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Journal of Biopharmaceutical Statistics

Samir Salah, Shein-Chung Chow, Fuyu Song
Validation of instrumental evaluation methods or measurement systems plays an important role in both pharmaceutical and cosmetic research and development. In practice, it is suggested that validation should be done according to performance characteristics as described in the United States Pharmacopedia and National Formulary (USP/NF, 2000) for analytical methods validation. A validated method or measurement system is expected to achieve a certain degree of accuracy and reliability. However, it is a concern whether the test results obtained are repeatable (with similar test samples) and/or reproducible (under similar but slightly different experimental conditions)...
December 1, 2016: Journal of Biopharmaceutical Statistics
Meiyu Shen, Stella G Machado
Bioequivalence studies are an essential part of the evaluation of generic drugs. The most common in-vivo bioequivalence study design is the two-period two-treatment crossover design. The observed drug concentration-time profile for each subject from each treatment under each sequence can be obtained. AUC (the area under the concentration-time curve) and Cmax (the maximum concentration) are obtained from the observed drug concentration-time profiles for each subject from each treatment under each sequence. However, such a drug concentration-time profile for each subject from each treatment under each sequence cannot possibly be available during development of generic ophthalmic products since there is only one-time point measured drug concentration of aqueous humor for each eye...
December 1, 2016: Journal of Biopharmaceutical Statistics
Yue-Ming Chen, Yu-Ting Weng, Xiaoyu Dong, Yi Tsong
Equivalence tests may be tested with mean difference against a margin adjusted for variance. The justification of using variance adjusted non-inferiority or equivalence margin is for the consideration that larger margin should be used with large measurement variability. However, under the null hypothesis, the test statistic does not follow a t-distribution or any well-known distribution even when the measurement is normally distributed. In this study, we investigate asymptotic tests for testing equivalence hypothesis...
December 1, 2016: Journal of Biopharmaceutical Statistics
Meiyu Shen, Tianhua Wang, Yi Tsong
In the evaluation of the analytical similarity data, an equivalence testing approach for most critical and quantitative quality attributes, that are assigned to Tier 1 in their proposed three-tier approach, was proposed (Tsong, Dong, and Shen, 2016). Food and Drug Administration (FDA) has recommended the proposed equivalence testing approach to sponsors through meeting comments for Pre-Investigational New Drug Applications (PINDs) and Investigational New Drug Applications (INDs) since 2014. FDA has received some feedbacks on statistical issues of potentially correlated reference lot values subjected to the equivalence testing since independent and identical observations (lot values) from the proposed biosimilar product and the reference product are assumed...
December 1, 2016: 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
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