Trial design and measures
SELPHI recruited MSM (cis/trans) and trans women with self-reported HIV negative/unknown status, who reported lifetime anal sex with men, through sexual networking apps and social media (February 2017 to March 2018). Data for all trans participants are reported separately.Trial Consolidated Standards of Reporting Trials (CONSORT) flow diagram.A total of 10 111 MSM completed baseline questionnaires, which included an HIV risk assessment, and were individually computer randomised 60/40 to receive one baseline HIVST (baseline testing, BT) versus no baseline HIVST (no baseline testing, nBT) (randomisation A). Participants in BT received a survey at 2 weeks and at 3 months, in nBT participants received a survey at 3 months. A final exit survey (18 months after enrolment) asked whether using HIVST or being in SELPHI led to negative impacts on relationships (family, partners, friends, coworkers), or negative impacts on well-being, and whether since joining SELPHI participants had been pressured or persuaded to HIV test when they did not want to.Randomisation B occurred 3 months after randomisation A. Participants in BT who reported using the baseline HIVST, condomless anal sex with ≥1 male partner in previous 3 months and interest in further HIVST were randomised 50/50 to repeat three-monthly HIVST (repeat testing, RT) versus no repeat testing (nRT). RT participants received a survey 2 weeks after each HIVST delivery. nRT and RT participants received a regular survey every three months including a risk assessment. An exit survey (24 months after enrolment) included questions about harms.In intervention arms (BT, nRT and RT), false positive results could be reported on the 2-week, 3-month and regular surveys (in RT). All participants were asked about false positive results from self-tests (provided by SELPHI and sourced elsewhere) at end of study surveys acknowledging that HIVST was available sporadically through pilot projects during follow-up and commercially at cost throughout.