The VACS Index as a Surrogate Outcome for HIV/AIDS Clinical Trials

• Activity Number: 605
• Type: Topic Contributed
• Date/Time: Thursday, August 2, 2012 : 8:30 AM to 10:20 AM
• Sponsor: Section on Government Statistics
• Author(s): Katherine Kirkwood*+ and Tassos Kyriakides and Sheldon T. Brown and Amy C. Justice and Janet Tate
• Companies: VA Cooperative Studies Program and VA Cooperative Studies Program and James J. Peters VAMC and VA Connecticut Healthcare System, West Haven and VA Connecticut Healthcare System, West Haven
• Keywords: randomized trials ; mortality ; prognostic index ; biomarkers ; surrogate outcomes

Abstract

Reliable intermediate outcome measures are needed to assess clinical interventions in the current era of HIV treatment. We evaluated the performance of the Veterans Aging Cohort Study (VACS) Index that uses routine clinical biomarkers to predict mortality as a surrogate outcome for randomized clinical trials. VACS Index scores were determined from data collected in the Options In Management with Antiretrovirals (OPTIMA) multi-national study of treatment strategies in patients with advanced HIV. Proportional hazards regression and survival analysis using baseline VACS Index scores and changes in score during treatment were used to assess the utility of the index as an outcome for future clinical trials. Imputation of missing scores and/or score components will yield datasets to be used for additional sensitivity analyses. VACS Index scores at baseline correlated highly with mortality and with time to death in both newly-diagnosed and advanced HIV patients. The VACS Index accurately predicted mortality and responded to changes in treatment. Measuring changes in VACS Index scores may offer an efficient alternative endpoint for the design of RCTs among patients with HIV.