BACKGROUND: Current guidelines in the majority of developing countries use a viral load (VL) cutoff of 1000 copies/mL to define virologic failure (VF). However, research increasingly demonstrates that VL from 50-999 copies/mL or “low-level viremia” (LLV) is a risk factor for future VF.
METHODS: A retrospective chart review was performed using the health records from the Baylor College of Medicine Children’s Foundation - Tanzania sites in Mbeya and Mwanza. CALHIV up to the age of 19 years who had been on antiretroviral therapy (ART) for =6 months (by July 2021) were included in the analysis. Participants were followed longitudinally for at least two subsequent VLs after an initial undetectable VL (<50 copies/mL). VF was defined as =1000 copies/mL.
RESULTS: A total of 670 CALHIV were included in the outcome analysis. LLV occurred in 47.5%(318/670) and of those, 52.5%(167/318) had VL 50-199 copies/mL, 27.4%(87/318) had 200-399 copies/mL, and 20.1%(64/318) had 400-999 copies/mL. The Kaplan-Meier plot (figure) shows higher risk of failure with higher LLV category (p<0.0001). When looking at predictors of VF, a Cox proportional hazard model showed that there was an increased risk of VF with higher LLV when compared to <50 copies/mL: adjusted hazard ratio (AHR) 1.73 with 50-199 copies/mL (95%CI: 1.14-2.62, p=0.01), AHR 2.19 with 200-399 copies/mL (95%CI: 1.36-3.51, p=0.001), and AHR 3.34 with 400-999 copies/mL (95%CI: 2.09-5.36, p<0.0001). On multivariable analysis, age of 10-14 years (p=0.03) and immunosuppression, moderate (p=0.008) or severe (p=0.009), were associated with VF.


CONCLUSIONS: LLV was associated with increased risk of VF with higher levels LLV corresponding to higher risk. Age 10-14 years and immunosuppression were also associated with increased risk of VF.

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