RT Journal Article SR Electronic T1 P543 Cost-effectiveness of pre-exposure prophylaxis in MSM with event-driven and daily regimens JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP A245 OP A245 DO 10.1136/sextrans-2019-sti.618 VO 95 IS Suppl 1 A1 Maarten Reitsema A1 Albert Jan Van Hoek A1 Maria Xiridou A1 Jacco Wallinga A1 Birgit Van Benthem A1 Ard Van Sighem A1 Maarten Schim Van Der Loeff A1 Maria Prins A1 Elske Hoornenborg YR 2019 UL http://sti.bmj.com/content/95/Suppl_1/A245.2.abstract AB Background Pre-exposure prophylaxis (PrEP) is highly effective in reducing HIV transmission among men who have sex with men (MSM). We investigated the impact of daily and event-driven PrEP on the transmission of HIV and N. gonorrhoeae (NG) and its cost-effectiveness in the Netherlands.Methods We developed a stochastic agent-based transmission model of HIV and NG among MSM. We simulated three scenarios: (1) No PrEP; (2) Offering daily and event-driven PrEP; (3) Offering only daily PrEP. Three-monthly PrEP monitoring included testing for HIV, gonorrhoea, and other infections. From the Amsterdam PrEP Demonstration Project (AMPrEP) data, it was estimated that 27% of PrEP users prefer event-driven PrEP and they use half the amount of PrEP pills used by daily users. We assumed PrEP effectiveness was 86% regardless of regimen. Simulated outcomes of the transmission model were used in an economic model to calculate costs, quality-adjusted life-years (QALY), and incremental cost-effectiveness ratios (ICER), over 2018–2027, taking a healthcare payer perspective. An ICER less than €20,000 per QALY gained was considered cost-effective.Results PrEP resulted in 3,486 HIV infections averted and 1,482 QALYs gained over 2018–2027. Gonorrhoea prevalence dropped from 0.782% in 2017 to 0.023% in 2027. When offering both daily and event-driven PrEP, the costs for PrEP medication were €19 million over 2018–2027. This resulted in less total costs than when no PrEP is offered, making this programme cost-saving. With only daily PrEP, the costs for PrEP medication were €22 million over 2018–2027, making this programme cost-effective with a mean ICER of €217.40 per QALY gained.Conclusion The PrEP programme (including STI monitoring) can be effective in reducing HIV incidence and gonorrhoea prevalence among MSM and can be cost-effective, even if all PrEP users prefer the daily regime. Monitoring of PrEP users can result in reductions in prevalence of STIs being monitored. Acknowledgements: AIDSfonds (2014037), ZonMw (522002003).Disclosure No significant relationships.