Switches from lopinavir/ritonavir (LPV/r) to either atazanavir/ritonavir (ATV/r) or unboosted ATV (ATV) are increasingly common in clinical practice, but data on outcome comparison between these two simplification strategies are very limited.
Methods: Multicenter, observational, retrospective study. Data were collected from five Italian clinics. The objective of the study was to investigate the outcome of LPV/r simplification with ATV/r or ATV and to identify factors predicting virological rebound. Patients who switched from LPV/r to ATV/r or ATV with an HIV-RNA value<50 copies/mL at the time of switch and with at least one follow-up visit were included. We evaluated 468 patients (74.1% males), followed for a median (Q1-Q3) of 547 (305-788) days: 380 (81%) and 88 (19%) switched to ATV/r and to ATV, respectively. Virological rebound was detected in 78/468 (16.7%, 95% CI: 13.6 -20.3) patients [16/88 (18.2%, 95% CI: 11.4 -27.6) switched to ATV and 62/380 (16.3%, 95% CI: 12.9 -20.4) to ATV/r (p=0.638)]. Virological rebound was more frequent in patients who started LPV/r with HIV-RNA >30000 copies/mL (28% vs 6%, p=0.014). Replacing lopinavir/r with ATV or ATV/r yielded similar rates of virological rebound. Viral load at the initiation of lopinavir/r may be useful in driving the choice between ATV/r and ATV.