Attrition Rates in HIV Viral Load Monitoring and Factors Associated With Overdue Testing Among Children Within South Africa's Antiretroviral Treatment Program: Retrospective Descriptive Analysis

Background: Numerous studies in South Africa have reported low HIV viral load (VL) suppression and high attrition rateswithin the pediatric HIV treatment program. Objective: Using routine laboratory data, we evaluated HIV VL monitoring, including mobility and overdue VL (OVL) testing,within 5 priority districts in South Africa. Methods: We performed a retrospective descriptive analysis of National Health Laboratory Service (NHLS) data for childrenand adolescents aged 1-15 years having undergone HIV VL testing between May 1, 2019, and April 30, 2020, from 152 facilitieswithin the City of Johannesburg, City of Tshwane, eThekwini, uMgungundlovu, and Zululand. HIV VL test-level data werededuplicated to patient-level data using the NHLS CDW (Corporate Data Warehouse) probabilistic record-linking algorithm andthen further manually deduplicated. An OVL was defined as no subsequent VL determined within 18 months of the last test.Variables associated with the last VL test, including age, sex, VL findings, district type, and facility type, are described. Amultivariate logistic regression analysis was performed to identify variables associated with an OVL test. Results: Among 21,338 children and adolescents aged 1-15 years who had an HIV VL test, 72.70% (n=15,512) had a follow-upVL test within 18 months. Furthermore, 13.33% (n=2194) of them were followed up at a different facility, of whom 3.79%(n=624) were in a different district and 1.71% (n=281) were in a different province. Among patients with a VL of >= 1000 RNAcopies/mL of plasma, the median time to subsequent testing was 6 (IQR 4-10) months. The younger the age of the patient, thegreater the proportion with an OVL, ranging from a peak of 52% among 1-year-olds to a trough of 21% among 14-year-olds. Onmultivariate analysis, 2 consecutive HIV VL findings of >= 1000 RNA copies/mL of plasma were associated with an increasedadjusted odds ratio (AOR) of having an OVL (AOR 2.07, 95% CI 1.71-2.51). Conversely, patients examined at a hospital (AOR0.86, 95% CI 0.77-0.96), those with >= 2 previous tests (AOR 0.78, 95% CI 0.70-0.86), those examined in a rural district (AOR0.63, 95% CI 0.54-0.73), and older age groups of 5-9 years (AOR 0.56, 95% CI 0.47-0.65) and 10-14 years (AOR 0.51, 95% CI0.44-0.59) compared to 1-4 years were associated with a significantly decreased odds of having an OVL test.Conclusions: Considerable attrition occurs within South Africa's pediatric HIV treatment program, with over one-fourth ofchildren having an OVL test 18 months subsequent to their previous test. In particular, younger children and those with virological failure were found to be at increased risk of having an OVL test. Improved HIV VL monitoring is essential for improving outcomeswithin South Africa's pediatric antiretroviral treatment program