Predictors of residual viraemia in patients on long-term suppressive antiretroviral therapy

Abstract

Background: HIV-1-infected individuals with plasma RNA<50 copies/ml on antiretroviral therapy (ART) may have residual, low-level viraemia detectable by PCR assays that are able to detect a single copy of viral RNA (single-copy assay [SCA]). The clinical predictors of residual viraemia in patients on long-term suppressive ART are not yet fully understood.

Methods: We evaluated factors associated with residual viraemia in patients on suppressive ART who underwent screening for a raltegravir intensification trial (ACTG A5244). The screened population was HIV-1-infected adults receiving ART for ≥ 12 months with pre-ART HIV-1 RNA>100,000 copies/ml and on-therapy RNA levels below detection limits of commercial assays for ≥ 6 months.

Results: Of 103 patients eligible for analysis, the median age was 46 years and the median duration of viral suppression was 4.8 years. 62% had detectable viraemia (>0.2 copies/ml) by SCA (median 0.2 copies/ml, IQR <0.2-1.8). Younger patients had lower HIV-1 RNA levels than older individuals (r=0.27, P=0.005). Patients with virological suppression on ART for 2 years or less had higher residual viraemia than those with suppression for >2 years (median 2.3 versus 0.2 copies/ml; P=0.016).

Conclusions: Among HIV-1-infected patients with pre-ART HIV-1 RNA>100,000 copies/ml, residual viraemia was detectable in the majority (62%) despite many years of suppressive ART. Higher level viraemia was associated with older age and <2 years of virological suppression on ART. These findings should help in the selection of candidates for clinical trials of interventions designed to eliminate residual viraemia.

Figure 1

Frequency of screening HIV-1 RNA by single-copy assay

Figure 2. Baseline predictors of HIV-1 RNA by single-copy assay (SCA)

(A) Age (≤ 46, > 46 years) versus HIV-1 RNA by SCA (median age of the study population for this analysis was 46 years). (B) Years (≤ 2 vs. >2) since first HIV-1 RNA below detectable limits by commercial assays versus HIV-1 RNA by SCA. When the SCA measurement was below the detection limit, a value of 1/2 of the detection limit was imputed. The solid horizontal line indicates the median SCA value; the dashed lines indicate 25^th and 75^th percentile. (The 25^th percentile was 0.1 copies/mL for the group with age ≤46 years old and the group with >2 years since first HIV-1 RNA below detectable limits by commercial assays).