Resistance profiles after different periods of exposure to a first-line antiretroviral regimen in a Cameroonian cohort of HIV type-1-1infected patients

Background: The lack of HIV type-1 (HIV-1) viral load (VL) monitoring in resource-limited settings might favour the accumulation of resistance mutations and thus hamper second-line treatment efficacy. We investigated the factors associated with resistance after the initiation of antiretroviral therapy (ART) in the absence of virological monitoring. Methods: Cross-sectional VL sampling of HIV-1-infected patients receiving first-line ART (nevirapine or efavirenz plus stavudine or zidovudine plus lamivudine) was carried out; those with a detectable VL were genotyped. Results: Of the 573 patients undergoing VL sampling, 84 were genotyped. The mean number of nucleoside/nucleotide reverse transcriptase inhibitor (NRTI) mutations increased with the duration of ART exposure (P=0.02). Multivariable analysis showed that patients with a CD4⁺ T-cell count ≤50 cells/mm³ at ART initiation (baseline) had a higher mean number of both NRTI and non-NRTI (NNRTI) mutations than those with a baseline CD4⁺ T-cell count >50 cells/mm³ (2.10 versus 0.56; P+ T-cell count ≤50 cells/mm³ predicted ≥1 NRTI mutation (adjusted odds ratio [AOR] 7.49, 95% confidence interval [Cl] 2.20-32.14), ≥1 NNRTI mutation (AOR 4.25, 95% Cl 1.36-15.48), ≥1 thymidine analogue mutation (AOR 8.45, 95% Cl 2.16-40.16) and resistance to didanosine (AOR 6.36, 95% Cl 1.49-32.29) and etravirine (AOR 4.72, 95% Cl 1.53-15.70). Conclusions: Without VL monitoring, the risk of drug resistance increases with the duration of ART and is associated with lower CD4⁺ T-cell counts at ART initiation. These data might help define strategies to preserve second-line treatment options in resource-limited settings.