Table 4.

Effects of PrEP on STIs.

Study name	Outcome	Description
RCTS: PrEP vs. No PrEP
PROUD-pilot phase	STI	Proportion with confirmed rectal chlamydia/gonorrhea was similar in immediate (29%) and delayed (27%) (p = 0.50) arms.
OBSERVATIONAL STUDIES: CHANGE DURING PrEP USE or COMPARISON BETWEEN PRE/POST PrEP
iPrEx OLE	Syphilis incidence	Syphilis incidence was similar among PrEP users and non-users (HR 1.35, 95 CI 0.83–2.19). PrEP no-user:7.2 infections per 100 PY, PrEP no-user:5.4 infections per 100 PY
Ipergay OLE	Incidence of first bacterial STIs	Remain stable from 49.1 per 100 PY (95% CI 41.6–57.6) at RCT phase to 59.0 per 100 PY0 (95% CI 50.1–69.0) at open phase (p = 0.11)
KPSF	Multiple STIs	STIs: 187/657 PrEP initiators: at least 1 STI during follow-up; 78/657 PrEP initiators: multiple STIs (range 2–10); after 6 months of PrEP use, 30% of PrEP users with any STI (95% CI 26–35%), after 12 months of PrEP use, 50% of PrEP users with any STI (95% CI 43–56%)
NCT01632995	Multiple STIs	Overall STI incidence:90 per 100 PY (81–99); incidence remain stable across quarterly (p > 0.1)
PATH-PrEP	STI	STI:177(46.4%) participants with 175 STIs over 48 weeks follow-up, with a parabolic distribution over the follow-up phase (Baseline = 20.3%, 24 weeks = 17.7%,48 weeks = 28%)
ATN110YSMS	STI	Decreased from 76.48/100 PY at first 24 weeks to 60.99/100 PY in the latter 24 weeks

STI, sexual transmitted infection, PY, person years.