Incidence and predictors of virological failure among HIV infected children and adolescents receiving second-line antiretroviral therapy in Uganda, a retrospective study.

Background: In Uganda, 20% (19,073/94,579) of children and adolescents (0-19 years) living with HIV (CALHIV) were receiving second-line antiretroviral therapy (ART) by the end of March 2020. Data on incidence and predictors of virological failure among these CALHIV on second-line ART is limited. Lack of this information and limited access to HIV drug resistance testing prevents early identification of CALHIV at risk of virological failure on second-line ART. The aim of this study was to determine the incidence and predictors of virological failure among CALHIV on second-line ART in Uganda.

Methodology: This was a retrospective cohort study of all CALHIV aged 0-19 years who were switched to second-line ART regimen between June 2010 and June 2019 at the Baylor Uganda Centre of Excellence clinic. Data was analysed using STATA 14. Cumulative incidence curves were used to assess incidence of virological failure. Factors associated with virological failure were identified using sub-distributional hazard regression analysis for competing risks considering death, transfer out and loss to follow-up as competing risks.

Results: Of 1104 CALHIV, 53% were male. At switch to Protease Inhibitor (PI) based second-line ART, majority (47.7%) were aged 5 - 9 years,56.2% had no/mild immune suppression for age while 77% had viral load copies < 100,000 copies/mL. The incidence of virological failure on second-line ART regimen among CALHIV was 3.9 per 100 person-years (PY) with a 10-year cumulative incidence rate of 32%. Factors significantly associated with virological failure were age 10 - 19 years (HR 3.2, 95% 1.6 - 6.2, p < 0.01) and HIV viral load count > 100,000 copies/mL (HR 2.2, 95% CI 1.5 - 3.1), p < 0.01) prior to second-line ART switch.

Conclusion: Treatment outcomes for children and adolescents on second-line ART are favourable with one third of them developing virological failure at 10 years of follow up. Adolescent age group and high HIV viral load at the start of second-line ART were significantly associated with virological failure on second-line ART. There is need to determine optimal strategies to improve ART treatment outcomes among adolescents with high viral load counts at second-line ART switch.