Background and importance Real-world studies on the effectiveness, durability and safety of two-drug regimens (2-DR) compared to three-drug regimens (3-DR) are needed to confirm clinical trial results and support their use in clinical practice.

Aim and objectives To assess the virological effectiveness of a 2-DR with dolutegravir/lamivudine (DTG/3TC) versus a 3-DR with tenofovir alafenamide/emtricitabine/bictegravir (TAF/FTC/BIC) and to compare the durability and safety of both regimens in an intention-to-treat analysis at 24 weeks in a real-life cohort of HIV-1 treatment-naïve (TN) and treatment-experienced (TE) patients.

Material and methods This was an observational, ambispective study that included all TN and TE patients who started 2-DR or 3-DR between 1 July 2018, and 30 September 2021. The primary endpoint was the percentage of patients with viral load (VL)≥50, at 24 weeks, of 2-DR versus 3-DR in TN and VL <50 copies/mL in TE. Rate of patients that continued with treatment and number of adverse events (AE) were also measured. Statistical analyses were performed with Stata 15.0.

Results 239 patients were included (27 TN and 212 TE). In TN group, 74% were on 2-DR and 55% were on 2-DR in TE group. In TN, logVL at study treatment initiation was 4.6 (4.1–5.1) in 2-DR and 5.4 (3.9–6) in 3-DR. Percentage of TE with VL<50 copies/mL at study treatment initiation was 84.6% in 2-DR and 73.7% in 3-DR. Five (20%) TN on 2-DR had VL≥50 copies/mL at week 24 versus two (29%) patients in 3-DR group, (difference: –8.8%; 95% CI –57.3 to 39.8%, p=0.71). In TE patients on 2-DR, 85.5% achieved VL<50 copies/mL at week 24 versus 87.5% in 3-DR group (difference: –2%; 95% CI –13.5 to 9.5%, p=0.74). At week 24, 95% of 2-DR patients continued with treatment versus 85.7% in 3-DR. In TE, 93.8% of 2-DR were on treatment versus 91.2% 3-DR patients. Eight TN in the 2-DR group (40%) reported any AE and two (28.6%) in the 3-DR group (p=0.68). In the TE group, 23 patients (19.7%) on 2-DR had an AE compared to 25 patients (26.3%) in 3-DR group (p=0.25).

Conclusion and relevance This study shows a similar effectiveness profile of DTG/3TC compared to TAF/FTC/BIC at 24 weeks. Additionally, durability and safety of 2-DR were confirmed to be similar to 3-DR.

Conflict of interest No conflict of interest