Biostatistics Commons^™

Multiple-Robust Estimation Of An Odds Ratio Interaction, Eric J. Tchetgen Tchetgen

Harvard University Biostatistics Working Paper Series

No abstract provided.

Inverse Odds Ratio-Weighted Estimation For Causal Mediation Analysis, Eric J. Tchetgen Tchetgen

Harvard University Biostatistics Working Paper Series

No abstract provided.

Racial And Ethnic Differences In Hospice Use Among Patients With Heart Failure, Jane Givens, Jennifer Tjia, Chao Zhou, Ezekiel Emanuel, Arlene Ash

Jennifer Tjia

BACKGROUND: Heart failure is the leading noncancer diagnosis for patients in hospice care and the leading cause of hospitalization among Medicare beneficiaries. Racial and ethnic differences in hospice patients are well documented for patients with cancer but poorly described for those with heart failure.

METHODS: On the basis of a national sample of 98 258 Medicare beneficiaries 66 years and older on January 1, 2001, with a diagnosis of heart failure who had at least 1 physician or hospital encounter and who were not enrolled in hospice care between January 1 and December 31, 2000, we determined the effect of …

Disparities In Combination Drug Therapy Use In Older Adults With Coronary Heart Disease: A Cross-Sectional Time-Series In A Nationally Representative Us Sample, Jennifer Tjia, Becky Briesacher, Dawei Xie, Jason Fu, Robert Goldberg

Jennifer Tjia

BACKGROUND: Despite evidence of effective combination drug therapy for secondary prevention of coronary heart disease (CHD), older adults with this condition remain undertreated.

OBJECTIVE: To describe time trends (1992-2003) in the adoption of combination cardiac drug therapies (beta-blockers [beta-adrenoceptor antagonists], ACE inhibitors or angiotensin II type 1 receptor antagonists [angiotensin receptor blockers; ARBs], and lipid-lowering agents) among older adults in the US with CHD and to identify factors associated with not using combination therapy.

METHODS: The study took the form of a cross-sectional time-series. The study population consisted of a nationally representative sample of adults aged >or=65 years with CHD …

Effect Of Nutrition Changes On Foods Selected By Students In A Middle School-Based Diabetes Prevention Intervention Program: The Healthy Experience, Connie Mobley, Diane D. Stadler, Myrlene A. Staten, Laure El Ghormli, Bonnie Gillis, Jill Hartstein, Anna Maria Siega-Riz, Amy Virus, Healthy Study Group

GW Biostatistics Center

No abstract provided.

Repeat Prenatal Corticosteroid Prior To Preterm Birth: A Systematic Review And Individual Participant Data Meta-Analysis For The Precise Study Group (Prenatal Repeat Corticosteroid International Ipd Study Group: Assessing The Effects Using The Best Level Of Evidence) - Study Protocol, Caroline A. Crowther, Fariba Aghajafari, Lisa M. Askie, Elizabeth V. Asztalos, Peter Brocklehurst, Elizabeth A. Thom, +22 Additional Authors

GW Biostatistics Center

Background

The aim of this individual participant data (IPD) meta-analysis is to assess whether the effects of repeat prenatal corticosteroid treatment given to women at risk of preterm birth to benefit their babies are modified in a clinically meaningful way by factors related to the women or the trial protocol.

Methods/Design

The Prenatal Repeat Corticosteroid International IPD Study Group: assessing the effects using the best level of Evidence (PRECISE) Group will conduct an IPD meta-analysis. The PRECISE International Collaborative Group was formed in 2010 and data collection commenced in 2011. Eleven trials with up to 5,000 women and 6,000 infants …

Sample Size Calculations For Roc Studies: Parametric Robustness And Bayesian Nonparametrics, Dunlei Cheng, Adam J. Branscum, Wesley O. Johnson

Dunlei Cheng

Methods for sample size calculations in ROC studies often assume independent normal distributions for test scores among the diseased and non-diseased populations. We consider sample size requirements under the default two-group normal model when the data distribution for the diseased population is either skewed or multimodal. For these two common scenarios we investigate the potential for robustness of calculated sample sizes under the mis-specified normal model and we compare to sample sizes calculated under a more flexible nonparametric Dirichlet process mixture model. We also highlight the utility of flexible models for ROC data analysis and their importance to study design. …

Trends And Outcomes Associated With Angiotensin-Converting Enzyme Inhibitors, Chyke Doubeni, Carol Bigelow, Darleen Lessard, Frederick Spencer, Jorge Yarzebski, Joel Gore, Jerry Gurwitz, Robert Goldberg

Chyke A. Doubeni

BACKGROUND: Limited recent data are available describing the patterns of use of angiotensin converting enzyme inhibitor (ACEI) therapy in patients with acute myocardial infarction (AMI), particularly from the more generalizable population-based setting. The purpose of this study was to examine trends in the receipt of ACEIs and associated short-term outcomes in patients hospitalized with AMI in a large Northeastern community.

METHODS: We conducted a community-wide study of 7991 patients hospitalized with AMI in all metropolitan Worcester, Massachusetts, medical centers during 8 annual periods between 1990 and 2003.

RESULTS: Among all patients, 44% received ACEI therapy during their acute hospitalization. There …

Treatment Practices And Outcomes Of Patients With Established Peripheral Arterial Disease Hospitalized With Acute Myocardial Infarction In A Community Setting, Frederick Spencer, Darleen Lessard, Chyke Doubeni, Jorge Yarzebski, Joel Gore, Robert Goldberg

Chyke A. Doubeni

BACKGROUND: There are little contemporary data available describing the hospital and long-term outcomes of patients with peripheral arterial disease (PAD) who are hospitalized with acute myocardial infarction (AMI). The objectives of our population-based study were to examine the hospital and long-term outcomes, as well as the use of different treatment practices, among patients with established PAD who were hospitalized with AMI. METHODS: The study sample consisted of 4480 patients hospitalized with AMI at all Worcester, Mass, medical centers in 4 alternate years between 1997 and 2003. RESULTS: Among the metropolitan Worcester residents hospitalized with AMI, 13.5% had a history of …

Alternate Estrogen Receptors Promote Invasion Of Inflammatory Breast Cancer Cells Via Non-Genomic Signaling, Kazufumi Ohshiro, Arnold M. Schwartz, Paul H. Levine, Rakesh Kumar

Epidemiology Faculty Publications

Although Inflammatory Breast Cancer (IBC) is a rare and an aggressive type of locally advanced breast cancer with a generally worst prognosis, little work has been done in identifying the status of non-genomic signaling in the invasiveness of IBC. The present study was performed to explore the status of non-genomic signaling as affected by various estrogenic and anti-estrogenic agents in IBC cell lines SUM149 and SUM190. We have identified the presence of estrogen receptor α (ERα) variant, ERα36 in SUM149 and SUM190 cells. This variant as well as ERβ was present in a substantial concentration in IBC cells. The treatment …

Statistical Methods For Normalization And Analysis Of High-Throughput Genomic Data, Tobias Guennel

Theses and Dissertations

High-throughput genomic datasets obtained from microarray or sequencing studies have revolutionized the field of molecular biology over the last decade. The complexity of these new technologies also poses new challenges to statisticians to separate biological relevant information from technical noise. Two methods are introduced that address important issues with normalization of array comparative genomic hybridization (aCGH) microarrays and the analysis of RNA sequencing (RNA-Seq) studies. Many studies investigating copy number aberrations at the DNA level for cancer and genetic studies use comparative genomic hybridization (CGH) on oligo arrays. However, aCGH data often suffer from low signal to noise ratios resulting …

Targeted Maximum Likelihood Estimation Of Natural Direct Effects, Wenjing Zheng, Mark Van Der Laan

Wenjing Zheng

In many causal inference problems, one is interested in the direct causal effect of an exposure on an outcome of interest that is not mediated by certain intermediate variables. Robins and Greenland (1992) and Pearl (2001) formalized the definition of two types of direct effects (natural and controlled) under the counterfactual framework. The efficient scores (under a nonparametric model) for the various natural effect parameters and their general robustness conditions, as well as an estimating equation based estimator using the efficient score, are provided in Tchetgen Tchetgen and Shpitser (2011b). In this article, we apply the targeted maximum likelihood framework …

Childhood Body Mass Index Trajectories: Modeling, Characterizing, Pairwise Correlations And Socio-Demographic Predictors Of Trajectory Characteristics, Xiaozhong Wen, Ken Kleinman, Matthew W. Gillman, Sherly L. Rifas-Shiman, Elsie M. Taveras

Public Health Department Faculty Publication Series

BACKGROUND:

Modeling childhood body mass index (BMI) trajectories, versus estimating change in BMI between specific ages, may improve prediction of later body-size-related outcomes. Prior studies of BMI trajectories are limited by restricted age periods and insufficient use of trajectory information.

METHODS:

Among 3,289 children seen at 81,550 pediatric well-child visits from infancy to 18 years between 1980 and 2008, we fit individual BMI trajectories using mixed effect models with fractional polynomial functions. From each child's fitted trajectory, we estimated age and BMI at infancy peak and adiposity rebound, and velocity and area under curve between 1 week, infancy peak, adiposity …

Estimation Of Newborn Risk For Child Or Adolescent Obesity:Lessons From Longitudinal Birth Cohorts, Anita Morandi, David Meyre, Stephane Lobbens, Ken Kleinman, Marika Kaakinen, Sheryl L. Rifas-Shiman, Vincent Vatin, Stefan Gaget, Anneli Pouta, Anna-Liisa Hartikainen, Jaana Laitinen, Matthew W. Gillman, Marjo-Riitta Jarvelin, Philippe Froguel

Public Health Department Faculty Publication Series

OBJECTIVES:

Prevention of obesity should start as early as possible after birth. We aimed to build clinically useful equations estimating the risk of later obesity in newborns, as a first step towards focused early prevention against the global obesity epidemic.

METHODS:

We analyzed the lifetime Northern Finland Birth Cohort 1986 (NFBC1986) (N = 4,032) to draw predictive equations for childhood and adolescent obesity from traditional risk factors (parental BMI, birth weight, maternal gestational weight gain, behaviour and social indicators), and a genetic score built from 39 BMI/obesity-associated polymorphisms. We performed validation analyses in a retrospective cohort of 1,503 Italian children …

The Analysis Of Image Feature Robustness Using Cometcloud, Xin Qi, Hyunjoo Kim, Fuyong Xing, Manish Parashar, David J. Foran, Lin Yang

Biostatistics Faculty Publications

The robustness of image features is a very important consideration in quantitative image analysis. The objective of this paper is to investigate the robustness of a range of image texture features using hematoxylin stained breast tissue microarray slides which are assessed while simulating different imaging challenges including out of focus, changes in magnification and variations in illumination, noise, compression, distortion, and rotation. We employed five texture analysis methods and tested them while introducing all of the challenges listed above. The texture features that were evaluated include co-occurrence matrix, center-symmetric auto-correlation, texture feature coding method, local binary pattern, and texton. Due …

Aspirin But Not Ibuprofen Use Is Associated With Reduced Risk Of Prostate Cancer: A Plco Study, F. M. Shebl, L. C. Sakoda, A. Black, J. Koziol, G. L. Andriole, R. Grubb, T. R. Church, D. Chia, Cindy Zhou, +8 Additional Authors

GW Biostatistics Center

Background:

Although most epidemiological studies suggest that non-steroidal anti-inflammatory drug use is inversely associated with prostate cancer risk, the magnitude and specificity of this association remain unclear.

Methods:

We examined self-reported aspirin and ibuprofen use in relation to prostate cancer risk among 29 450 men ages 55–74 who were initially screened for prostate cancer from 1993 to 2001 in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Men were followed from their first screening exam until 31 December 2009, during which 3575 cases of prostate cancer were identified.

Results:

After adjusting for potential confounders, the hazard ratios (HRs) of …

Statistical Methods For Proteomic Biomarker Discovery Based On Feature Extraction Or Functional Modeling Approaches, Jeffrey S. Morris

Jeffrey S. Morris

In recent years, developments in molecular biotechnology have led to the increased promise of detecting and validating biomarkers, or molecular markers that relate to various biological or medical outcomes. Proteomics, the direct study of proteins in biological samples, plays an important role in the biomarker discovery process. These technologies produce complex, high dimensional functional and image data that present many analytical challenges that must be addressed properly for effective comparative proteomics studies that can yield potential biomarkers. Specific challenges include experimental design, preprocessing, feature extraction, and statistical analysis accounting for the inherent multiple testing issues. This paper reviews various computational …

Integrative Bayesian Analysis Of High-Dimensional Multi-Platform Genomics Data, Wenting Wang, Veerabhadran Baladandayuthapani, Jeffrey S. Morris, Bradley M. Broom, Ganiraju C. Manyam, Kim-Anh Do

Jeffrey S. Morris

Motivation: Analyzing data from multi-platform genomics experiments combined with patients’ clinical outcomes helps us understand the complex biological processes that characterize a disease, as well as how these processes relate to the development of the disease. Current integration approaches that treat the data are limited in that they do not consider the fundamental biological relationships that exist among the data from platforms.

Statistical Model: We propose an integrative Bayesian analysis of genomics data (iBAG) framework for identifying important genes/biomarkers that are associated with clinical outcome. This framework uses a hierarchical modeling technique to combine the data obtained from multiple platforms …

R Code: A Non-Iterative Implementation Of Tango's Score Confidence Interval For A Paired Difference Of Proportions, Zhao Yang

Zhao (Tony) Yang, Ph.D.

For matched-pair binary data, a variety of approaches have been proposed for the construction of a confidence interval (CI) for the difference of marginal probabilities between two procedures. The score-based approximate CI has been shown to outperform other asymptotic CIs. Tango’s method provides a score CI by inverting a score test statistic using an iterative procedure. In the developed R code, we propose an efficient non-iterative method with closed-form expression to calculate Tango’s CIs. Examples illustrate the practical application of the new approach.

The Problem Of Partial Ordering In Phase I Clinical Trials, Nolan A. Wages

Nolan A. Wages

No abstract provided.