Table 4.
Associations between any HIV risk and high PrEP adherence in the HPTN 082 cohort, as indicated by TFV-DP and TFV
| DBS TFV-DP (N=371) | Plasma TFV (N=413) | |||||
|---|---|---|---|---|---|---|
| Primary outcome: High PrEP Adherence | ||||||
| Visits with TFV-DP 700fmol/punch (N=197/1081 visits)1,2 | aRR (95% CI)4 | p-value | Visits with TFV ≥40 ng/mL (N=389/1114 visits)1,3 | aRR (95% CI)4 | p-value | |
| No HIV risk | 55 (13.8) | REF | --- | 120 (29.1) | REF | --- |
| Any HIV risk | 142 (20.8) | 1.57 (1.09-2.25) | 0.014 | 269 (38.4) | 1.36 (1.11-1.65) | 0.0025 |
| Secondary outcome: Any PrEP Use | ||||||
| Visits with quantifiable TFV-DP (N=623/1081 visits)1,5 | aRR (95% CI)2 | p-value | Visits with quantifiable TFV (N=512/1114 visits)1,6 | aRR (95% CI)2 | p-value | |
| No HIV risk | 213 (53.5) | REF | --- | 166 (40.2) | REF | --- |
| Any HIV risk | 410 (60.0) | 1.15 (1.03-1.29) | 0.013 | 346 (49.4) | 1.27 (1.09-1.49) | 0.0022 |
DBS=dried blood spot; TFV-DP=tenofovir diphosphate; TFV=tenofovir; PrEP=pre-exposure prophylaxis; aRR=adjusted relative risk; 95% CI=95% confidence interval
Data are presented as frequency (percentage)
700 fmol/punch represents consistent dosing (≥4 PrEP doses per week) and was associated with 100% PrEP effectiveness among men who have sex with men.
40 ng/mL represents consistent stead-state dosing (≥4 PrEP doses per week) and was highly predictive of PrEP efficacy among African women and men in the Partners PrEP Study.
Multivariable models adjusted for study site and randomized arm
The limit of detection for TFV-DP was 15.6 fmol/punch
The limit of detection for plasma TFV was 0.15 ng/mL