Effectiveness and medication adherence of daily and event-driven pre-exposure prophylaxis regimens among Chinese men who have sex with men: a real-world CROPrEP study


BACKGROUND: HIV protection data were scarce between daily and event-driven regimens of pre-exposure prophylaxis (PrEP) among men who have sex with men (MSM). We sought to evaluate the effectiveness and adherence of PrEP in the real-world study setting.
METHODS: From December 2018 to October 2020, PrEP was offered to MSM with a self-chosen regimen of daily or event-driven TDF/FTC in four Chinese cities Beijing, Shenyang, Chongqing and Shenzhen. PrEP initiators were followed up on 3-month intervals for 12 months. Medication adherence was measured by the reported proportion of covered sex acts by PrEP. MSM who were unwilling to initialed PrEP from local metropolis were provided parallel follow-up. HIV Incidence Risk Index for MSM (HIRI-MSM) was employed to evaluate the baseline HIV risk. Poisson regression was used to analyze the HIV incidence rate ratio (IRR) for assessing PrEP regimens'' effectiveness.
RESULTS: Of 1023 MSM who initiated PrEP (median age 29 years; median HIRI score 18, IQR: 12-22), 520 chose using daily dosing regimen and 503 chose using event-driven regimen. Meanwhile, 507 local MSM were PrEP non-users (median age 33 years; median HIRI score: 12, IQR: 7-18). Overall, 88% (904/1023) of PrEP users and 89%(452/507) of the non-users completed the 12-month follow-up, respectively. The proportion of covered sex acts by PrEP'¥90% increased over time in event-driven PrEP users (from 57% to 78%, p<0.001 for trend), while the opposite trend was observed in the daily group (75% to 72%, p=0.025 for trend). The overall HIV incidence was 0.64 per 100 person-years(PY) among PrEP users and 0.90/100PY in daily regimen users and 0.37/100PY in event-driven regimen users, which were both lower than that among nonusers (5.10/100PY, P<0.001). There is overall 87% reduction in incidence (aIRR: 0.21, 95% CI: 0.08-0.55) (daily PrEP aIRR 0.10; event-driven PrEP aIRR: 0.05) after adjusted for HIRI score and age.
CONCLUSIONS: This real-world study showed that PrEP can effectively reduce HIV risk among MSM. Compared with the traditional daily medication regimen, the event-driven regimen has increased trend of medication adherence and a better HIV protective effect.