Table 2:
Pharmacokinetic results by ART category and implant type
| Unadjusted1 | Adjusted2 | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| ART category | # women (samples) | Pre-ART GM hormone concentrations (pg/mL) 3 | Post-ART GM hormone concentrations (pg/mL) 3 | Observed Pre-ART: Post-ART GMR4 | Predicted ART: No ART GMR5 (90% CI) | p-value | Predicted ART: No ART GMR5 (90% CI) | p-value | |
| Levonorgestrel | ART-naïve | 14 (85) | 441.95 | 402.40 | 0.91 | Ref | -- | Ref | -- |
| EFV | 8 (33) | 333.40 | 89.91 | 0.27 | 0.33 (0.27, 0.41) | <0.001 | 0.39 (0.31, 0.49) | <0.001 | |
| NVP | 6 (36) | 460.01 | 330.23 | 0.72 | 0.84 (0.67, 1.04) | 0.17 | 0.93 (0.74. 1,18) | 0.64 | |
| Etonogestrel | ART-naïve | 22 (140) | 255.74 | 204.79 | 0.80 | Ref | -- | Ref | -- |
| EFV | 3 (16) | 218.38 | 132.91 | 0.61 | 0.57 (0.38, 0.84) | 0.02 | 0.51 (0.34, 0.76) | 0.006 | |
| NVP | 7 (36) | 305.05 | 218.82 | 0.72 | 0.88 (0.67, 1.15) | 0.42 | 1.07 (0.77, 1.50) | 0.73 | |
ART=antiretroviral therapy; GM=geometric mean; GMR=geometric mean ratio; EFV=efavirenz; NVP=nevirapine
Adjusted only for days from ART initiation
Adjusted for days from ART initiation, age, BMI, nationality, and closest viral load
The median time for each ART-naïve woman was used to split the observations into “pre-ART” and “post-ART” so as to facilitate intra-subject comparisons in this group
The observed GMR is intra-subject, calculated as the ratio between geometric means of observed pre- and post-ART initiation samples
The no ART (reference) category GMRs from models include all samples from ART-naïve women as well as pre-ART samples from those who initiated ART during study, in order to better estimate changes due to initiating ART while accounting for background change in concentrations over time. Thus, these models incorporate information from within women and well as between women.