Digital Commons Network^™

The Relationship Between Mosquito Abundance And Rice Field Density In The Republic Of Korea, Erin E. Richards, Penny Masuoka, David Brett-Major, Matthew Smith, Terry A. Klein, Heung Chul Kim, Assaf Anyamba, John Grieco

Journal Articles: Epidemiology

BACKGROUND: Japanese encephalitis virus (JEV), the causative agent of Japanese encephalitis (JE), is endemic to the Republic of Korea (ROK) where unvaccinated United States (U.S.) military Service members, civilians and family members are stationed. The primary vector of the JEV in the ROK is Culex tritaeniorhynchus. The ecological relationship between Culex spp. and rice fields has been studied extensively; rice fields have been shown to increase the prevalence of Cx. tritaeniorhynchus. This research was conducted to determine if the quantification of rice field land cover surrounding U.S. military installations in the ROK should be used as a parameter in a …

The Effects Of Physical Activity And Nutrient Intake On The Risk Of Hip Fracture : Results From The Adventist Health Study-2, Wen-Ling Liao

Loma Linda University Electronic Theses, Dissertations & Projects

This is a two year of follow up study of Adventist Health Study-2 (AHS-2). We assessed the association between physical activity, nutrient intake and risk of hip fracture among peri- and post menopausal Caucasian women using unconditional logistic regression models. All subjects completed a lifestyle questionnaire which including information of physical activity and frequency and portion size of food intake at enrollment into the study (2002-2007). The “Bi-Annual Hospitalization History” questionnaire which included a question about hip fractures due to minor trauma/falls was sent to subjects approximately two years after enrollment, with a response rat of 82.84%. In this cohort, …

Doubly Robust Ecological Inference, Daniel B. Rubin, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

The ecological inference problem is a famous longstanding puzzle that arises in many disciplines. The usual formulation in epidemiology is that we would like to quantify an exposure-disease association by obtaining disease rates among the exposed and unexposed, but only have access to exposure rates and disease rates for several regions. The problem is generally intractable, but can be attacked under the assumptions of King's (1997) extended technique if we can correctly specify a model for a certain conditional distribution. We introduce a procedure that it is a valid approach if either this original model is correct or if we …

The Association Between Adult Self-Reported Asthma & Potential Exposures To Asthma Triggers In Virginia Workplaces: An Ecological Study, Jeanette R. Bowman

Theses and Dissertations

Introduction: Work-related asthma (WRA) is thought to be the most common occupational lung disease in the U.S., but there is no standard case definition of WRA. Most states, including Virginia, do not require WRA diagnoses to be reported to health departments. At present, there is too little epidemiological data on WRA in Virginia to direct public health planning efforts. Objectives: The first objective of this study was to estimate potential exposure to workplace asthma triggers in each of Virginia's 35 health districts. The second objective was to examine associations at the health district level between workplace asthma triggers, other asthma …

Prevalensi Dan Determinan Hipertensi Di Pulau Jawa, Tahun 2004, Zamhir Setiawan

Kesmas

Hipertensi merupakan faktor risiko utama kardiovaskuler yang merupakan penyebab utama kematian di seluruh dunia. Peningkatan umur harapan hidup dan perubahan gaya hidup meningkatkan faktor risiko hipertensi di berbagai negara. Tujuan penelitian ini (1) Mengetahui prevalensi hipertensi dan penyebarannya di Pulau Jawa tahun 2004. (2) Mengetahui faktor-faktor sosiodemografi yang berhubungan dengan kejadian hipertensi. (3) Mengetahui kontribusi dan dampak potensial masing masing faktor tersebut. Penelitian dengan rancangan studi Ekologi Multilevel ini menggabungkan variabel tingkat pengukuran individu dengan tingkat pengukuran ekologi dalam analisis bersama, dengan unit analisis individu. Analisis kontekstual dilakukan melalui kerangka konsep hipertensi, menggunakan metode analisis regresi logistik ganda, dengan status …

Statistical Analysis Of Air Pollution Panel Studies: An Illustration, Holly Janes, Lianne Sheppard, Kristen Shepherd

UW Biostatistics Working Paper Series

The panel study design is commonly used to evaluate the short-term health effects of air pollution. Standard statistical methods for analyzing longitudinal data are available, but the literature reveals that the techniques are not well understood by practitioners. We illustrate these methods using data from the 1999 to 2002 Seattle panel study. Marginal, conditional, and transitional approaches for modeling longitudinal data are reviewed and contrasted with respect to their parameter interpretation and methods for accounting for correlation and dealing with missing data. We also discuss and illustrate techniques for controlling for time-dependent and time-independent confounding, and for exploring and summarizing …

Hierarchical Models For Combining Ecological And Case-Control Data, Sebastien Haneuse, Jon Wakefield

UW Biostatistics Working Paper Series

The ecological study design suffers from a broad range of biases that result from the loss of information regarding the joint distribution of individual-level outcomes, exposures and confounders. The consequent non-identifiability of individual-level models cannot be overcome without additional information; we combine ecological data with a sample of individual-level case-control data. The focus of this paper is hierarchical models to account for between-group heterogeneity. Estimation and inference pose serious compu- tational challenges. We present a Bayesian implementation, based on a data augmentation scheme where the unobserved data are treated as auxiliary variables. The methods are illustrated with a dataset of …

Disease Mapping And Spatial Regression With Count Data, Jon Wakefield

UW Biostatistics Working Paper Series

In this paper we provide critical reviews of methods suggested for the analysis of aggregate count data in the context of disease mapping and spatial regression. We introduce a new method for picking prior distributions, and propose a number of refinements of previously-used models. We also consider ecological bias, mutual standardization, and choice of both spatial model and prior specification. We analyze male lip cancer incidence data collected in Scotland over the period 1975–1980, and outline a number of problems with previous analyses of these data. A number of recommendations are provided. In disease mapping studies, hierarchical models can provide …

A Hybrid Model For Reducing Ecological Bias, Ruth Salway, Jon Wakefield

UW Biostatistics Working Paper Series

A major drawback of epidemiological ecological studies, in which the association between area-level summaries of risk and exposure are used to make inference about individual risk, is the difficulty in characterising within-area variability in exposure and confounder variables. To avoid ecological bias, samples of individual exposure/confounder data within each area are required. Unfortunately these may be difficult or expensive to obtain, particularly if large samples are required. In this paper we propose a new approach suitable for use with small samples. We combine a Bayesian non-parametric Dirichlet process prior with an estimating functions approach, and show that this model gives …

Health-Exposure Modelling And The Ecological Fallacy, Jon Wakefield, Gavin Shaddick

UW Biostatistics Working Paper Series

Recently there has been increased interest in modelling the association between aggregate disease counts and environmental exposures measured, for example via air pollution monitors, at point locations. This paper has two aims: first we develop a model for such data in order to avoid ecological bias; second we illustrate that modelling the exposure surface and estimating exposures may lead to bias in estimation of health effects. Design issues are also briefly considered, in particular the loss of information in moving from individual to ecological data, and the at-risk populations to consider in relation to the pollution monitor locations. The approach …

Chronic Arsenic Exposure And Risk Of Infant Mortality In Two Areas Of Chile, Claudia Hopenhayn-Rich, Steven R. Browning, Irva Hertz-Picciotto, Catterina Ferreccio, Cecilia Peralta, Herman Gibb

Preventive Medicine and Environmental Health Faculty Publications

Chronic arsenic exposure has been associated with a range of neurologic, vascular, dermatologic, and carcinogenic effects. However, limited research has been directed at the association of arsenic exposure and human reproductive health outcomes. The principal aim of this study was to investigate the trends in infant mortality between two geographic locations in Chile: Antofagasta, which has a well-documented history of arsenic exposure from naturally contaminated water, and Valparaíso, a comparable low-exposure city. The arsenic concentration in Antofagasta's public drinking water supply rose substantially in 1958 with the introduction of a new water source, and remained elevated until 1970. We used …

Parasite Biodiversity And Emerging Pathogens: A Role For Systematics In Limiting Impacts On Genetic Resources, Eric P. Hoberg

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Emergence of pathogenic organisms continues as a threat to overall biodiversity and genetic resources. Macroparasites including helminths constitute a potential threat to economically important resources in agriculture and conservation biology. Limitation of this threat can be achieved through survey and inventory for biodiversity and the application of systematics to understand the host range , biogeography and history of faunas. Systematics constitutes the foundation for recognition of endemic and introduced elements of faunas and the basis for predicting the behavior of pathogens introduced to new ecological settings or host groups. The basis for emergence of pathogens has both a deep historical …

Case-Control Study Of Vitamin A Intake And Colorectal Cancer In Seventh-Day Adventists, John William Morgan

Loma Linda University Electronic Theses, Dissertations & Projects

Colorectal cancer is the second most common cause of cancer deaths in Americans; producing approximately 60,000 deaths in Americans each year. Studies of high and low risk populations have suggested a dietary etiology for colorectal cancer, although investigations of specific dietary factors have produced inconsistent results.

Population based studies of California Seventh-day Adventists demonstrate dietary variety regarding factors suspected as important in the etiology of colorectal cancer. These studies document a substantially reduced mortality and incidence from colorectal cancer in Seventh-day Adventists when compared to other California Populations. Although specific reasons for this difference remain obscure, the 'Unique lifestyle and …