Durability of FTC/TDF‐containing cART regimens in a large cohort of HIV‐infected patients seen for care in Italy

Atripla is a fixed‐dose drug combining FTC/TDF/EFV into a single pill and may increase adherence. To our knowledge, there is little data comparing the durability of Atripla vs. other regimens. Our first aim was to compare the durability of Truvada (TVD)/EFV or TVD/PIr or Atripla started when ART‐naïve, in terms of time to virological failure (VF first of 2 consecutive values>50 and>200 copies/mL), time to discontinuation of any drug in the regimens, or both. Then, we aimed to compare the incidence of virological rebound (VR)>200 copies/mL in patients (pts) currently receiving these same regimens after achieving a viral load (VL)≤80 copies/mL. Pts in the Icona Foundation Study who started for the first time a cART regimen with TVD/EFV or TVD/PIr or Atripla, either while ART‐naïve (analysis 1) or while with a VL≤80 (analysis 2) were included. In analysis 1, pts' follow‐up accrued from cART initiation to the date of the event (VF or discontinuation of any drug in the regimen) or to the date of last available visit/VL. In the TVD/EFV group a switch to Atripla was not counted as an event. Survival analysis employing KM curves and Cox regression model was used. In analysis 2, follow‐up accrued from the date of first VL≤80 (which could be achieved with any cART) to VR or last VL and only person years (PY) on the regimens of interest were considered. Rates were calculated as number of VR per 1000 PY and relative rates (RR) compared using a Poisson regression model. In analysis 1, 515 pts starting TVD/EFV, 1001 TVD/PIr and 160 Atripla when ART‐naïve on average in 2010 (IQR: 2008–2011) were included. PI/r were LPV (33%), ATV (38%) fos‐APV (4%) and DRV (24%). Median age was 38 years, 19% females, 40% heterosexuals. Pts starting Atripla were younger, less likely to be female, IDU, HCV co‐infected, to have AIDS and they had higher CD4 count (334 vs. 280). By 2 years, 48% (95% CI: 43–53) of those initiating TVD/PIr experienced the composite endpoint of VF or drug discontinuation vs. 20% in the other groups (p=0.0001). Median time to switch from TVD to Atripla in the EFV group was 17 months (95% CI: 12–23). The table shows the results of the Cox regression analysis. In analysis 2 (n=1,425), the rates of VR were 16.8 per 1000 PY for TVD/PIr, 11.17 for TVD/EFV and 5.3 for Atripla (adjusted RR vs. TVD/PIr=0.51, 95% CI: 0.19–1.34). Durability of Atripla was comparable to that of TVD/EFV and potentially longer than that of TVD/PIr. Unmeasured confounding cannot be ruled out.Crude and adjusted relative hazards from fitting a Cox regression Outcomes No. with event (%) Crude RH (95% CI) p‐value Adjusted* RH (95% CI) p‐valueVL>50 copies/mLTruvada+PI/r 131 (13%) 1.00 1.00Truvada+EFV 54 (10%) 0.60 (0.43,0.83) 0.002 0.61 (0.42,0.89) 0.009 Atripla 8 (5%) 0.66 (0.32,1.37) 0.265 1.15 (0.54,2.48) 0.716Stop of any drugTruvada+PI/r 322 (32%) 1.00 1.00Truvada+EFV 79 (15%) 0.37 (0.29, 0.47) <.001 0.33 (0.25,0.44) <.001 Atripla 23 (14%) 0.50 (0.32,0.77) 0.002 0.50 (0.31,0.80) 0.004VL>200 copies / mL or stop of any drugTruvada+PI/r 314 (31%) 1.00 1.00Truvada+EFV 84 (16%) 0.39 (0.31,0.50) <.001 0.37 (0.28,0.49) <.001 Atripla 23 (14%) 0.52 (0.33,0.80) 0.003 0.57 (0.35,0.91) 0.017*adjusted for age, gender, nation of birth, mode of HIV tranmission, hepatitis co‐infection status, AIDS diagnosis, baseline CD4 count and viral load an year of starting cART and stratified by clinical centre