BASHH | HIV post-exposure prophylaxis following sexual exposure

HIV post-exposure prophylaxisThis guideline looks at the use of Post-Exposure Prophylaxis (PEP) following sexual exposure. For information on the use of PEP following occupational exposure, the following advice is helpful.

This isn’t something we’re going to come across very often. This is an excellent resource if faced with an affected patient. It gives tables with risks from different exposures (eg anal sex vs sharing needles etc) and the chance of the source being HIV positive depending upon their sexuality and the area they are from, when their status is unknown.

Risk of HIV transmission = risk that source has HIV (where status is unknown) x risk following exposure.

Where the source is known to be HIV positive, the risk of transmission is equal to the risk following exposure.

Generally you should be seeking advice and ideally patients should be referred to GU. However PEP is only indicated in the first 72 hrs after the exposure and the earlier it is started, the more effective. Starter packs should be available (eg from A&E) whilst the person is waiting to see GU. The guideline does talk through the advised regimes / drug interactions and side-effects.

PEP is normally indicated if

  • The risk of transmission is 1 in 1000 or more
  • Unprotected receptive anal intercourse with someone of unknown HIV status from a high risk group or area.
  • Unprotected insertive anal intercourse with someone known to be HIV positive with a detectable viral load.

PEP should be considered if

  • The risk of transmission is 1 in 1000 to 1 in 10000.
  • Risk may be increased by assault, the presence of STDs, break in the mucosal membranes (eg ulcers) and by active bleeding.

PEP would not normally be used if

  • Needlestick injuries in the community. This is because the risk of transmission is felt to be very low. The status of the source is unknown, whether the needle has actually been used is unknown and if it has been used, then the time since use of the needle is unknown. Most importantly, HIV normally has a short life in dried blood (eg 2 hrs).
  • Human Bites. Infection risk is likely to be very low.
  • Anxiety – PEP has lots of side-effects and there are risks with its use, so use solely because of the patient’s anxiety, would not be appropriate.

Other things to consider in the presenting patient

  • STD screening.
  • Pregnancy.
  • Baseline HIV testing and follow-up (normally done by GU)
  • Encouraging testing of the source if possible so that the risk can be better evaluated.
  • Future episodes / safe sex practices / need for early presentation after an exposure.
  • Evidence suggests that take-up of PEP is low, so advise at risk populations of its use and how to access it and the need to do so as soon as possible after exposure.

Louise Hudman

I'm a freelance GP locum in Winchester & Southampton locum chambers, and Pallant Medical Chambers Clinical Guidelines Lead Partner.

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