Efficacy and safety of boosted and unboosted atazanavir-containing antiretroviral regimens in real life: results from a multicentre cohort study

BACKGROUND: Atazanavir (ATV) has demonstrated high efficacy and safety in both
treatment-naïve and treatment-experienced patients. Some comparative data are
available on the durability of ritonavir-boosted (ATV/r) and unboosted
formulations, but there are no data on clinicians' motivations for choosing one
or another in everyday practice. The aim of this study was to evaluate the
long-term efficacy of boosted and unboosted ATV in a cohort of
treatment-experienced patients.
METHODS: All patients included in the study were enrolled in an observational
cohort within the Surveillance Cohort Long-Term Toxicity Antiretrovirals (SCOLTA)
Project. Data on CD4 cell count, HIV viral load, metabolic parameters and adverse
events of grade 3-4 are collected through an on-line system every six months. The
duration of treatment with ATV was evaluated using the Kaplan-Meier curve and
boosted and unboosted regimens were compared using the log-rank test.
RESULTS: A total of 509 patients starting ATV as a component of their
antiretroviral therapy were enrolled in the SCOLTA Project at the time of the
study. Boosted ATV was received by 379 patients (74.5%) while 130 (25.5%) were
treated with the unboosted formulation. The last therapeutic regimen did not
influence the choice of ATV formulation. The mean observational time was 23.9
months. At the end of follow-up, 58.5% of patients on unboosted ATV and 58.1% of
patients on ATV/r continued the treatment and no statistically significant
differences were observed for ATV durability between the formulations or among
the single causes of therapy interruption.
CONCLUSIONS: Our results suggest that, in unselected clinical settings,
ATV-containing antiretroviral therapy is durable and safe in both its
formulations.