Table 2.
Association Between Resistance and Drug Concentrations on First-line Antiretroviral Therapy (ART) in Samples Taken Prior to Switching to Second-line ART
| Resistance Mutations | All | Therapeutic Drug Concentrations on First-line ARTa | Subtherapeutic Drug Concentrations on First-line ARTb | |
|---|---|---|---|---|
| (n = 73) | (n = 34) | (n = 39) | P Valuec | |
| No major DRM | 21 (28.8) | 1 (2.9) | 20 (51.3) | <.01 |
| Single-class resistance | 10 (13.7) | 1 (2.9) | 9 (23.1) | .02 |
| Two-class resistance | 42 (57.5) | 32 (94.1) | 10 (25.6) | <.01 |
| ≥1 NNRTI mutations | 49 (67.1) | 32 (94.1) | 17 (43.6) | <.01 |
| ≥1 NRTI mutations | 45 (61.6) | 33 (97.1) | 12 (30.8) | <.01 |
| ≥1 NRTI mutations (excluding M184V/I) | 26 (35.6) | 18 (52.9) | 8 (20.5) | .01 |
| M184V/I | 42 (57.5) | 32 (94.1) | 10 (25.6) | <.01 |
| TAM | ||||
| 0 | 50 (68.5) | 18 (52.9) | 32 (82.0) | .01 |
| ≥1 | 23 (31.5) | 16 (47.1) | 7 (17.9) | |
| K65R | 3 (4.1) | 2 (5.9) | 1 (2.6) | .6 |
| Q151M | 3 (4.1) | 3 (8.8) | 0 (0.0) | .1 |
| NRTI cross-resistance DRM | 14 (19.2) | 9 (26.5) | 5 (12.8) | .23 |
Data are presented as No. (%).
Abbreviations: ART, antiretroviral therapy; DRM, drug resistance mutation; NNRTI nonnucleoside reverse transcriptase inhibitor; NRTI, nucleoside reverse transcriptase inhibitor; TAM, thymidine analogue mutation.
a Therapeutic first-line ART: NNRTI concentration equal to or greater than Ctrough and lamivudine detected.
b Subtherapeutic first-line ART: NNRTI concentration below Ctrough and/or lamivudine below limit of quantification for the assay.
c Fisher exact test.