Table 2.

Study characteristics

Study	Location	Population	Intervention	Comparison	Participants (n)	Follow-up (PYs)	Adherence: high (≥80%) vs low (<80%)*
MSM
Hosek et al (Project PrEPare)25	USA	MSM, median age: 20 years	TDF/FTC	Daily PrEP versus placebo or ‘no pill’	58	27	Low: 62% by self-report
Grohskopf et al (CDC Safety Study)20	USA	MSM, age range: 18–60 years	TDF	Immediate or delayed PrEP versus immediate or delayed placebo	400	800	Low: 77% by pill count
Grant et al (iPrEx)3	Brazil, Ecuador, South Africa, Peru, Thailand and USA	MSM (99%) and transgender women (1%), age range: 18–67 years	TDF/FTC	Daily PrEP versus placebo	2499	3324	Low: 51% by plasma drug detection
McCormack et al (PROUD)6	UK	MSM, median age: 35 years	TDF/FTC	Immediate PrEP versus delayed PrEP	544	504	High: 88% (self-report and plasma drug detection†)
Molina et al (IPERGAY)5	Canada and France	MSM, median age: 34.5 years	TDF/FTC	Intermittent (‘on-demand’‡) PrEP versus placebo	400	431	High: 86% by plasma drug detection
Mutua et al (IAVI Kenya Study)21	Kenya	MSM (93%) and female sex workers (7%), mean age: 26 years	TDF/FTC	Daily or intermittent PrEP versus daily or intermittent placebo	72	24	High: 83% by MEMS
Serodiscordant heterosexual couples (when the HIV-positive partner is not on antiretroviral treatment)
Kibengo et al (IAVI Uganda Study)22	Uganda	Serodiscordant couples (negative partner: 50% male), mean age: 33 years	TDF/FTC	Daily or intermittent PrEP versus daily or intermittent placebo	72 couples	24	High: 98% by MEMS
Baeten et al (Partners PrEP Study)18	Kenya and Uganda	Serodiscordant couples (negative partner: 61%–64% male), age range: 18–45 years	TDF/FTC and TDF only	Daily PrEP versus placebo	4747 couples	7830	High: 82% by plasma drug detection
Baeten et al (Partners PrEP Study Continuation)23	Kenya and Uganda	Serodiscordant couples (negative partner: 62%–64% male), age range: 28–40 years	TDF/FTC and TDF only	TDF/FTC versus TDF	4410 couples	8791	Low: 78.5% by plasma drug detection
Heterosexuals
Bekker et al (ADAPT Cape Town)24	South Africa	Women, median age: 26 years	TDF/FTC	Daily, time and event-driven PrEP	191	99	Low: 53%–75% by MEMS
Marrazzo et al (VOICE)19	South Africa, Uganda and Zimbabwe	Women, median age: 24 years	5 arms: TDF/FTC, TDF only, 1% TDF vaginal gel, oral placebo and placebo vaginal gel	Daily PrEP versus placebo	4969	5509	Low: 29% by plasma drug detection
Peterson et al 200717	Nigeria, Cameroon and Ghana	Women, age range: 18–34 years	TDF	Daily PrEP versus placebo	936	428	Low: 69% by pill count
Thigpen et al (TENOFOVIR2)16	Botswana	Heterosexual men (54.2%) and women (45.8%), age range: 18–39 years	TDF/FTC	Daily PrEP versus placebo	1219	1563	High: 84.1% by pill count
Van Damme et al (FEM-PrEP)7	Tanzania, South Africa and Kenya	Women, median age: 24.2 years	TDF/FTC	Daily PrEP versus placebo	2120	1407	Low: 24% by plasma drug detection
PWIDs
Choopanya et al (Bangkok Tenofovir Study)15	Thailand	PWID (80% male), median age: 31 years	TDF	Daily PrEP versus placebo	2413	9665	Low: 67% by plasma drug detection

In all cases, tenofovir dose was 300 mg and FTC dose was 200 mg.

*Adherence refers to the proportion of participants in trials that adhered to the study drug. In most studies, more than one method was used to measure adherence; taking a conservative approach, the trials used the lowest estimate of adherence. In trials that investigated daily and intermittent PrEP, adherence relates to daily PrEP. In studies that measured tenofovir and FTC separately, adherence refers to tenofovir detection.

†PROUD trial: adherence was determined by a combination of self-report and plasma drug detection. Sufficient study drug was prescribed for 88% of the total follow-up time, and the study drug was detected in 100% of participants who reported taking PrEP.

‡On-demand dosing: participants were instructed to take two pills of TDF/FTC or placebo 2–24 hours before sex, followed by a third pill 24 hours later and a fourth pill 48 hours later.

FTC, emtricitabine; MEMS, medication event monitoring system; MSM, men who have sex with men; PrEP, pre-exposure prophylaxis; PWID, people who inject drugs; PY, person-years; TDF, tenofovir disoproxil fumarate; TDF/FTC, tenofovir disoproxil fumarate and emtricitabine fixed-dose combination.