Incidence of low-level viremia and its impact on virologic failure among people living with HIV-1 who switched to elvitegravir-based antiretroviral therapy

Abstract

We aimed to investigate the incidence of low-level viremia (LLV) and its impact on virologic failure (VF) in people living with HIV (PLWH) on stable antiretroviral therapy (ART) who switched to co-formulated elvitegravir, cobicistat, emtricitabine and tenofovir alafenamide (EVG/c/FTC/TAF). PLWH aged 18 years or older who had received ART with plasma HIV RNA load (PVL) <50 copies/mL for 6 months or longer and switched to EVG/c/FTC/TAF between March and October 2018 were retrospectively included. The incidence of LLV (defined as PVL of 50-999 copies/mL) and VF (PVL ≥1000 copies/mL) was calculated and represented by Kaplan-Meier plots. The generalised estimating equation model was constructed to identify factors associated with LLV and VF. Resistance-associated mutations were determined using population sequencing. A total of 1078 PLWH were included. The incidence rates of LLV and VF after the switch to EVG/c/FTC/TAF were 3.5 and 0.8 events per 100 person-years of follow-up, respectively, whereas the respective cumulative incidence of LLV and VF reached 11.7% and 2.9% within 3 years of follow-up. LLV was associated with any LLV episode before or after the switch and prior exposure to integrase strand transfer inhibitor-based ART. VF was associated with any LLV before or after the switch and prior exposure to raltegravir, but not the level or frequency of LLV. The risks of LLV and VF were low in PLWH who had achieved virologic suppression and switched to EVG/c/FTC/TAF, and the presence of LLV and prior exposure to raltegravir increased the risk of VF.