There are also precautions to be considered before initiating PrEP (Section 2, Graphic 8). All individuals should have a documented HBV and HCV infection status. Unvaccinated patients who are susceptible to HBV should be vaccinated. Tenofovir/emtricitabine is active against HBV, and it is important to know whether a subject has HBV prior to starting PrEP because HBV could flare up if treatment is started and then stopped. [USPHS 2014 PrEP guidelines 2014] Caution should also be used when considering the treatment of adolescents. Although PrEP is being studied in adolescents, no trials to date have included persons younger than 18 years of age. At this point in time, there are limited data on the effectiveness of PrEP in this age group or on potential safety issues, such as effects on bone in individuals who are still growing.[USPHS PrEP 2014 ] Pregnancy is another potential issue. PrEP use may continue during periconception and pregnancy and may help prevent transmission in the absence of other protective measures. However, data directly related to the safety of PrEP in the developing fetus are limited, so it is essential that the patient be involved in the decision to continue PrEP during conception or pregnancy. [USPHS PrEP guidelines 2014] Additional important precautions are shown in the following table.
Section 2, Graphic 8. PrEP contraindications and precautions.[adapted from USPHS PrEP guidelines 2014 PrEP guidelines]
PrEP Follow-up and Counseling
Counseling is a vital component of PrEP. Some of the key points that should be covered include:
- How it works and part of a comprehensive prevention plan (barrier protection, risk reduction, needle exchange, etc)
- Limitations: adherence dependent, not protective against other STIs, doesn’t eliminate risk
- Medication counseling: proper way to take, side effects, reason for limited refills
- Time until protection is achieved: need at least 7 days of daily dosing for rectal protection, 20 days for vaginal
- Follow-up and laboratory testing
- Symptoms of seroconversion/acute retroviral syndrome
- Criteria for discontinuing PrEP
The US Public Health Service/CDC guidelines recommend a number of tests that should be performed at baseline and periodically throughout PrEP, including testing for HIV and STIs, as shown below.
Section 2, Graphic 9. Clinical screening, follow-up, and monitoring during PrEP. Adapted from the US Public Health Service/CDC PrEP guidelines.[USPHS PrEP guidelines, 2014]
This rather extensive list of monitoring requirements can be quite time-consuming during a clinical visit. Tools to save time in the PrEP clinic include asking patients to perform their own triple swabs (oral, and rectal, see the Figure below), provide their urine samples; having a nurse or support staff member assist with obtaining the patient’s required blood work before the visit, utilizing a social worker or pharmacist for support counseling (including counseling on adherence and substance abuse), and creating templates for notes/checklists using the CDC guidelines.
Section 2, Graphic 10. San Francisco City Clinic patient instructions for performing oral and rectal swabs. [Pharyngeal swab 2017; Rectal self-swab 2017][Permission on request]
There are several reasons that a patient may discontinue PrEP, including an HIV-positive test or high clinical suspicion of acute retroviral syndrome, intolerable toxicity such as development of renal disease, chronic non-adherence, or lifestyle changes resulting in reduced risk of HIV transmission. If the person wishes to resume PrEP at a later time, they should undergo all of the pre-prescription evaluations recommended for a person being considered for a new prescription.
PrEP to PEP and Vice Versa
For patients who are adherent to PrEP, there is usually no need to intensify treatment by switching to PEP in the case of a serious exposure.[Grant and Smith 2015] However, treatment intensification could be considered if the patient takes PrEP sporadically.[Grant and Smith 2015] Dr Goldschmidt also recommends considering intensified treatment if serious exposure occurs during the first month of PrEP.
But what about going from PEP to PrEP? According to Dr Goldschmidt, persons at risk for HIV infection can be transitioned from PEP to PrEP if the repeat HIV test at 4 weeks is negative. False positives are a concern; if the patient has been adherent to PEP, the virus, if present, will likely be suppressed. Accordingly, the patient should be tested with both a 4th-generation HIV test and a test for viral load (HIV RNA), the laboratory marker that appears the earliest during HIV infection (see Section 1, Graphic 4).[Grant and Smith 2015] In addition, tests for STIs, renal and hepatic function, and pregnancy should be performed as for any patient initiating PrEP (see Section 2, Graphic 9).
High-risk persons should be transitioned from PEP to PrEP immediately at the end of the 28-day treatment period.[Grant and Smith 2015; University of California, San Francisco Clinician Consultation Center 2016] Although it is possible they may have an as-yet undetected HIV infection, the enhanced protection offered by a seamless transition to PrEP likely outweighs the potential risk of beginning PrEP with an HIV-positive status, which is contraindicated. Low-risk persons can wait to initiate PrEP until absence of HIV infection is fully confirmed.[University of California, San Francisco Clinician Consultation Center 2016] PEP should be re-instituted if there is a new exposure.
Primary care providers have readily available tools to assess the risk of HIV transmission. It is important to make sexual history a priority during healthcare encounters and understand the key HIV risk groups, including MSM and individuals with STIs or substance abuse problems. These are your patients—discussing risk behaviors can be challenging, but it is definitely worth it given the opportunity to prevent infection. Both PEP and PrEP have been demonstrated to be highly effective, but adherence is critical. Resources are available in your community to support PrEP and help prevent HIV transmission in your high-risk patients.