PrEP Is Highly Effective; How Can We Increase Adoption?

Rona M. Vail, MD


June 25, 2020

Numerous studies have found that when taken consistently, preexposure prophylaxis (PrEP) is 99% effective in preventing sexually transmitted HIV in men who have sex with men (MSM), heterosexual men, and women. There are fewer data regarding the use of PrEP to prevent HIV in people who inject drugs, with just one study reporting efficacy of 74%-89%.

Despite its effectiveness, PrEP uptake and retention in care are surprisingly low among those who are at highest risk of acquiring HIV. Uptake rates are lower among black and Latino MSM, black women, and transgender women, whereas 75% of PrEP prescriptions have been written for white MSM. Retention is also surprisingly low, with just 57% of patients who start PrEP still taking it 6 months later.

The Medical Care Criteria Committee of the New York State Department of Health (NYSDOH) AIDS Institute (AI) published an update to its guideline PrEP to Prevent HIV and Promote Sexual Health. This update incorporates recent data, promotes same-day initiation, and presents an individualized and flexible approach to expand PrEP use and improve retention. An important goal of this guideline update was to address some of the barriers to PrEP access, uptake, and retention, including the effects of stigma, delays in initiation, uniformly inflexible dosing schedules, and onerous follow-up requirements.

Same-Day Initiation Is Best When Possible

The guideline recommends same-day PrEP initiation for individuals without known hepatitis B, known renal disease, and signs or symptoms of acute HIV, or with an exposure within the past 72 hours requiring postexposure prophylaxis, as long as initial laboratory results will be received and acted upon within 7 days.

Same-day PrEP initiation after initial medical assessment has been found to be safe. When initiation was delayed, loss to follow-up was significant, with only 35% of people who were eligible for PrEP starting it within 60 days. If a person is diagnosed with HIV subsequently, then the PrEP regimen can be intensified immediately to a full HIV treatment regimen and the patient referred for HIV care.

Daily Dosing Is Optimal, On-Demand Is Possible for Some

On-demand or intermittent dosing of tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) as PrEP has been shown to be an effective option for MSM. Therefore, although daily dosing of PrEP remains the preferred dosing strategy, the updated guideline now allows on-demand dosing of TDF/FTC as an option for cisgender MSM.

This dosing strategy is not recommended, however, for individuals who engage in receptive vaginal sex or individuals who inject drugs because of a lack of data. On-demand PrEP has not been studied for vaginal or injection exposure, and there is evidence that more frequent dosing is required for effectiveness for these routes of exposure.

Until further data are available, on-demand dosing is also not recommended for transgender women on estrogen therapy because estrogen can decrease tenofovir levels. On-demand dosing is also not appropriate for individuals with hepatitis B virus infection.

Flexibility Is Key to Retention

The NYSDOH AI guideline previously recommended that all individuals taking PrEP have in-person follow-up visits every 3 months for HIV and other laboratory testing. This follow-up schedule had the effect of burdening otherwise healthy individuals with more required clinical appointments than for patients with almost any other medical condition, including HIV. Mandatory quarterly visits could be significantly disruptive to the lives of people on PrEP.

To reduce this disruption, the updated guideline now recommends in-person visits just once or twice per year for individuals who are stable on PrEP. Quarterly HIV testing and screening for sexually transmitted infections (STIs) are advised as good practice to prevent development of resistance in the case of HIV acquisition and to promote regular STI screening—but this is not an evidence-based recommendation, so the committee advises flexibility.

The recommended quarterly HIV testing, STI screening, and twice-yearly monitoring of renal function can be accomplished with a visit to a laboratory at a location and time convenient for the patient, and review of results does not require an office visit.

There have been cases of HIV acquisition after denial of a medication refill as a result of a missed visit. Every effort should be made to avoid discontinuing PrEP or withholding it from a person who is at risk of acquiring HIV.

TDF/FTC Is Still Preferred for Most

There has been some concern about the effect of TDF on kidneys and bones, but the majority of adverse events have occurred with antiretroviral regimens that included the pharmacokinetic boosters ritonavir or cobicistat. Both of those boosters can increase tenofovir levels. However, a meta-analysis found no significant differences in laboratory or clinical safety outcomes between TDF/FTC and tenofovir alafenamide/FTC (TAF/FTC) when used for HIV treatment in a regimen without pharmacokinetic boosters. Another meta-analysis of studies of TDF/FTC for PrEP that included more than 22,000 individuals found TDF/FTC to be safe.

In 2019, the FDA approved the use of TAF/FTC to prevent HIV from sexual exposure in only cisgender men and transgender women; it is not recommended for prevention against HIV transmitted through receptive vaginal sex. Approval was based on the DISCOVER trial, which found TAF/FTC to be noninferior to TDF/FTC in preventing sexually transmitted HIV in MSM and transgender women. Both regimens were highly effective and well-tolerated, with more favorable biomarkers for renal and bone function in the TAF/FTC arm, although there were no significant differences in clinical safety outcomes.

Given the substantial amount of data establishing its efficacy and safety for all populations, the NYSDOH AI guideline recommends TDF/FTC as the preferred PrEP regimen. TAF/FTC is an option for preventing HIV through sexual exposure in MSM and transgender women and is the preferred PrEP regimen for MSM and transgender women who have preexisting renal disease and osteoporosis.

All Care Providers Can Play a Key Role in HIV Prevention

Although it is a highly effective strategy for preventing HIV, PrEP is not reaching those who need it the most. PrEP can and should be made available in as many clinical practice settings as possible, and all care providers can play a key role in expanding use of PrEP.

By routinely assessing individuals' risk of acquiring HIV, reducing barriers to PrEP access and use, and offering flexibility in follow-up, all care providers can help advance the goal of ensuring that everyone at risk can benefit from this effective HIV prevention method.

Rona M. Vail, MD, is an HIV specialist with over 25 years of experience. She serves on the New York State Department of Health AIDS Institute Medical Care Criteria Committee and Quality of Care Committee, as well as the New York City Mayoral Commission on HIV/AIDS.

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