Preexposure prophylaxis decreases HIV infection in persons at high risk


  • Daniela Ovadia — Agenzia Zoe
  • Medical News
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Key messages

  • In adults at increased HIV-infection risk, preexposure prophylaxis (PrEP) with oral tenofovir disoproxil fumarate monotherapy or tenofovir disoproxil fumarate/emtricitabine is associated with decreased risk of acquiring HIV, compared with placebo or no PrEP.
  • Greater adherence to PrEP is associated with greater efficacy (risk reduction ~75% for adherence ≥70%).
  • Results were used by the United States Preventive Services Task Force for a new recommendation on PrEP for the prevention of HIV infection.

 

PrEP involves the use of antiretroviral therapy daily, or before and after possible HIV exposure events (sex, injection drug use) to decrease the risk of acquiring HIV infection. It could represent an effective prevention strategy in public health.

In this review, authors synthesised the evidence investigated in previous studies, on the benefits and harms of PrEP and the instruments for predicting incident HIV infection and PrEP adherence, in persons at increased risk for HIV (men who have sex with men, transgender women, people who inject drugs or in cases of heterosexual contact).

The systematic review included 14 randomised clinical trials, 8 observational studies, and 7 studies of diagnostic accuracy.

11 trials (18,172 participants) evaluated the role of PrEP (oral tenofovir disoproxil fumarate monotherapy or tenofovir disoproxil fumarate/emtricitabine) with follow-up duration ranging from 4 months to 4 years. PrEP was associated with reduced risk of HIV infection vs placebo or no PrEP (relative risk [RR] 0.46; absolute risk reduction [ARD] -2.0%).

The analysis of 6 trials (n=7,328) showed that greater adherence (≥70%) was associated with greater efficacy (RR 0.27).

Compared with placebo, PrEP was associated with an increased risk of renal adverse events (12 trials [n=18,170]; RR 1.43; ARD 0.56%) and gastrointestinal adverse events (12 trials [n=18,300]; RR 1.63; ARD 1.95%), but not of risk of fracture or other infections. However, most adverse events were mild and reversible.

All instruments for predicting incident HIV infection require further validation since they had moderate discrimination power.

Studies on US men who have sex with men showed that adherence varied widely (22%-90%) and was generally lower in younger men (16-20 years).

This report was commissioned by the United States Preventive Services Task Force, to develop a new recommendation statement on PrEP for the prevention of HIV infection in persons at increased risk.

Limitations: non-English-language articles were excluded; probable bias due to small sample effects; generalisability in the US, of both heterosexual people and persons who inject drugs is limited because trials in these populations were conducted in Africa or in Asia.