Comparison between daily and on‐demand PrEP (pre‐exposure prophylaxis) regimen in covering condomless anal intercourse for men who have sex with men in Hong Kong: A randomized, controlled, open‐label, crossover trial

Abstract

<p><strong>Introduction: </strong>Both daily and on-demand regimens have been proven effective for pre-exposure prophylaxis (PrEP) against HIV in men who have sex with men (MSM). We aimed to compare the two regimens on their coverage of condomless anal intercourse (CLAI) in MSM.</p><p><strong>Methods: </strong>A randomized, controlled, open-label, crossover trial was conducted in a teaching hospital in Hong Kong. Participants were sexually active HIV-negative MSM aged 18 years or above with normal renal function and without chronic hepatitis B infection. Oral tenofovir disoproxil fumarate 300 mg/emtricitabine 200 mg (TDF/FTC) tablets were prescribed for PrEP. After a 2-week lead-in with daily TDF/FTC for treatment-naïve MSM for tolerance assessment, participants were randomly assigned in a 1:1 ratio with a block size of four to either daily-first or on-demand-first arm based on the IPERGAY study, for receiving PrEP for 16 weeks, then crossed-over to the alternative regimen for another 16 weeks. The primary outcome was the proportion of days with PrEP-covered CLAI by intention-to-treat analysis. The trial is registered with the CCRB Clinical Trials Registry, CUHK, CUHK_CCRB00606, and is closed to accrual.</p><p><strong>Results: </strong>Between 25 August 2018 and 23 March 2019, 119 eligible participants were assigned to daily-first arm (n = 59) and on-demand-first arm (n = 60) with an 87% overall completion rate (n = 103). With 96% and 54% of days on PrEP during daily and on-demand periods, respectively, the proportion of days with PrEP-covered CLAI between two arms were not statistically different (92% vs. 92%, p = 0.93). About half (47%) were diagnosed with at least one episode of incident sexually transmitted infection. Mild and time-limited adverse events, including diarrhoea, headache, nausea and dizziness, were reported in 37 (31%) and 10 (8%) during the daily and on-demand periods, respectively. At the end of the study, a similar proportion favoured daily or on-demand regimen.</p><p><strong>Conclusions: </strong>High prevention-effective adherence, as reflected from the coverage of CLAI, was achievable by either daily or on-demand PrEP among MSM, albeit a higher number of tablets taken for daily PrEP. As both regimens were well accepted, a flexible approach adopting either or both regimens with possible switching is warranted in order to suit individual health needs.</p>