In a well-designed and rigorously executed clinical trial, people living with HIV who started antiretroviral therapy had a significantly lower risk of transmitting the virus to their partners compared to those assigned to wait to start HIV treatment. This you all know; the trial was HIV Prevention Trials Network Study 052. What remained debatable was the extent to which this finding would be replicated in the real world.
This year, the results of the PARTNER study made clear that antiretroviral therapy as prevention works even outside a clinical research trial.
The study included 1,110 HIV serodiscordant couples in Europe, most of them heterosexual and about a third MSM, who do not use condoms. The HIV-infected partner had to have a plasma HIV RNA level <200 copies/mL on stable antiretroviral therapy. Safe sex counseling was provided and couples were followed up with every six months, with surveys of both and testing for HIV viral load (infected partner) and HIV antibodies (uninfected partner). However, analyses included periods when condoms and PrEP were not used.
As expected, there was a lot of sex going on in the study. During a median follow-up of 1.1 years in MSM, 1.5 years in heterosexual men, and 1.5 years in heterosexual women, the estimated total numbers of condom-free sex acts were 16,400, 14,000 and 14,000, respectively. This translates into 43, 37 and 37 condom-free sex acts per year for MSM, HIV-uninfected heterosexual men, and HIV-uninfected women, respectively. Self-reported nonadherence to antiretroviral therapy (defined as less than 90% adherence) among the infected partners was rare. However, other sexually transmitted infections (STI) were not, with 16% of MSM diagnosed with an STI, and 5% of heterosexuals.
During the follow-up period there were no transmissions that could be linked from the infected to the uninfected partner. This despite the abovementioned unprotected sex and even incident STIs.
The findings do not mean that transmission of HIV among those on effective therapy is impossible, and confidence intervals were placed around the results to make that clear. But, the study does suggest that current antiretroviral therapy is able to provide substantial protection against secondary transmission. Providers can now use these important data during those all too common discussions with their patients regarding risk.
What are some other top clinical developments of 2014? Read more of Dr. Wohl's picks.
David Alain Wohl, M.D., is an associate professor of medicine in the Division of Infectious Diseases at the University of North Carolina and site leader of the University of North Carolina AIDS Clinical Trials Unit at Chapel Hill.