Simplification of protease inhibitor-containing regimens with efavirenz, nevirapine or abacavir: Safety and efficacy outcomes

Objective: To describe the immunological and virological
outcome, and the factors associated to discontinuation in
patients switching to a regimen containing efavirenz
(EFV), nevirapine (NVP) or abacavir (ABC) after long-term
viral suppression under protease inhibitor-including
HAART.
Design: Observational study at three outpatient clinics
for HIV care in Italy.
Methods: Patients with HIV RNA <80 copies/ml and CD4
>200 cells/ml for at least 6 months on a protease
inhibitor-containing treatment who switched to NVP,
EFV or ABC were included in the study. End-points were
immunological failure, virological failure and discontinuation
due to toxicity. Survival analyses were performed
to find out any independent variables predictive of
reaching the end-points.
Results: 177 patients were enrolled; 85 started EFV, 54
NVP and 38 ABC as part of the simplification regimen.
16/159 patients experienced immunological failure: the
variables associated to CD4 count decrease were HIV RNA
set point value (HR 2.32 for each log10 copies more,
P=0.040) and intolerance/toxicity as reason for simplification
(HR 3.96, P=0.05). 13/151 subjects showed
virological failure; an AIDS diagnosis (HR 6.04, P=0.021)
and the use of NVP (HR 7.98, P=0.027) were associated
to a worse virological outcome, while patients naive
before HAART showed a lower risk of failure (HR 0.008,
P=0.007). 16/177 patients discontinued simplification
regimen due to toxicity; longer HAART duration before
switch was associated to risk reduction (HR 0.92,
P=0.004).
Conclusions: Simplification is safe and effective, but it
should be offered to patients with shorter treatment
duration, and in good clinical and immunovirological
conditions.