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Biostatistics

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https://www.readbyqxmd.com/read/30596892/estimation-of-high-dimensional-directed-acyclic-graphs-with-surrogate-intervention
#1
Min Jin Ha, Wei Sun
Directed acyclic graphs (DAGs) have been used to describe causal relationships between variables. The standard method for determining such relations uses interventional data. For complex systems with high-dimensional data, however, such interventional data are often not available. Therefore, it is desirable to estimate causal structure from observational data without subjecting variables to interventions. Observational data can be used to estimate the skeleton of a DAG and the directions of a limited number of edges...
December 31, 2018: Biostatistics
https://www.readbyqxmd.com/read/30596887/bayesian-generalized-biclustering-analysis-via-adaptive-structured-shrinkage
#2
Ziyi Li, Changgee Chang, Suprateek Kundu, Qi Long
Biclustering techniques can identify local patterns of a data matrix by clustering feature space and sample space at the same time. Various biclustering methods have been proposed and successfully applied to analysis of gene expression data. While existing biclustering methods have many desirable features, most of them are developed for continuous data and few of them can efficiently handle -omics data of various types, for example, binomial data as in single nucleotide polymorphism data or negative binomial data as in RNA-seq data...
December 31, 2018: Biostatistics
https://www.readbyqxmd.com/read/30596883/estimating-c-level-partial-correlation-graphs-with-application-to-brain-imaging
#3
Yumou Qiu, Xiao-Hua Zhou
Alzheimer's disease (AD) is a chronic neurodegenerative disease that changes the functional connectivity of the brain. The alteration of the strong connections between different brain regions is of particular interest to researchers. In this article, we use partial correlations to model the brain connectivity network and propose a data-driven procedure to recover a $c$-level partial correlation graph based on PET data, which is the graph of the absolute partial correlations larger than a pre-specified constant $c$...
December 31, 2018: Biostatistics
https://www.readbyqxmd.com/read/30590511/bayesian-variable-selection-for-multivariate-zero-inflated-models-application-to-microbiome-count-data
#4
Kyu Ha Lee, Brent A Coull, Anna-Barbara Moscicki, Bruce J Paster, Jacqueline R Starr
Microorganisms play critical roles in human health and disease. They live in diverse communities in which they interact synergistically or antagonistically. Thus for estimating microbial associations with clinical covariates, such as treatment effects, joint (multivariate) statistical models are preferred. Multivariate models allow one to estimate and exploit complex interdependencies among multiple taxa, yielding more powerful tests of exposure or treatment effects than application of taxon-specific univariate analyses...
December 26, 2018: Biostatistics
https://www.readbyqxmd.com/read/30590505/bayesian-inference-of-networks-across-multiple-sample-groups-and-data-types
#5
Elin Shaddox, Christine B Peterson, Francesco C Stingo, Nicola A Hanania, Charmion Cruickshank-Quinn, Katerina Kechris, Russell Bowler, Marina Vannucci
In this article, we develop a graphical modeling framework for the inference of networks across multiple sample groups and data types. In medical studies, this setting arises whenever a set of subjects, which may be heterogeneous due to differing disease stage or subtype, is profiled across multiple platforms, such as metabolomics, proteomics, or transcriptomics data. Our proposed Bayesian hierarchical model first links the network structures within each platform using a Markov random field prior to relate edge selection across sample groups, and then links the network similarity parameters across platforms...
December 26, 2018: Biostatistics
https://www.readbyqxmd.com/read/30590499/non-parametric-frailty-cox-models-for-hierarchical-time-to-event-data
#6
Francesca Gasperoni, Francesca Ieva, Anna Maria Paganoni, Christopher H Jackson, Linda Sharples
We propose a novel model for hierarchical time-to-event data, for example, healthcare data in which patients are grouped by their healthcare provider. The most common model for this kind of data is the Cox proportional hazard model, with frailties that are common to patients in the same group and given a parametric distribution. We relax the parametric frailty assumption in this class of models by using a non-parametric discrete distribution. This improves the flexibility of the model by allowing very general frailty distributions and enables the data to be clustered into groups of healthcare providers with a similar frailty...
December 26, 2018: Biostatistics
https://www.readbyqxmd.com/read/30590456/analysis-in-case-control-sequencing-association-studies-with-different-sequencing-depths
#7
Sixing Chen, Xihong Lin
With the advent of next-generation sequencing, investigators have access to higher quality sequencing data. However, to sequence all samples in a study using next generation sequencing can still be prohibitively expensive. One potential remedy could be to combine next generation sequencing data from cases with publicly available sequencing data for controls, but there could be a systematic difference in quality of sequenced data, such as sequencing depths, between sequenced study cases and publicly available controls...
December 26, 2018: Biostatistics
https://www.readbyqxmd.com/read/30590454/assessing-the-incremental-value-of-new-biomarkers-based-on-or-rules
#8
Lu Wang, Alexander R Luedtke, Ying Huang
In early detection of disease, a single biomarker often has inadequate classification performance, making it important to identify new biomarkers to combine with the existing marker for improved performance. A biologically natural method for combining biomarkers is to use logic rules, e.g., the OR/AND rules. In our motivating example of early detection of pancreatic cancer, the established biomarker CA19-9 is only present in a subclass of cancers; it is of interest to identify new biomarkers present in the other subclasses and declare disease when either marker is positive...
December 26, 2018: Biostatistics
https://www.readbyqxmd.com/read/30590450/inference-on-treatment-effect-modification-by-biomarker-response-in-a-three-phase-sampling-design
#9
Michal Juraska, Ying Huang, Peter B Gilbert
An objective in randomized clinical trials is the evaluation of "principal surrogates," which consists of analyzing how the treatment effect on a clinical endpoint varies over principal strata subgroups defined by an intermediate response outcome under both or one of the treatment assignments. The latter effect modification estimand has been termed the marginal causal effect predictiveness (mCEP) curve. This objective was addressed in two randomized placebo-controlled Phase 3 dengue vaccine trials for an antibody response biomarker whose sampling design rendered previously developed inferential methods highly inefficient due to a three-phase sampling design...
December 26, 2018: Biostatistics
https://www.readbyqxmd.com/read/30590447/response-to-guo-et-al-s-letter-to-the-editor
#10
Youyi Fong, Ying Huang, Maria P Lemos, M Juliana Mcelrath
No abstract text is available yet for this article.
December 26, 2018: Biostatistics
https://www.readbyqxmd.com/read/30590388/sequence-kernel-association-test-for-survival-outcomes-in-the-presence-of-a-non-susceptible-fraction
#11
Lajmi Lakhal-Chaieb, Jacques Simard, Shelley Bull
In this work, we propose a single nucleotide polymorphism set association test for survival phenotypes in the presence of a non-susceptible fraction. We consider a mixture model with a logistic regression for the susceptibility indicator and a proportional hazards regression to model survival in the susceptible group. We propose a joint test to assess the significance of the genetic variant in both logistic and survival regressions simultaneously. We adopt the spirit of SKAT and conduct a variance-component test treating the genetic effects of multiple variants as random...
December 26, 2018: Biostatistics
https://www.readbyqxmd.com/read/30561505/letter-to-the-editor-response-garcia-et-al
#12
Torsten Hothorn
No abstract text is available yet for this article.
December 17, 2018: Biostatistics
https://www.readbyqxmd.com/read/30445524/corrigendum-estimation-of-clinical-trial-success-rates-and-related-parameters
#13
Chi Heem Wong, Kien Wei Siah, Andrew W Lo
No abstract text is available yet for this article.
November 14, 2018: Biostatistics
https://www.readbyqxmd.com/read/30445490/diagnostic-methods-for-uncovering-outcome-dependent-visit-processes
#14
Charles E McCulloch, John M Neuhaus
With the advent of electronic health records, information collected in the course of regular health care is increasingly being used for clinical research. The hope is that the wealth of clinical data and the realistic setting (compared with information derived from highly controlled experiments like randomized trials) will aid in the investigation of determinants of disease and understanding of which treatments are effective in regular practice and for which patients. The availability of information in such databases is often driven by how a patient feels and may therefore be associated with the health outcomes being considered...
November 14, 2018: Biostatistics
https://www.readbyqxmd.com/read/30445420/bayesian-estimation-of-a-semiparametric-recurrent-event-model-with-applications-to-the-penetrance-estimation-of-multiple-primary-cancers-in-li-fraumeni-syndrome
#15
Seung Jun Shin, Jialu Li, Jing Ning, Jasmina Bojadzieva, Louise C Strong, Wenyi Wang
A common phenomenon in cancer syndromes is for an individual to have multiple primary cancers (MPC) at different sites during his/her lifetime. Patients with Li-Fraumeni syndrome (LFS), a rare pediatric cancer syndrome mainly caused by germline TP53 mutations, are known to have a higher probability of developing a second primary cancer than those with other cancer syndromes. In this context, it is desirable to model the development of MPC to enable better clinical management of LFS. Here, we propose a Bayesian recurrent event model based on a non-homogeneous Poisson process in order to obtain penetrance estimates for MPC related to LFS...
November 14, 2018: Biostatistics
https://www.readbyqxmd.com/read/30418529/subdistribution-hazard-models-for-competing-risks-in-discrete-time
#16
Moritz Berger, Matthias Schmid, Thomas Welchowski, Steffen Schmitz-Valckenberg, Jan Beyersmann
A popular modeling approach for competing risks analysis in longitudinal studies is the proportional subdistribution hazards model by Fine and Gray (1999. A proportional hazards model for the subdistribution of a competing risk. Journal of the American Statistical Association94, 496-509). This model is widely used for the analysis of continuous event times in clinical and epidemiological studies. However, it does not apply when event times are measured on a discrete time scale, which is a likely scenario when events occur between pairs of consecutive points in time (e...
November 9, 2018: Biostatistics
https://www.readbyqxmd.com/read/30380025/sparse-relative-risk-regression-models
#17
Ernst C Wit, Luigi Augugliaro, Hassan Pazira, Javier González, Fentaw Abegaz
Clinical studies where patients are routinely screened for many genomic features are becoming more routine. In principle, this holds the promise of being able to find genomic signatures for a particular disease. In particular, cancer survival is thought to be closely linked to the genomic constitution of the tumor. Discovering such signatures will be useful in the diagnosis of the patient, may be used for treatment decisions and, perhaps, even the development of new treatments. However, genomic data are typically noisy and high-dimensional, not rarely outstripping the number of patients included in the study...
October 30, 2018: Biostatistics
https://www.readbyqxmd.com/read/30380020/power-analysis-in-a-smart-design-sample-size-estimation-for-determining-the-best-embedded-dynamic-treatment-regime
#18
William J Artman, Inbal Nahum-Shani, Tianshuang Wu, James R Mckay, Ashkan Ertefaie
Sequential, multiple assignment, randomized trial (SMART) designs have become increasingly popular in the field of precision medicine by providing a means for comparing more than two sequences of treatments tailored to the individual patient, i.e., dynamic treatment regime (DTR). The construction of evidence-based DTRs promises a replacement to ad hoc one-size-fits-all decisions pervasive in patient care. However, there are substantial statistical challenges in sizing SMART designs due to the correlation structure between the DTRs embedded in the design (EDTR)...
October 30, 2018: Biostatistics
https://www.readbyqxmd.com/read/30380012/a-novel-calibration-framework-for-survival-analysis-when-a-binary-covariate-is-measured-at-sparse-time-points
#19
Daniel Nevo, Tsuyoshi Hamada, Shuji Ogino, Molin Wang
The goals in clinical and cohort studies often include evaluation of the association of a time-dependent binary treatment or exposure with a survival outcome. Recently, several impactful studies targeted the association between initiation of aspirin and survival following colorectal cancer (CRC) diagnosis. The value of this exposure is zero at baseline and may change its value to one at some time point. Estimating this association is complicated by having only intermittent measurements on aspirin-taking. Commonly used methods can lead to substantial bias...
October 30, 2018: Biostatistics
https://www.readbyqxmd.com/read/30371749/array-testing-for-multiplex-assays
#20
Peijie Hou, Joshua M Tebbs, Dewei Wang, Christopher S McMahan, Christopher R Bilder
Group testing involves pooling individual specimens (e.g., blood, urine, swabs, etc.) and testing the pools for the presence of disease. When the proportion of diseased individuals is small, group testing can greatly reduce the number of tests needed to screen a population. Statistical research in group testing has traditionally focused on applications for a single disease. However, blood service organizations and large-scale disease surveillance programs are increasingly moving towards the use of multiplex assays, which measure multiple disease biomarkers at once...
October 26, 2018: Biostatistics
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