Association between changes in script renewal periods and HIV viral non-suppression: a cohort study of a South African private-sector HIV program.

Introduction Evidence is needed to inform differentiated service delivery models for people with HIV (PWH). During the COVID-19 pandemic, South Africa temporarily changed the validity of repeat prescriptions for ART from 6 to 12 months. We evaluated the association between these changes and HIV viral non-suppression in the private health sector. Methods We analysed routine claims data from a large private-sector HIV management programme. PWH aged >15 years from 4 months after first ART evidence were included. We conducted an interrupted time-series analysis comparing trends in the proportions of PWH with viral non-suppression (viral load ≥50 copies/mL) during three periods: January 1, 2019 to April 23, 2020 (conventional 6-monthly script renewal); April 24, 2020 to September 25, 2021 (12-monthly renewal); and September 26, 2021 to November 30, 2022 (6-monthly renewal re-instated). We used weighting to maintain the age, sex, ART regimen and medical scheme distributions of our study population over time. Results Monthly odds of viral non-suppression initially decreased by 4% per annum (adjusted odds ratio (aOR) 0.96, 95% confidence interval (CI) 0.93-0.99). During 12-monthly renewal, there were steeper declines of 11% per annum (aOR 0.89, 95% CI 0.87-0.91). After 6-monthly renewal was re-introduced, viral non-suppression instead increased by 6% per annum (aOR 1.06 95% CI 1.03-1.09). Changes in slopes were significant (p-values <0.001). Conclusion Measures implemented during COVID-19 to ensure continued access to chronic medication provided unique evidence for models involving less frequent clinical visits. Extending prescription renewal periods was not associated with worse virologic outcomes among privately-insured PWH.