Cohort Within a Clinical Trial of Serodiscordant Couples in East Africa," was published in the journal PLOS Medicine (2013;doi/10.1371/journal.pmed.1001511).