Epidemiology Commons^™

Political Competition, Relative Deprivation, And Perceived Threat: A Research Note On Anti- Christian Violence In India, Chad Bauman, Tamara Leech

Department of Public Health Scholarship and Creative Works

A preliminary subnational statistical analysis of violence against Christians in contemporary India, this article suggests that whereas the data provide very little support for simple, demographic explanations of this violence, they do more robustly support theories emphasizing the relative status of ethnic and religious minorities (vis-à-vis majorities) and the perception, among Hindus, that Christians (and other minorities) represent a threat to their numerical, political and economic strength.

Flexible Distributed Lag Models Using Random Functions With Application To Estimating Mortality Displacement From Heat-Related Deaths, Roger D. Peng

Johns Hopkins University, Dept. of Biostatistics Working Papers

No abstract provided.

Components Of The Indirect Effect In Vaccine Trials: Identification Of Contagion And Infectiousness Effects, Tyler J. Vanderweele, Eric J. Tchetgen, M. Elizabeth Halloran

COBRA Preprint Series

Vaccination of one person may prevent the infection of another either because (i) the vaccine prevents the first from being infected and from infecting the second or because (ii) even if the first person is infected, the vaccine may render the infection less infectious. We might refer to the first of these mechanisms as a contagion effect and the second as an infectiousness effect. In this paper, for the simple setting of a randomized vaccine trial with households of size two, we use counterfactual theory under interference to provide formal definitions of a contagion effect and an infectiousness effect. Using …

On The Definition Of A Confounder, Tyler J. Vanderweele, Ilya Shpitser

COBRA Preprint Series

The causal inference literature has provided a clear formal definition of confounding expressed in terms of counterfactual independence. The causal inference literature has not, however, produced a clear formal definition of a confounder, as it has given priority to the concept of confounding over that of a confounder. We consider a number of candidate definitions arising from various more informal statements made in the literature. We consider the properties satisfied by each candidate definition, principally focusing on (i) whether under the candidate definition control for all "confounders" suffices to control for "confounding" and (ii) whether each confounder in some context …

Sexuality Education, Eva Goldfarb, Norman A. Constantine

Department of Public Health Scholarship and Creative Works

Sexuality education comprises the lifelong intentional processes by which people learn about themselves and others as sexual, gendered beings from biological, psychological, and sociocultural perspectives. It takes place through a potentially wide range of programs and activities in schools, community settings, religious centers, as well as informally within families, among peers, and through electronic and other media. Sexuality education for adolescents occurs in the context of the biological, cognitive, and social-emotional developmental progressions and issues of adolescence. Formal sexuality education falls into two main categories: behavior change approaches, which are represented by abstinence-only and abstinence-plus models, and healthy sexual development …

Exploration And Comparison Of Methods For Combining Population- And Family-Based Genetic Association Using The Genetic Analysis Workshop 17 Mini-Exome, David W. Fardo, Anthony R. Druen, Jinze Liu, Lucia Mirea, Claire Infante-Rivard, Patrick Breheny

Biostatistics Faculty Publications

We examine the performance of various methods for combining family- and population-based genetic association data. Several approaches have been proposed for situations in which information is collected from both a subset of unrelated subjects and a subset of family members. Analyzing these samples separately is known to be inefficient, and it is important to determine the scenarios for which differing methods perform well. Others have investigated this question; however, no extensive simulations have been conducted, nor have these methods been applied to mini-exome-style data such as that provided by Genetic Analysis Workshop 17. We quantify the empirical power and false-positive …

Assessing Association For Bivariate Survival Data With Interval Sampling: A Copula Model Approach With Application To Aids Study, Hong Zhu, Mei-Cheng Wang

Johns Hopkins University, Dept. of Biostatistics Working Papers

In disease surveillance systems or registries, bivariate survival data are typically collected under interval sampling. It refers to a situation when entry into a registry is at the time of the first failure event (e.g., HIV infection) within a calendar time interval, the time of the initiating event (e.g., birth) is retrospectively identified for all the cases in the registry, and subsequently the second failure event (e.g., death) is observed during the follow-up. Sampling bias is induced due to the selection process that the data are collected conditioning on the first failure event occurs within a time interval. Consequently, the …

Characterization Of Street Food Consumption In Palermo: Possible Effects On Health, Silvio Buscemi, Annamaria Barile, Vincenza Maniaci, John A. Batsis

Dartmouth Scholarship

Background: Street Food (SF) consists of out-of-home food consumption and has old, historical roots with complex social-economic and cultural implications. Despite the emergence of modern fast food, traditional SF persists worldwide, but the relationship of SF consumption with overall health, well-being, and obesity is unknown.

Methods: This is an observational, cross-sectional study. The study was performed in Palermo, the largest town of Sicily, Italy. Two groups were identified: consumers of SF (n = 687) and conventional restaurant food (RES) consumers (n = 315). Study subjects answered a questionnaire concerning their health conditions, nutritional preferences, frequency of consumption of SF and …

Depicting Estimates Using The Intercept In Meta-Regression Models: The Moving Constant Technique, Blair T. Johnson Dr., Tania B. Huedo-Medina Dr.

CHIP Documents

In any scientific discipline, the ability to portray research patterns graphically often aids greatly in interpreting a phenomenon. In part to depict phenomena, the statistics and capabilities of meta-analytic models have grown increasingly sophisticated. Accordingly, this article details how to move the constant in weighted meta-analysis regression models (viz. “meta-regression”) to illuminate the patterns in such models across a range of complexities. Although it is commonly ignored in practice, the constant (or intercept) in such models can be indispensible when it is not relegated to its usual static role. The moving constant technique makes possible estimates and confidence intervals at …

Heterogeneity And Data Analysis, Peter J. Taylor

Working Papers on Science in a Changing World

This working paper is a discussion paper for a September 2011 meeting of the research group of Prof. Di Cook on data visualization and exploratory data analysis at Iowa State University. A taxonomy of eleven kinds of heterogeneity is presented, followed by a set of vignettes that illustrate some of the meanings and sketch some implications, then a series of images that illustrate the heterogeneities. Several of the vignettes speak to a broad contention about heterogeneity and control: In relation to modern understandings of heredity and development over the life course, research and application of resulting knowledge are untroubled by …

A Regularization Corrected Score Method For Nonlinear Regression Models With Covariate Error, David M. Zucker, Malka Gorfine, Yi Li, Donna Spiegelman

Harvard University Biostatistics Working Paper Series

No abstract provided.

Estimation Of Risk Ratios In Cohort Studies With Common Outcomes: A Simple And Efficient Two-Stage Approach, Eric J. Tchetgen

Harvard University Biostatistics Working Paper Series

No abstract provided.

On The Nondifferential Misclassification Of A Binary Confounder, Elizabeth L. Ogburn, Tyler J. Vanderweele

COBRA Preprint Series

Abstract Consider a study with binary exposure, outcome, and confounder, where the confounder is nondifferentially misclassified. Epidemiologists have long accepted the unproven but oft-cited result that, if the confounder is binary, odds ratios, risk ratios, and risk differences which control for the mismeasured confounder will lie between the crude and the true measures. In this paper the authors provide an analytic proof of the result in the absence of a qualitative interaction between treatment and confounder, and demonstrate via counterexample that the result need not hold when there is a qualitative interaction between treatment and confounder. They also present an …

Hiv And Concurrent Sexual Partnerships: Modelling The Role Of Coital Dilution, Larry Sawers, Alan G. Isaac, Eileen Stillwaggon

Economics Faculty Publications

Background: The concurrency hypothesis asserts that high prevalence of overlapping sexual partnerships explains extraordinarily high HIV levels in sub-Saharan Africa. Earlier simulation models show that the network effect of concurrency can increase HIV incidence, but those models do not account for the coital dilution effect (nonprimary partnerships have lower coital frequency than primary partnerships).

Methods: We modify the model of Eaton et al (AIDS and Behavior, September 2010) to incorporate coital dilution by assigning lower coital frequencies to non-primary partnerships. We parameterize coital dilution based on the empirical work of Morris et al (PLoS ONE, December …

Modification By Frailty Status Of Ambient Air Pollution Effects On Lung Function In Older Adults In The Cardiovascular Health Study, Sandrah P. Eckel, Thomas A. Louis, Paulo H.M. Chaves, Linda P. Fried, Helene G. Margolis

Johns Hopkins University, Dept. of Biostatistics Working Papers

Older adult susceptibility to air pollution health effects is well-recognized. Advanced age may act as a partial surrogate for conditions associated with aging. The authors investigated whether gerontologic frailty (a clinical health status metric) modified the effects of ambient ozone or particulate matter (PM10) air pollution on lung function in 3382 older adults using 7 years of followup data from the Cardiovascular Health Study (CHS) and the CHS Environmental Factors Ancillary Study. Monthly average pollution and annual frailty assessments were related to up to 3 repeated measurements of lung function using novel cumulative summaries of pollution and frailty histories that …

The Community Action Framework In Practice: An Illustration Based On The Ready By 21 Coalition Of Austin/Travis County, Raphael Travis Jr., Tamara Leech

Department of Public Health Scholarship and Creative Works

The field of positive youth development has expanded focus from articulating and measuring desired manifestations of positive well-being to assembling the environmental conditions known to promote these desired outcomes. Evidence of the effectiveness of community-level efforts promoting positive youth development is still emerging, in particular theory-driven examples of community-driven youth development. This study examined the Community Action Framework, one theory-based community youth development model, through the experiences of the Ready by 21 Austin/Travis County coalition (RB21). The coalition connects youth-serving organizations and also regional coalitions, while promoting the positive development of area youth. Participant observation, interviewing, and archival strategies were …

Heterogeneity, Control, Social Infrastructure, And Possibilities Of Participation: Their Interplay In Modern Understandings Of Heredity And In Interpretation Of Science, Peter J. Taylor

Working Papers on Science in a Changing World

This working paper is a prospectus for research, writing, and engagement. It consists of vignettes, sketches of lines of inquiry, and proposals for engagement, all of which concern modern understandings of heredity and development over the life course as well as the social interpretation of science. The various items address a range of areas of science and of its interpretation: heritability studies, the social uses of genetic information, gene-by-environment interaction, personalized medicine, IQ paradoxes, racial group membership, biobanks, and life events and difficulties research. Fresh perspectives in these areas are opened up by examining the ways that research and application …

Variable Importance Analysis With The Multipim R Package, Stephan J. Ritter, Nicholas P. Jewell, Alan E. Hubbard

U.C. Berkeley Division of Biostatistics Working Paper Series

We describe the R package multiPIM, including statistical background, functionality and user options. The package is for variable importance analysis, and is meant primarily for analyzing data from exploratory epidemiological studies, though it could certainly be applied in other areas as well. The approach taken to variable importance comes from the causal inference field, and is different from approaches taken in other R packages. By default, multiPIM uses a double robust targeted maximum likelihood estimator (TMLE) of a parameter akin to the attributable risk. Several regression methods/machine learning algorithms are available for estimating the nuisance parameters of the models, including …

Reduced Bayesian Hierarchical Models: Estimating Health Effects Of Simultaneous Exposure To Multiple Pollutants, Jennifer F. Bobb, Francesca Dominici, Roger D. Peng

Johns Hopkins University, Dept. of Biostatistics Working Papers

Quantifying the health effects associated with simultaneous exposure to many air pollutants is now a research priority of the US EPA. Bayesian hierarchical models (BHM) have been extensively used in multisite time series studies of air pollution and health to estimate health effects of a single pollutant adjusted for potential confounding of other pollutants and other time-varying factors. However, when the scientific goal is to estimate the impacts of many pollutants jointly, a straightforward application of BHM is challenged by the need to specify a random-effect distribution on a high-dimensional vector of nuisance parameters, which often do not have an …

Principal Component Analysis Of Dietary And Lifestyle Patterns In Relation To Risk Of Subtypes Of Esophageal And Gastric Cancer, Stephanie A. Navarro Silvera, Susan T. Mayne, Harvey A. Risch, Marilie D. Gammon, Thomas Vaughan, Wong-Ho Chow, Joel A. Dubin, Robert Dubrow, Janet Schoenberg, Janet L. Stanford, A. Brian West, Heidrun Rotterdam, William J. Blot

Department of Public Health Scholarship and Creative Works

Purpose

To carry out pattern analyses of dietary and lifestyle factors in relation to risk of esophageal and gastric cancers.

Methods

We evaluated risk factors for esophageal adenocarcinoma (EA), esophageal squamous cell carcinoma (ESCC), gastric cardia adenocarcinoma (GCA), and other gastric cancers (OGA) using data from a population-based case-control study conducted in Connecticut, New Jersey, and western Washington state. Dietary/lifestyle patterns were created using principal component analysis (PCA). The impact of the resultant scores on cancer risk was estimated through logistic regression.

Results

PCA identified six patterns: meat/nitrite, fruit/vegetable, smoking/alcohol, legume/meat alternate, GERD/BMI, and fish/vitamin C. Risk of each …

Farmwork-Related Injury Among Farmers 50 Years Of Age And Older In Kentucky And South Carolina: A Cohort Study, 2002-2005, Jennifer L. Marcum, Steven R. Browning, Deborah B. Reed, Richard Charnigo

Epidemiology and Environmental Health Faculty Publications

Farmers in the U.S. are becoming more diverse; the average age of the farmer is increasing, as is the number of women and minority farm operators. There is limited research on injury risk factors in these special populations of farmers. It is especially important to study the risk factors for injury in these growing and at-risk groups. A longitudinal survey was conducted of farmers (n = 1,394) age 50 and older who resided in Kentucky and South Carolina. The questionnaire was administered by telephone and mail surveys four times between 2002 and 2005 to the fixed cohort of farmers, obtained …

Perflurorochemical (Pfc) Exposure In Children: Associations With Impaired Response Inhibition, Brooks B. Gump, Qian Wu, Amy K. Dumas, Kurunthachalam Kannan

Falk College Research Center

Background: Perfluorinated chemicals (PFCs) have been used widely in consumer products since the 1950s and are currently found at detectable levels in the blood of humans and animals across the globe. In stark contrast to this widespread exposure to PFCs, there is relatively little research on potential adverse health effects of exposure to these chemicals.Objectives: We performed this cross-sectional study to determine if specific blood PFC levels are associated with impaired response inhibition in children. Methods: Blood levels of 11 PFCs were measured in children (N = 83) and 6 PFCs: perfluorooctane sulfonate (PFOS), perfluorohexane sulfate (PFHxS), perfluorooctanoic acid (PFOA), …

Does Comorbidity Explain The Ethnic Inequalities In Cervical Cancer Survival In New Zealand? A Retrospective Cohort Study, Naomi Brewer, Barry Borman, Diana Sarfati, Mona Jeffreys, Steven T. Fleming, Soo Cheng, Neil Pearce

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: There are large ethnic differences in cervical cancer survival in New Zealand that are only partly explained by stage at diagnosis. We investigated the association of comorbidity with cervical cancer survival, and whether comorbidity accounted for the previously observed ethnic differences in survival.

METHODS: The study involved 1,594 cervical cancer cases registered during 1994-2005. Comorbidity was measured using hospital events data and was classified using the Elixhauser instrument; effects on survival of individual comorbid conditions from the Elixhauser instrument were also assessed. Cox regression was used to estimate adjusted cervical cancer mortality hazard ratios (HRs).

RESULTS: Comorbidity during the …

Eat, Drink And Be Wary, Robert Lannigan

Pathology Presentations

The diversity of foods available and the way we produce, process and distribute them can have consequences in terms of infectious illnesses. This talk by Dr. Robert Lannigan, professor in Western’s Schulich School of Medicine & Dentistry, explores some of these concerns.

Bayesian Effect Estimation Accounting For Adjustment Uncertainty, Chi Wang, Giovanni Parmigiani, Francesca Dominici

Harvard University Biostatistics Working Paper Series

No abstract provided.

Threshold Regression Models Adapted To Case-Control Studies, And The Risk Of Lung Cancer Due To Occupational Exposure To Asbestos In France, Antoine Chambaz, Dominique Choudat, Catherine Huber, Jean-Claude Pairon, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

Asbestos has been known for many years as a powerful carcinogen. Our purpose is quantify the relationship between an occupational exposure to asbestos and an increase of the risk of lung cancer. Furthermore, we wish to tackle the very delicate question of the evaluation, in subjects suffering from a lung cancer, of how much the amount of exposure to asbestos explains the occurrence of the cancer. For this purpose, we rely on a recent French case-control study. We build a large collection of threshold regression models, data-adaptively select a better model in it by multi-fold likelihood-based cross-validation, then fit the …

An Exercise In Molecular Epidemiology: Human Rhinovirus Prevalence And Genitics, Catherine J. Albright, David J. Hall

Chemistry Department Faculty Publications

Human rhinovirus (HRV) is one of the most common human respiratory pathogens and is responsible for the majority of upper respiratory illnesses. Recently, a phylogeny was constructed from all known Ameri- can Type Culture Collection (ATCC) HRV sequences. From this study, three HRV classifications (HRVA, HRVB, and HRVC) were determined and techniques for classifying new isolates of HRV were reported. The genetic change of this virus in specific populations over time is of great interest to understand the evolution and epidemiology of viruses. To facilitate the collections of HRV sequences over a number of years, a virology experiment was designed …

Seropositivity To Cytomegalovirus, Inflammation, All-Cause And Cardiovascular Disease-Related Mortality In The United States, Amanda M. Simanek, Jennifer Beam Dowd, Graham Pawelec, David Melzer, Ambarish Dutta, Allison E. Aiello

Publications and Research

Background: Studies have suggested that CMV infection may influence cardiovascular disease (CVD) risk and mortality. However, there have been no large-scale examinations of these relationships among demographically diverse populations. The inflammatory marker C-reactive protein (CRP) is also linked with CVD outcomes and mortality and may play an important role in the pathway between CMV and mortality. We utilized a U.S. nationally representative study to examine whether CMV infection is associated with all-cause and CVD-related mortality. We also assessed whether CRP level mediated or modified these relationships.

Methodology/Principal Findings: Data come from subjects $25 years of age who were tested for …

Education, Occupation, And Migration As Predictors Of Multiple Sexual Partnerships Among People Tested For Hiv In Luderitz, Namibia, Sima Blank

Masters Theses 1911 - February 2014

Multiple sexual partnerships are associated with greater risk of HIV, sexually transmitted infections (STIs) and intimate partner violence. Namibia has an HIV prevalence of 18% and surveys have shown that up to 40% of men in parts of the country have multiple sexual partners; however, no studies have evaluated characteristics associated with this behavior.

We evaluated the relationship between education, occupation, and migration and multiple sexual partnerships among people tested for HIV in Lüderitz, Namibia. Data are taken from a cross-sectional study of 570 men and women conducted in a Voluntary Counseling and Testing Center from September-November 2009. Multinomial logistic …

Density Of Drinking Establishments And Hiv Prevalence In A Migrant Town In Namibia, Brooke E. Nichols

Masters Theses 1911 - February 2014

Given the established link between alcohol consumption and risk taking behavior, it is plausible that neighborhoods with higher density of drinking establishments will be associated with increased prevalence of HIV. We conducted an ecological study comparing neighborhoods in Luderitz, Namibia, to evaluate this relationship. We observed increased prevalence of HIV comparing high densities of registered and unregistered shebeens, bars, and total number of drinking establishments, as compared with low densities, were associated with increased prevalence of HIV (PR=3.02, 95% CI: 2.04-4.47; PR=1.71, 95% CI: 1.42-2.07; PR=1.55, 95% CI: 1.19-2.02). Our observation of increased prevalence associated with higher densities of drinking …