Table 1.
Baseline characteristics of the study subjects
| Median (interquartile range) or N (%) | ||||||
|---|---|---|---|---|---|---|
| TDF n=1584 |
FTC/TDF n=1579 |
Placebo n=1584 |
||||
| HIV-1 seronegative partner | HIV-1 seropositive partner | HIV-1 seronegative partner | HIV-1 seropositive partner | HIV-1 seronegative partner | HIV-1 seropositive partner | |
| Demographic Characteristics | ||||||
| Male sex | 986 (62%) | 598 (38%) | 1013 (64%) | 566 (36%) | 963 (61%) | 621 (39%) |
| Age, years | ||||||
| 18–24 | 184 (12%) | 268 (17%) | 177 (11%) | 287 (18%) | 172 (11%) | 273 (17%) |
| 25–34 | 721 (46%) | 657 (41%) | 690 (44%) | 636 (40%) | 688 (43%) | 629 (40%) |
| 35–44 | 480 (30%) | 474 (30%) | 498 (32%) | 460 (29%) | 513 (32%) | 509 (32%) |
| ≥45 | 199 (13%) | 185 (12%) | 214 (14%) | 196 (12%) | 211 (13%) | 173 (11%) |
| Education, years | 7 (4,10) | 7 (4,9) | 7 (4,10) | 7 (4,9) | 7 (4,10) | 7 (4,9) |
| Monthly income, any | 1275 (80%) | 1069 (67%) | 1236 (78%) | 1052 (67%) | 1259 (79%) | 1079 (68%) |
| Couple Characteristics* | ||||||
| Married to study partner | 1543 (97%) | 1540 (98%) | 1552 (98%) | |||
| Years living with study partner | 7.0 (3.0,13.5) | 7.1 (3.0,14.0) | 7.1 (3.0,14.0) | |||
| Number of children in partnership | 2 (1,4) | 2 (1,4) | 2 (1,4) | |||
| Proportion of couples without children | 343 (22%) | 368 (23%) | 342 (22%) | |||
| Years aware of HIV-1 serodiscordant status | 0.5 (0.1,2.0) | 0.4 (0.1,2.0) | 0.4 (0.1,2.0) | |||
| Sexual Risk Behavior* | ||||||
| Number of sex acts in prior month | 4 (3,8) | 4 (3,8) | 4 (3,8) | |||
| Any unprotected sex acts in prior month | 442 (28%) | 416 (26%) | 409 (26%) | |||
| Any sex with outside partner in prior month | 150 (9%) | 84 (5%) | 134 (8%) | 106 (7%) | 122 (8%) | 103 (7%) |
| Clinical Characteristics | ||||||
| CD4 cell count/mm3 | N/A | 491 (370,661) | N/A | 497 (380,664) | N/A | 499 (375,663) |
| HIV-1 plasma RNA, log10 copies/mL† | N/A | 3.9 (3.2, 4.5) | N/A | 3.9 (3.1, 4.5) | N/A | 3.9 (3.2, 4.5) |
| Circumcised (men only) | 533 (54%) | 198 (33%) | 540 (53%) | 177 (31%) | 509 (53%) | 202 (33%) |
| Using contraception‡ (women only) | 263 (44%) | 290 (29%) | 275 (49%) | 324 (32%) | 299 (48%) | 321 (33%) |
| Pregnant (women only) | 0 (0%) | 152 (15%)††† | 0 (0%) | 135 (13%) | 0 (0%) | 118 (12%) |
| Neisseria gonorrhoeae, Chlamydia trachomatis, or Trichomonas vaginalis **†† | 86 (6%)††† | 117 (8%) | 93 (6%)††† | 122 (8%) | 126 (8%) | 137 (9%) |
| Syphilis seropositivity††‡‡ | 59 (4%) | 73 (5%) | 60 (4%) | 52 (3%) | 62 (4%) | 73 (5%) |
| Herpes simplex virus type 2 seropositive*** | 835 (55%) | N/A | 814 (54%)††† | N/A | 875 (58%) | N/A |
Couple characteristics and sexual risk behavior within the study partnership were as reported by the HIV-1 seronegative partner.
Plasma HIV-1 RNA concentrations from enrollment samples were quantified in batch testing at the University of Washington using the Abbott Real-Time HIV-1 RNA assay (Abbott) at a limit of quantification of 80 copies/mL.
Any contraceptive use includes: hormonal oral, injectable and implantable contraceptives, intrauterine device, hysterectomy or bilateral tubal ligation. 83% of HIV-1 seronegative and 85% of HIV-1 seropositive women using contraception used a hormonal method.
Data were available from 98% of HIV-1 seronegative and 96% of HIV-1 seropositive participants. T. vaginalis was the most common infection, accounting for 75% of total infections detected. N. gonorrhoeae and C. trachomatis testing were by APTIMA Combo 2 (Gen-Probe) or COBAS Amplicor (Roche Diagnostics), and T. vaginalis testing was by APTIMA TV TMA (Gen-Probe) or In Pouch TV (Biomed Diagnostics).
Laboratory screening for asymptomatic curable infections was done at baseline and annually. Assessment for symptomatic sexually transmitted infections was conducted quarterly, or more frequently if clinically indicated. Participants were treated for symptomatic sexually transmitted infections and asymptomatic infections found as a result of scheduled screening.
Syphilis serologic testing was by rapid plasma reagin, confirmed by a treponema-specific assay.15 Seropositive results could indicate current or past infection.
Herpes simplex virus type 2 testing was done using the HerpeSelect-2 EIA (Focus Technologies) at enrollment only; an index value of ≥3.5 was used to define a positive result.39
Of 58 comparisons of enrollment characteristics for this table (i.e., 29 factors, including for HIV-1 seronegative and HIV-1 seropositive partners and for couples, and for TDF versus placebo and FTC/TDF versus placebo), four had p-values <0.05: prevalence of Neisseria gonorrhoeae, Chlamydia trachomatis, or Trichomonas vaginalis among HIV-1 seronegative partners in the TDF arm (6% versus 8% for placebo, p<0.01) and for the FTC/TDF arm (6% versus 8% for placebo, p<0.05), the prevalence of HSV-2 among HIV-1 seronegative partners in the FTC/TDF arm (54% versus 58% for placebo, p<0.05), and the proportion of HIV-1 seropositive female participants who were pregnant in the TDF arm (15% versus 12%, p<0.05).
N/A not available/not applicable