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Journal of Biopharmaceutical Statistics

Terri D Pigott
No abstract text is available yet for this article.
September 28, 2016: Journal of Biopharmaceutical Statistics
Nobushige Matsuoka, Norisuke Kawai
No abstract text is available yet for this article.
September 28, 2016: Journal of Biopharmaceutical Statistics
Mohammad F Huque, Thamban Valappil, Mohamed Alosh, Guoxing Soon
Unmet medical need exits for serious bacterial diseases caused by multi-drug resistant infections necessitating urgent need for newer therapies with greater treatment benefits to patients. For meeting this need, the usual approach has been to conduct separate clinical trials, each trial targeting infection at a single body-site, e.g., for respiratory tract, intra-abdominal site, urinary tract, or blood. However, for the unmet medical need situations, this approach seems inefficient for developing antibacterial drugs with activity against single species or against multiple species of bacteria for a broader indication...
September 26, 2016: Journal of Biopharmaceutical Statistics
Yunqi Bu, Xiao-Hua Zhou
Personalized medicine is an area of growing attention in medical research and practice. A market-ready companion diagnostic test (CDx) is used in personalized medicine for identifying the best treatment for an individual patient. Unfortunately, development of CDx may lag behind the development of the drug, and consequently we use a clinical trial assay (CTA) to enroll patients into the drug pivotal clinical trial instead. Thus, when CDx becomes available, a bridging study will be required to assess the drug efficacy in the CDx intended use (CDx IU) population...
September 20, 2016: Journal of Biopharmaceutical Statistics
Donald B Rubin
The wise use of statistical ideas in practice essentially requires some Bayesian thinking, in contrast to the classical rigid frequentist dogma. This dogma too often has seemed to influence the applications of statistics, even at agencies like the FDA. Greg Campbell was one of the most important advocates there for more nuanced modes of thought, especially Bayesian statistics. Because two brilliant statisticians, Ronald Fisher and Jerzy Neyman, are often credited with instilling the traditional frequentist approach in current practice, I argue that both men were actually seeking very Bayesian answers, and neither would have endorsed the rigid application of their ideas...
September 9, 2016: Journal of Biopharmaceutical Statistics
Ignacio Vidal, Mário de Castro
The agreement of different measurement methods is an important issue in several disciplines like, for example, Medicine, Metrology, and Engineering. In this article, some agreement measures, common in the literature, were analyzed from a Bayesian point of view. Posterior inferences for such agreement measures were obtained based on well-known Bayesian inference procedures for the bivariate normal distribution. As a consequence, a general, simple, and effective method is presented, which does not require Markov Chain Monte Carlo methods and can be applied considering a great variety of prior distributions...
August 25, 2016: Journal of Biopharmaceutical Statistics
Michael C Sachs, Lisa M McShane
Omics technologies that generate a large amount of molecular data characterizing biospecimens have the potential to provide information about patients' disease characteristics above and beyond standard clinical features. By combining information from a large number of features into a multivariable model, called a biomarker signature, there is the opportunity to identify distinct subgroups of patients for whom treatment decisions can be personalized. The key challenge is to derive a signature with good performance and appropriately characterize its performance...
August 25, 2016: Journal of Biopharmaceutical Statistics
Gene Pennello, Norberto Pantoja-Galicia, Scott Evans
Comparing diagnostic tests on accuracy alone can be inconclusive. For example, a test may have better sensitivity than another test yet worse specificity. Comparing tests on benefit risk may be more conclusive because clinical consequences of diagnostic error are considered. For benefit-risk evaluation, we propose diagnostic yield, the expected distribution of subjects with true positive, false positive, true negative, and false negative test results in a hypothetical population. We construct a table of diagnostic yield that includes the number of false positive subjects experiencing adverse consequences from unnecessary work-up...
August 22, 2016: Journal of Biopharmaceutical Statistics
Margaret Gamalo-Siebers, Ram Tiwari, Lisa LaVange
The paradigm shift towards precision medicine reignited interest in determining whether there are differential treatment effects in subgroups of trial participants. Intrinsic to this problem is that any assessment of a differential treatment effect is predicated on being able to estimate the treatment response accurately while satisfying constraints of balancing the risk of overlooking an important subgroup with the potential to make a decision based on a false discovery. While shrinkage models have been widely used to improve accuracy of subgroup parameter estimates by leveraging the relationship between them, there is still a possibility that it can lead to excessively conservative or anti-conservative results...
August 22, 2016: Journal of Biopharmaceutical Statistics
Mixia Wu, Dianchen Zhang, Aiyi Liu
New biomarkers continue to be developed for the purpose of diagnosis, and their diagnostic performances are typically compared with an existing reference biomarker used for the same purpose. Considerable amounts of research have focused on receiver operating characteristic curves analysis when the reference biomarker is dichotomous. In the situation where the reference biomarker is measured on a continuous scale and dichotomization is not practically appealing, an index was proposed in the literature to measure the accuracy of a continuous biomarker, which is essentially a linear function of the popular Kendall's tau...
August 22, 2016: Journal of Biopharmaceutical Statistics
Aiyi Liu, Lilly Q Yue
No abstract text is available yet for this article.
August 22, 2016: Journal of Biopharmaceutical Statistics
John Collins, Paul S Albert
There is a wide body of literature in biostatistics and epidemiology literature about estimating diagnostic accuracy, such as sensitivity and specificity of a binary test, without a gold standard. This methodology is very attractive since obtaining gold standard information is impossible, difficult, or very expensive in some situations. Although there are many proponents of these approaches, there have also been some serious criticisms. We review important methodological developments as well as discuss problems with the approaches...
August 22, 2016: Journal of Biopharmaceutical Statistics
Cynthia Basu, Mariam A Ahmed, Reena V Kartha, Richard C Brundage, Gerald V Raymond, James C Cloyd, Bradley P Carlin
X-linked adrenoleukodystrophy (X-ALD) is a rare, progressive, and typically fatal neurodegenerative disease. Lorenzo's oil (LO) is one of the few X-ALD treatments available, but little has been done to establish its clinical efficacy or indications for its use. In this article, we analyze data on 116 male asymptomatic pediatric patients who were administered LO. We offer a hierarchical Bayesian statistical approach to understand LO pharmacokinetics (PK) and pharmacodynamics (PD) resulting from an accumulation of very long-chain fatty acids...
August 22, 2016: Journal of Biopharmaceutical Statistics
Judy X Li, Wei-Chen Chen, John A Scott
A common question in clinical studies is how to use historical data from earlier studies, leveraging relevant information into the design and analysis of a new study. Bayesian approaches are particularly well-suited to this task, with their natural ability to borrow strength across data sources. In this paper, we propose an eMAP approach for incorporating historical data into the analysis of clinical studies, and we discuss an application of this method to the analysis of observational safety studies for a class of products for patients with hemophilia A...
August 19, 2016: Journal of Biopharmaceutical Statistics
Tinghui Yu, Qin Li, Gerry Gray, Lilly Q Yue
Due to rapid technological development, innovations in diagnostic devices are proceeding at an extremely fast pace. Accordingly, the needs for adopting innovative statistical methods have emerged in the evaluation of diagnostic devices. Statisticians in the Center for Devices and Radiological Health at the Food and Drug Administration have provided leadership in implementing statistical innovations. The innovations discussed in this article include: the adoption of bootstrap and Jackknife methods, the implementation of appropriate multiple reader multiple case study design, the application of robustness analyses for missing data, and the development of study designs and data analyses for companion diagnostics...
August 19, 2016: Journal of Biopharmaceutical Statistics
Zhiwei Zhang, Jianxiong Chu, Dewi Rahardja, Hui Zhang, Li Tang
In clinical trials, it is common practice to categorize subjects as responders and non-responders on the basis of one or more clinical measurements under pre-specified rules. Such a responder analysis is often criticized for the loss of information in dichotomizing one or more continuous or ordinal variables. It is worth noting that a responder analysis can be performed without dichotomization, because the proportion of responders for each treatment can be derived from a model for the original clinical variables (used to define a responder) and estimated by substituting maximum likelihood estimators of model parameters...
August 19, 2016: Journal of Biopharmaceutical Statistics
Lilly Q Yue, Gregory Campbell, Nelson Lu, Yunling Xu, Bram Zuckerman
Regulatory decisions are made based on the assessment of risk and benefit of medical devices at the time of pre-market approval and subsequently, when post-market risk-benefit balance needs reevaluation. Such assessments depend on scientific evidence obtained from pre-market studies, post-approval studies, post-market surveillance studies, patient perspective information, as well as other real world data such as national and international registries. Such registries provide real world evidence and are playing a more and more important role in enhancing the safety and effectiveness evaluation of medical devices...
August 19, 2016: Journal of Biopharmaceutical Statistics
Meiyu Shen, Estelle Russek-Cohen, Eric V Slud
Bioequivalence (BE) studies are an essential part of the evaluation of generic drugs. The most common in vivo BE study design is the two-period two-treatment crossover design. AUC (area under the concentration-time curve) and Cmax (maximum concentration) are obtained from the observed concentration-time profiles for each subject from each treatment under each sequence. In the BE evaluation of pharmacokinetic crossover studies, the normality of the univariate response variable, e.g. log(AUC)(1) or log(Cmax), is often assumed in the literature without much evidence...
August 12, 2016: Journal of Biopharmaceutical Statistics
Changyu Shen, Ziyue Liu, Huiping Xu, Hai Liu, Cynthia Yue
Randomized Phase III clinical trials serve as the gold-standard for the evaluation of the efficacy of a medical intervention. Although research and development in earlier stages together with rigorous statistical examination assure a small probability of false positive for a given trial, it is unclear how many false positives were generated from the large number of randomized Phase III trials from the biopharmaceutical industry in the United States. The proportion of comparisons in Phase III trials where the medical intervention has null or negative efficacy, or proportion of null or negative (PNN), is at the central position for the estimation and control of the number of false positives...
August 12, 2016: Journal of Biopharmaceutical Statistics
Yijie Zhou, Lu Cui, Bo Yang, Lanju Zhang, Frank Shen
It is common in multi-regional clinical development that data from a global trial and a local trial (in a target country) together will be used to support local filing in the target country. This approach is considered efficient drug development both globally and in the target country. However it remains a challenge how to combine global trial data and local trial data toward local filing. To address this challenge, we propose an 'interpretation-centric' evaluation criterion based on a weighted estimator that weights data from the target country and outside of the target country...
June 17, 2016: Journal of Biopharmaceutical Statistics
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