Evaluating the Effect of Early vs. Late ARV Regimen Change After Failing on an Initial Regimen: Results from the AIDS Clinical Trials Group Study A5095

• Activity Number: 350
• Type: Contributed
• Date/Time: Tuesday, August 3, 2010 : 10:30 AM to 12:20 PM
• Sponsor: Health Policy Statistics Section
• Author(s): Li Li*+ and Brent Johnson and Joseph Eron and Heather Ribaudo and Roy Gulick
• Companies: Emory University and Emory University and The University of North Carolina at Chapel Hill and Harvard University and Cornell University
• Keywords: Double robustness ; Semi-parametric efficient estimation ; Missing data ; Causal inference

Abstract

In some clinical trials, such as the AIDS Clinical Trials Group Study (ACTG) A5095, patients randomized to initial antiretroviral treatment, who fail to suppress HIV RNA or have a rebound of HIV RNA on therapy, are allowed to switch to another ARV regimen based on clinician and patient decisions. However, the optimal timing of switching ARV therapy to ensure sustain virologic suppression is not known. We delineate a statistical framework to estimate the effect of early versus late regimen change using data from ACTG A5095 in a context of two-stage designs. The estimators we propose are doubly-robust and locally efficient. We found that for patients on an efavirenz-contained ARV therapy, regimen changes made within 8 weeks of confirmed virologic failure on initial regimen were associated with lower cumulative HIV RNA level, higher cumulative CD4 cell counts, and spent a larger proportion.