Background: On-demand PrEP with TDF/FTC has been recommended as an alternative to Daily PrEP for MSM by the European AIDS Clinical Society following the results of clinical studies but data are limited on real-world experience.
Methods: The ANRS Prevenir study is an ongoing prospective cohort study in the Paris region enrolling high risk individuals willing to/or using PrEP. Both daily and On-demand PrEP were offered to eligible individuals. At baseline, month 1 and every 3 months thereafter subjects were tested for HIV using a 4th generation combined ELISA test and other STIs and creatinine plasma levels were monitored. At each visit participants provided information regarding sexual behaviour and adherence using computer assisted self-interviews. Analysis of HIV incidence was assessed to provide additional data on the efficacy and safety of the two PrEP dosing regimens.
Results: From May 3rd 2017 to May 1st 2018, 1435 subjects were enrolled across 22 sites, 59% being PrEP experienced for a median of 10 months. Median age was 37 years (IQR: 30-44), 98.7% were MSM. At enrolment, PrEP was used Daily in 44% and On-demand in 53% of participants. Median number of partners in the 3 months before enrolment was 15 (IQR: 7-25) in the Daily group and 10 (5-15) in the On-demand group (P< 0.001). Median number of condomless sex in the prior 4 weeks was 3 (1-8) and 2 (0-4), respectively, P< 0.001. The current follow-up lasted 302 and 361 person-years (PY) in the Daily and On-demand groups, respectively. The incidence of HIV-1 infection was 0 (95% CI: 0-1.2) per 100 PY and 0 (95% CI: 0-1.0) in the Daily and On-demand groups respectively (P=1.00) and the incidence of study discontinuation was 3.0 and 3.6 per 100 PY (P=0.674) respectively, including 1.3 and 1.1 per 100 PY drop out of PrEP because participants no longer feel at risk. No participant discontinued PrEP for drug-related adverse events.
Conclusions: In this ongoing PrEP cohort in Paris region, enrolling mainly MSM at high risk of HIV-acquisition, no breakthrough HIV-infection was reported so far with either daily or on-demand PrEP, supporting continuing use of both dosing regimens in this population.