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Activity Number: 16
Type: Topic Contributed
Date/Time: Sunday, August 4, 2013 : 2:00 PM to 3:50 PM
Sponsor: Biopharmaceutical Section
Abstract - #309596
Title: Adjusting for Discordance Rates
Author(s): Vijay Chauhan*+ and Grace Liu and Sudhakar Rao
Companies: Alpha Stats Inc and Jansen Research Development and Janssen Research & Development
Keywords: discordance ; clinical response ; multi-center ; clinical trials
Abstract:

A high discordance rate between evaluations of clinical response by Investigators and Independent Reviewer Committee (IRC) is a major concern for health care decision-makers and regulatory authorities. We have examined discordance at study center level, and attempted to adjust for discordance using real data as a case study. In this study, the discordance rate was approximately 19%. Odds ratios (OR) were not estimable from the majority of centers because of small sizes, representing about 50% of data. Aggregate OR combined from centers was close to the Hazard Ratio (HR) for the primary efficacy endpoint, progression free survival (PFS). However, the 95% confidence interval (CI) was quite wide because of loss of information. Grouping of centers into regions narrowed the 95% CI, but the aggregate OR was surprisingly larger, indicating some kind of bias. Inconsistency between estimates from centers and regions may be due to high discordance. We applied the values of 1 minus discordance rate as weights in estimating aggregate OR, but it did not make much difference.


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