Assessing Placebo Response in Chronic Pain Trials by Latent Subgroup Analysis Models

• Activity Number: 305
• Type: Contributed
• Date/Time: Tuesday, August 5, 2014 : 8:30 AM to 10:20 AM
• Sponsor: Biopharmaceutical Section
• Author(s): Xiaopeng Miao*+ and Yan Zhou and Narinder Nangia
• Companies: Biogen Idec and University of Michigan and AbbVie
• Keywords: subgroup analysis ; latent models ; placebo response ; pain trials ; longitudinal analysis

Abstract

Large placebo response has been observed in placebo-controlled chronic pain studies in the last decade. Yet the mechanism of the placebo response has not been fully elucidated, making it difficult to assess the efficacy of new analgesic therapies. In this presentation, two latent subgroup analysis models are employed to uncover the pattern of placebo response based on the trajectory shape of the visual analog scale (VAS) scores across time in osteoarthritis (OA) pain studies. Two groups are identified among the placebo subjects, namely the "placebo responders" and "placebo non-responders". Classification models are used to identify subjects' characteristics that may predict the placebo responders. The data from a phase 3 OA pain study is used for the exploratory analysis and the validation is done on the data from a phase 2 OA pain study.