Comparative risk of failure of ABC/3TC or TDF/FTC based first-line regimens in patients with a high viral load

To compare the efficacy, in current clinical practice, of first regimens containing abacavir with lamivudine (ABC/3TC) or tenofovir with emtricitabine (TDF/FTC) in patients with baseline viral load ≥100,000 HIV-1 RNA copies/mL.

Using a prospective cohort, we selected all patients starting a first HIV regimen based either on ABC/3TC or on TDF/FTC. The propensity score (PS) method was used to limit the indication bias due to the observational nature of the data. Adjusting and weighting methods via PS were used to compare the effectiveness of a first regimen containing ABC/3TC or TDF/FTC. The primary outcome was treatment failure by month 12 (M12).

Overall, 2781 patients started an antiretroviral (ARV) regimen with ABC/3TC or TDF/FTC each in combination with efavirenz, boosted atazanavir or boosted darunavir. Among the 2472 uncensored patients before M12, 962 (39%) had a baseline viral load ≥100,000 copies/mL of whom 294 were in treatment failure at or before M12. Our analyses showed no difference between ABC/3TC and TDF/FTC in the risk of treatment failure at M12 in patients starting an ARV regimen with a high viral load (≥100,000 copies/mL).

Using a large prospectively collected cohort of patients seeking care in France, we found no evidence that ABC/3TC based regimens led to more failures than TDF/FTC based ones in patients with high baseline viral loads.