Christy Chuang-Stein

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A PhRMA Working Group on adaptive clinical trial designs has been formed to investigate and facilitate opportunities for wider acceptance and usage of adaptive designs and related methodologies. A White Paper summarizing the findings of the group is in preparation; this article is an Executive Summary for that full White Paper, and summarizes the findings(More)
In this paper, we examine three approaches for comparing several treatments with a control with use of binary response data. The first approach relies on asymptotic theory applied to the Freeman-Tukey transformation of the observed proportions. The second finds an acceptance region based on the binomial distributions estimated under the joint null(More)
We have examined the regression effect and its magnitude under the Gaussian distributional assumption. The impact and implication of regression to the mean on the analysis of medical investigations was discussed. For simplicity, we called the approach adjusting for the regression effect a two-stage procedure and noted its relationship to the analysis of(More)
Attrition is a ubiquitous problem in randomized controlled clinical trials (RCT) of psychotropic agents that can cause biased estimates of the treatment effect, reduce statistical power, and restrict the generalizability of results. The extent of the problem of attrition in central nervous system (CNS) trials is considered here and its consequences are(More)
This paper describes the distinction between the concept of statistical power and the probability of getting a successful trial. While one can choose a very high statistical power to detect a certain treatment effect, the high statistical power does not necessarily translate to a high success probability if the treatment effect to detect is based on the(More)
BACKGROUND The increasing prevalence of Alzheimer disease (AD) and lack of effective agents to attenuate progression have accelerated research and development of disease modifying (DM) therapies. The traditional parallel group design and single time point analysis used in the support of past AD drug approvals address symptomatic benefit over relatively(More)
Previous research demonstrated a relationship between transfusions of whole blood, or large numbers of red cell concentrates, and later recurrence of cancers of the colon, rectum, cervix, and prostate. It is possible that the transfusion of whole blood may represent a surrogate marker for advanced or more aggressive clinical disease. The relationship of(More)
The US Food and Drug Administration has recently released a draft guidance document on adaptive clinical trials. We comment on the document from the particular perspective of the authors as members of a PhRMA working group on this topic, which has interacted with FDA personnel on adaptive trial issue during recent years. We describe the activities and prior(More)
Clinical trials that compare strategies to optimize antibiotic use are of critical importance but are limited by competing risks that distort outcome interpretation, complexities of noninferiority trials, large sample sizes, and inadequate evaluation of benefits and harms at the patient level. The Antibacterial Resistance Leadership Group strives to(More)
In this paper, we propose a method to discount the observed benefit of a treatment by the observed risk in order to facilitate the benefit-less-risk comparison of treatments in a clinical trial. The discounting, applied to each individual in a trial, utilizes a method proposed by Chuang-Stein and co-authors to consolidate the safety data collected in the(More)