The study participants who received PrEP had their risk of HIV infection reduced by 86%, according to the study's authors.
Pre-exposure prophylaxis (PrEP) was found to reduce the risk of infection by 86% for this group during the PROUD study (Pre-exposure Option for reducing HIV in the UK: immediate or Deferred). The effects were so pronounced that a group of participants who had been deferred access to PrEP were offered the treatment ahead of schedule.
"These results are extremely exciting and show PrEP is highly effective at preventing HIV infection in the real world," says lead investigator Prof. Sheena McCormack. "Concerns that PrEP would not work so well in the real world were unfounded. These results show there is a need for PrEP, and offer hope of reversing the epidemic among men who have sex with men in this country."
For the trial, the researchers utilized the antiretroviral Truvada, a drug that has previously been demonstrated to reduce the incidence of HIV infection in placebo-controlled trials. In this new study, the researchers wanted to determine whether the drug would be similarly effective in a real-world situation.
Questions such as whether PrEP would affect sexual risk behavior and how cost-effective the treatment would be would also be addressed by the study.
Launching in 2012, a total of 545 participants were recruited from 13 sexual health clinics across England. Participants were randomly assigned into two groups - 276 participants began receiving PrEP immediately, and the other 269 would receive PrEP after 12 months.
A total of 22 HIV infections occurred among the participants during the first year of the study. Of these, 3 were in the group receiving PrEP and 19 were in the group whose access to PrEP was deferred. The researchers calculate that this gave the PrEP group an HIV incidence of 1.3 per 100 person-years, compared with 8.9 per 100 person-years in the deferred group.
In October 2014, the participants who had yet to begin PrEP were to be offered the medication earlier than planned, following a recommendation from the Independent Data Monitoring Committee based on an interim analysis of the data that had been accumulated up until that point.
PrEP 'could have a major impact in preventing HIV infection'
Behavioral data were also accumulated during the study. At the conference, the researchers suggested that sexual risk behavior was unaffected by PrEP. Reported condom use appeared similar both before and during the study, and no significant differences in the rates of STI infection between groups were observed.
Dr. Des Walsh, head of Infections and Immunity at the Medical Research Council (MRC) in the UK, says that HIV remains a serious public health concern and that new approaches are required to tackle what he describes as an "epidemic."
"The PROUD study addresses this very important issue and shows promising results that a relatively straightforward intervention based on existing therapy - PrEP - could have a major impact in preventing HIV infection," he states.
The results of the study are now to be submitted to a peer-reviewed journal. In addition, cost-effectiveness analyses are being conducted to see whether antiretrovirals for PrEP should be commissioned for use by the British National Health Service.
Dr. Richard Gilson, a principal investigator for the PROUD study, works at a sexual health clinic in central London in the UK. He believes that there are many high-risk men who have sex with men who would be willing to take PrEP tablets regularly to reduce their risk of infection:
"This will not suit everyone, and may not be needed indefinitely, but for at least some individuals for some of the time it should be considered as an important additional measure that will help to reduce the persistently high rate of new infections that we are still seeing."
Recently, Medical News Today reported on a study stating that 41,000 HIV transmissions in the US every year are attributable to a lack of diagnoses and care.