Initiation of Dolutegravir Versus Efavirenz on Viral Suppression and Retention at 6 months: A Regression Discontinuity Design.

Background: In 2019, South Africa's Antiretroviral Therapy (ART) Treatment Guidelines replaced efavirenz with dolutegravir in first-line ART.

Setting: We assessed the impact of this national guideline change on retention and viral suppression in the Themba Lethu Clinical Cohort, Johannesburg, South Africa. We applied a regression discontinuity design in a prospective cohort study of 1654 adults living with HIV initiating first-line ART within 12 months (±12 months) of the guideline change.

Methods: We compared outcomes in individuals presenting just before and after the guideline change and estimated intention-to-treat effects on initiating a dolutegravir- vs efavirenz-based regimen. Primary outcomes were retention and viral suppression. Participants were defined as retained in care if a visit took place within ±3 months of the 6-month end point. Viral suppression was defined as having a viral load ≤1000 copies/mL 3 months before and up to 6 months after the 6-month end point.

Results: The 2019 guideline change led to an increase in uptake of dolutegravir. We noted a 26.6 percentage point increase in the proportion initiating dolutegravir [95% Confidence Interval (CI): 14.1 to 38.6]. We saw a small increase in viral suppression [Risk Difference (RD): 7.4 percentage points; 95% CI: -1.6 to 16.5] and no change in retention (RD: -1.7 percentage points; 95% CI: -13.9 to 10.5) at 6 months, though our findings were imprecise.

Conclusions: Our estimates suggest early uptake of the revised treatment guidelines after implementation. Despite this, there was no meaningful change in viral suppression and retention rates at 6 months.