Table 2.
Adherence to Study Products.*
| Measure of Adherence | Total (N = 5007) |
Oral TDF (N = 1002) |
Oral TDF-FTC (N = 994) |
Oral Placebo (N = 1008) |
TFV Gel (N = 1003) |
Placebo Gel (N = 1000) |
|---|---|---|---|---|---|---|
| Mean rate of adherence (%) | ||||||
| Assessed by clinic-based product count† | 86 | 84 | 88 | 90 | 83 | 84 |
| Assessed by face-to-face interview‡ | 90 | 91 | 90 | 91 | 90 | 90 |
| Assessed by ACASI§ | 88 | 87 | 87 | 88 | 88 | 89 |
| Mean proportion of quarterly plasma samples with TFV detected (%)¶ | NA | 30 | 29 | NA | 25 | NA |
| Proportion of women with TFV not detected in any quarterly plasma samples (%)¶ | NA | 58 | 50 | NA | 57 | NA |
| Mean proportion of vaginal swab samples with TFV detected (%)‖ | NA | NA | NA | NA | 49 | NA |
| Proportion of women with TFV not detected in any vaginal swab samples (%)‖ | NA | NA | NA | NA | 41 | NA |
ACASI denotes audio computer-assisted self-interview, and NA not applicable.
Participants were asked to return empty pill bottles, unused pills, and unused vaginal gel applicators at each monthly visit. Percentages are the estimated mean proportions of doses not returned and presumed to have been used. The mean proportion in the Total column is based on 4994 participants with follow-up data.
In the interviews, women were asked to report the number of doses of study product they used in the previous week, and these were summed across monthly follow-up visits. The mean proportion in the Total column is based on 4935 participants.
In the ACASI, women were asked to report the number of doses of study product they used in the previous week, and these were summed across quarterly follow-up visits. The mean proportion in the Total column is based on 4739 participants.
Proportions were calculated among the 488 participants in the random cohort of the case–cohort subset who had quarterly plasma samples available (158 in the TDF group, 157 in the TDF-FTC group, and 173 in the TFV gel group); the median number of quarterly samples tested per participant was 3 (range, 1 to 10).
Proportions were calculated among the 170 participants randomly assigned to the TFV gel group who were in the random cohort of the case–cohort subset and provided at least one vaginal swab sample (with samples collected at 6-month intervals). A total of 255 swabs were collected from these participants between the month 5 and month 17 visits and were available for analysis; 85 participants had two swabs tested, and 85 had one swab tested.