Table 2.
Genotypic susceptibility scores for antiretroviral drug regimens used in South African public health sector.
| Genotypic Susceptibility Score for Regimen | ||||
|---|---|---|---|---|
| Current Regimen * | N = 2934 | <2 | 2 | >2 |
| TDF-based | n = 649 | |||
| TDF + XTC + EFV | 20 | 17 (85%) | 0 | 3 (15%) |
| TDF + XTC + boosted ATV/LPV | 574 | 255 (44.42%) | 111 (19.34%) | 208 (36.24%) |
| TDF + XTC + boosted DRV | 19 | 12 (63.16%) | 4 (21.05%) | 3 (15.79%) |
| TDF + XTC + RAL | 4 | 3 (75%) | 0 | 1 (25%) |
| TDF + XTC + DTG | 19 | 8 (42.10%) | 2 (10.53%) | 9 (47.37%) |
| TDF + XTC + RAL + boosted DRV | 6 | 3 (50%) | 0 | 3 (50%) |
| TDF + XTC + DTG + boosted DRV | 6 | 1 (16.67%) | 2 (33.33%) | 3 (50%) |
| TDF + XTC + DTG + boosted DRV + ETR | 1 | 0 | 0 | 1 (100%) |
| AZT-based | n = 1927 | |||
| AZT + XTC + boosted ATV/LPV | 1911 | 761 (39.82%) | 663 (34.69%) | 487 (25.49%) |
| AZT + XTC + boosted DRV | 4 | 0 | 1 (25%) | 3 (75%) |
| AZT + XTC + DTG | 10 | 4 (40%) | 2 (20%) | 4 (40%) |
| AZT + XTC + DTG + boosted DRV | 1 | 0 | 0 | 1 (100%) |
| AZT + XTC + DTG + boosted DRV + ETR | 1 | 0 | 0 | 1 (100%) |
| TDF- and AZT-based | n = 45 | |||
| AZT + XTC + boosted ATV/LPV + TDF | 37 | 4 (10.81%) | 3 (8.11%) | 30 (81.08%) |
| AZT + XTC + boosted DRV + TDF | 6 | 0 | 0 | 6 (100%) |
| AZT + XTC + DTG + TDF | 1 | 0 | 0 | 1 (100%) |
| AZT + XTC + DTG + boosted DRV + TDF | 1 | 0 | 0 | 1 (100%) |
| ABC-based | n = 313 | |||
| ABC + XTC + boosted ATV/LPV | 307 | 199 (64.82%) | 3 (0.98%) | 105 (34.20%) |
| ABC + XTC + DTG | 6 | 4 (66.67%) | 0 | 2 (33.33%) |
ABC, abacavir; ATV, atazanavir; AZT, zidovudine; DRV, darunavir; DTG, dolutegravir; EFV, efavirenz; ETR, etravirine; LPV, lopinavir; RAL, raltegravir; TDF, tenofovir disoproxil fumarate; XTC, lamivudine/emtricitabine. * Genotypic tests were conducted at the time of antiretroviral treatment failure. Integrase strand transfer inhibitors are assumed to have an individual genotypic susceptibility score (GSS) of 1 if HIV-1 integrase testing was not already included in the genotypic resistance test record. Boosted refers to ritonavir-boosted regimens. For ATV/LPV, the drug with the lower penalty score in Stanford University HIV Drug Resistance Database was used.