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No HIV Infections in PrEP Adherers,
But Only 56% Continue PrEP 5 Years

  AIDS 2020: 23rd International AIDS Conference Virtual, July 6-10, 2020
Mark Mascolini
Through 12,810 person-years of follow-up among people adherent to PrEP in the Kaiser Permanente healthcare system, no one picked up HIV infection [1]. But only a little more than half of the study population continued PrEP through 5 years, and 1.5% of those who quit PrEP got HIV infection.
PrEP is highly effective in preventing HIV infection among people who take their PrEP drugs consistently while remaining at risk for HIV infection. Kaiser Permanente researchers who conducted this study noted that many people do not clear successive hurdles in the PrEP continuum of care, defined here as linkage to PrEP care, PrEP prescription, PrEP initiation, and persistent PrEP use.
This analysis focused on adult members of the Kaiser Permanente Northern California system linked to PrEP care between July 16, 2012 and March 31, 2019. The Kaiser team defined PrEP linkage as a PrEP referral or clinical encounter, PrEP prescription as a prescription written by a provider, PrEP initiation as a pharmacy fill within 6 months of linkage, and PrEP persistence as fewer than 120 days elapsing since the last day of PrEP possession based on pharmacy fills. The investigators analyzed persistence among people enrolled in Kaiser for at least 6 months. They used unadjusted log-binomial regression to pinpoint factors linked to steps in the continuum.
Almost all study participants, 95%, were men, 50% were white, 21% Hispanic, 15% Asian, and 7% African American. African-American participants were significantly less likely (1) to receive a PrEP prescription (risk ratio [RR] 0.87, 95% confidence interval [CI] 0.83 to 0.91) or (2) to begin PrEP (RR 0.81, 95% CI 0.76 to 0.86) and more likely to stop PrEP (RR 1.18, 95% CI 1.04 to 1.34).
The researchers counted 12,963 people linked to PrEP care, 10,310 (79.5%) prescribed PrEP, 8571 (66%) who began PrEP, and 6257 (48%) who continued PrEP for at least 1 year. Through 12,810 person-years of PrEP use (average 1.9 years/person), 73% stayed on PrEP for 1 year, 64% for 2 years, 60% for 3 years, 57% for 4 years, and 56% for 5 years. Among 2525 people not persistent on PrEP, 932 (37%) resumed PrEP.
Through the recorded PrEP continuum, 136 people acquired HIV infection. Notably, among those linked to PrEP care who never got a prescription, 37 people (1.4% of 2653) picked up HIV infection. And among people who stopped PrEP, 38 (1.5% of 2525) got infected after stopping. Forty-two people (0.32% of 12,963) got diagnosed with HIV infection at PrEP linkage, 13 people (0.75% of 1739) acquired HIV after getting a PrEP prescription but before starting PrEP, and 6 people (0.14% of 4238) got diagnosed with HIV while remaining persistent on PrEP-but all 6 of them reported suboptimal PrEP adherence.
The Kaiser team concluded that PrEP persistence remained fairly stable over time, with the biggest dropoff coming in the first year. They noted that African Americans ran a higher risk of falling off the PrEP continuum at three points. The investigators underlined opportunities for targeted intervention at two missteps in the continuum where a high proportion of people got infected with HIV: linked to care but never getting a prescription, and discontinuing PrEP. They stressed that through 12,810 person-years among people adherent to PrEP, no one got HIV infection.
1. Volk JE, Hojilla JC, Hurley L, et al. PrEP continuum of care and new HIV infections: Long-term follow-up in a large clinical cohort. AIDS 2020: 23rd International AIDS Conference Virtual. July 6-10, 2020. Abstract OAC0807.