Patterns of Detectable Viral Load in a Cohort of HIV-positive Adolescents on Antiretroviral Therapy in South Africa

Introduction: Despite improved treatment and access to care, adolescent AIDS deaths are decreasing more slowly than in any other age group. There is lack of longitudinal data around adolescent adherence and the dynamics of viraemia over time. We aimed to describe patterns of detectable viral load (VL) in a cohort of adolescents attending an ARV clinic in Cape Town, South Africa.

Methods: We conducted a retrospective cohort study of all patients on antiretroviral therapy aged 10 to 19 years. Participants were included if they underwent at least two VL measurements and remained in care at the Groote Schuur Hospital HIV Clinic for at least 24 months between 2002 and 2016. The primary outcome was two consecutive HIV VL >100 copies/mL, in line with the lower limit of detection of assays in use over the follow-up period.

Results And Discussion: Of the 482 screened participants, 327 met inclusion criteria. Most participants had perinatally acquired HIV (n = 314; 96%), and 170 (52%) were males. Overall, there were 203 episodes of confirmed detectable VL involving 159 (49% (95% CI 43% to 54%)) participants during the follow-up period. Six participants had genotyped resistance to protease inhibitors. Four of these never suppressed, while two suppressed on salvage regimens. Total follow-up time was 1723 person years (PY), of which 880 (51%) were contributed by the 159 participants who experienced detectable VL. Overall time with detectable VL was 370 PY. This comprised 22% of total follow-up time, and 42% of the follow-up time contributed by those who experienced detectable VL. The rate of detectable VL was 11.8 (95% CI 10.3 to 13.5) episodes per 100 PY. The risk increased by 24% for each year of increasing age (Relative Risk 1.24 (95% CI 1.17 to 1.31); p < 0.0001). There was no sex difference with respect to duration (p = 0.4), prevalence (p = 0.46) and rate (p = 0.608) of detectable VL.

Conclusions: Clinicians need to be alert to the high prevalence of detectable VL during adolescence so as to pre-empt it and act swiftly once it is diagnosed. This study helps to highlight the risk of detectable VL that is associated with increase in age as well the high proportion of time that poorly adherent adolescents spend in this state.