Predictors of virological failure among people living with HIV switching from an effective first-line antiretroviral regimen

Objectives: Aim of this study was to assess the predictors of virological failure (VF) among patients living with HIV (PLWHIV) switching from an effective first-line antiretroviral therapy (ART) regimen, and to evaluate the emergence of resistance-associated mutations (RAMs). Methods: All adult patients enrolled in the ARCA cohort who started ART after 2010, with at least 6 months of virological suppression (VS) before ART switch and with an available genotypic resistance test (GRT) at baseline were included. Results: Thirty-two patients out of the 607 PLWHIV included (5.3%) experienced VF after a median of 11 months from ART switch. Younger age (aHR 0.96, 95%CI 0.92- 0.99, p=0.023), being male who have sex with male (aHR 0.15, 95%CI 0.03-0.69, p=0.014) and longer time from VS to ART switch (aHR 0.97, 95%CI 0.95-1.00, p= 0.021) resulted protective towards VF, while receiving a first-line regimen containing a backbone other than ABC/3TC or TXF/FTC (aHR 3.61, 95%CI 1.00-13.1, p=0.050) and a boosted protease inhibitor (bPI) as anchor drug (aHR 3.34, 95%CI 1.20-9.28, p=0.021) were associated with higher risk of VF. GRT at the moment of VF was available only for 13 patients (40.6%). Conclusions: ART switch in patients with stable control of HIV infection is a safe practice, even if particular attention should be paid in certain cases of patients switching from regimens containing low-performance backbones or PIs.