Public Health Commons^™

Nonparametric Regression Using Local Kernel Estimating Equations For Correlated Failure Time Data, Zhangsheng Yu, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.

Causal Inference In Hybrid Intervention Trials Involving Treatment Choice, Qi Long, Rod Little, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.

A Comparison Of Methods For Estimating The Causal Effect Of A Treatment In Randomized Clinical Trials Subject To Noncompliance, Rod Little, Qi Long, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.

Infestasi Kecacingan Pada Anak Sd Di Kecamatan Sei Bingai Langkat, Sumut, 2005, Limin Ginting

Kesmas

Indonesia masih menghadapi masalah kesehatan yang berhubungan dengan kondisi lingkungan yang jelek, seperti infestasi cacing usus yang ditularkan melalui tanah (Soil Transmitted Helminths). Infestasi cacing pada anak akan mengganggu pertumbuhan, menurunkan kemampuan fisik, produktifitas belajar dan intelektualitas. Hasil Pemeriksaan yang dilakukan di beberapa SD di Kecamatan Stabat dan Kecamatan Hinai menemukan prevalensi kecacingan berada pada kisaran 30-60%. Penelitian ini bertujuan untuk menilai prevalensi infestasi kecacingan pada anak SD di Kecamatan Sei Bingai, Kabupaten Langkat serta mengetahui faktor-faktor yang mempengaruhinya. Penelitian dengan disain studi kasus kontrol ini dilakukan di 4 SD Kecamatan Sei Bingai, Kabupaten Langkat, Propinsi Sumatera Utara. Populasi adalah …

Epidemiologi Diskriptif Penyakit Avian Flu Di Lima Provinsi Di Indonesia, 2005-2006, Ajeng Tias Endarti, Ratna Djuwita

Kesmas

Jumlah kasus flu burung pada manusia meningkat sangat pesat. Studi ini bertujuan untuk mengetahui gambaran epidemiologi penyakit flu burung (Avian Influenza/AI) pada kejadian luar biasa di 5 provinsi Indonesia in 2005-2006. Studi ini mengunakan sumber data sekunder data surveilens, sub direktorat Surveilens, Depkes RI, pada periode Juli 2005-2006. Dari 28 kasus konfirmasi ditemukan banyak pada pria (57.1%). Sekitar 89.3% kasus memperlihatkan gejala demam tinggi (>38°C), batuk dan masalah pernapasan dan sekitar 80% diantaranya meninggal dunia. Gejala tersebut mengindikasikan kerusakan jaringan paru-paru pada tubuh penderita. Berdasarkan laporan hasil pemeriksaan laboratorium, terlihat bahwa 60.7% penderita mengalami penurunan kadar leukosit (leucopenia) dan …

Relative Risk Regression In Medical Research: Models, Contrasts, Estimators, And Algorithms, Thomas Lumley, Richard Kronmal, Shuangge Ma

UW Biostatistics Working Paper Series

The relative risk or prevalence ratio is a natural and familiar summary of association between a binary outcome and an exposure or intervention. For rare events, the relative risk can be approximately estimated by logistic regression. For common events estimation is more difficult. We review proposed estimation algorithms for relative risk regression. Some of these give inconsistent estimates or invalid standard errors. We show that the methods that give correct inference can be viewed as arising from a family of quasilikelihood estimating functions for the same generalized linear model, differing in their efficiency and in their robustness to outlying values …

Investigating Mediation When Counterfactuals Are Not Metaphysical: Does Sunlight Uvb Exposure Mediate The Effect Of Eyeglasses On Cataracts?, Brian Egleston, Daniel O. Scharfstein, Beatriz Munoz, Sheila West

Johns Hopkins University, Dept. of Biostatistics Working Papers

We investigate the degree to which a reduction in ocular sunlight ultra-violet B (UVB) exposure mediates a relationship between wearing eyeglasses and a decreased risk of cataracts. An estimand is proposed in which causal effects are estimated locally within strata based on potential UVB exposure without glasses and the degree to which glasses use reduces UVB exposure. We take advantage of the structure of the data in which the counterfactual UVB exposures if the participants in the study who wore glasses had not worn glasses are considered observable.

Causal Comparisons In Randomized Trials Of Two Active Treatments: The Effect Of Supervised Exercise To Promote Smoking Cessation, Jason Roy, Joseph W. Hogan

COBRA Preprint Series

In behavioral medicine trials, such as smoking cessation trials, two or more active treatments are often compared. Noncompliance by some subjects with their assigned treatment poses a challenge to the data analyst. Causal parameters of interest might include those defined by subpopulations based on their potential compliance status under each assignment, using the principal stratification framework (e.g., causal effect of new therapy compared to standard therapy among subjects that would comply with either intervention). Even if subjects in one arm do not have access to the other treatment(s), the causal effect of each treatment typically can only be identified from …

Analysis Of An Sirs Age-Structured Epidemic Model With Vaccination And Vertical Transmission Of Disease, Mohammed El-Doma

Applications and Applied Mathematics: An International Journal (AAM)

An SIRS age-structured epidemic model for a vertically as well as horizontally transmitted disease under vaccination is investigated when the fertility, mortality and removal rates depend on age and the force of infection of proportionate mixing assumption type, and vaccination wanes over time. We prove the existence and uniqueness of solution to the model equations, and show that solutions of the model equations depend continuously on the initial age-distributions. Furthermore, we determine the steady states and obtain an explicitly computable threshold condition, in terms of the demographic and epidemiological parameters of the model; we then study the stability of the …

Low Birth Weight, Very Low Birth Weight And Infant Mortality In San Bernardino County : A Secondary Analysis Of Maternal Factors, Rebecca D. Nanyonjo

Loma Linda University Electronic Theses, Dissertations & Projects

Purpose: National and state infant mortality rates have slowly declined over the last several years. Despite this reduction, San Bernardino County still has one of the highest infant mortality rates in California and racial disparities between Black and White infants not only persist but continue to widen. These disparities remain at the forefront of concern. Healthy People 2010 target objectives have yet to be reached, while national and state proposed plans have supported the statement that a community's largest health problem is initiated by its infant mortality. The purpose of this study was to investigate maternal factors through use of …

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 …

Semiparametric Latent Variable Regression Models For Spatio-Temporal Modeling Of Mobile Source Particles In The Greater Boston Area, Alexandros Gryparis, Brent A. Coull, Joel Schwartz, Helen H. Suh

Harvard University Biostatistics Working Paper Series

Traffic particle concentrations show considerable spatial variability within a metropolitan area. We consider latent variable semiparametric regression models for modeling the spatial and temporal variability of black carbon and elemental carbon concentrations in the greater Boston area. Measurements of these pollutants, which are markers of traffic particles, were obtained from several individual exposure studies conducted at specific household locations as well as 15 ambient monitoring sites in the city. The models allow for both flexible, nonlinear effects of covariates and for unexplained spatial and temporal variability in exposure. In addition, the different individual exposure studies recorded different surrogates of traffic …

Perceived Smoking Environment And Smoking Initiation Among Multi-Ethnic Urban Girls, Tracy R. Nichols, Amanda Birnbaum, Sara Birnel, Gilbert J. Botvin

Department of Public Health Scholarship and Creative Works

Purpose

To examine associations between the perceived smoking environment and smoking initiation among urban multi-ethnic adolescent girls in New York City.

Methods

Self-report surveys completed in grades 7, 8, and 9 assessed girls’ (n = 858) smoking initiation, and perceived smoking environment (family smoking, friends’ smoking, smoking norms, and cigarette availability). Carbon monoxide breath samples were collected from girls using a variation of the bogus pipeline procedure.

Results

Differences were found in smoking prevalence with white girls reporting the highest prevalence of smoking at baseline and the greatest increase in smoking prevalence from seventh to eighth grade. Black girls reported …

The Human Ecology Of A Disease: Dissemination Of Resources And Information On Hiv And Aids In Can Tho City And An Giang Province, Lucas Thornblade

Independent Study Project (ISP) Collection

HIV has spread worldwide. This virus, resulting in as-of-yet incurable destruction of the human immune system, has caused the death of millions in the last two decades through opportunistic infections manifest as AIDS. Though development of prevention and treatment measures have greatly improved in recent years, because of lack of resources, incidence of infection continues to increase annually in nearly all parts of the world including southeast Asia. This paper looks at how the disease has affected people’s lives in Can Tho City and An Giang Province in Vietnam’s southern Mekong Delta. This paper offers an epidemiological and biological argument …

Different Public Health Interventions Have Varying Effects, Paula Diehr, Anne B. Newman, Liming Cai, Ann Derleth

UW Biostatistics Working Paper Series

Objective: To compare performance of one-time health interventions to those that change the probability of transitioning from one health state to another. Study Design and Setting: We used multi-state life table methods to estimate the impact of eight types of interventions on several outcomes. Results: In a cohort beginning at age 65, curing all the sick persons at baseline would increase life expectancy by 0.23 years and increase years of healthy life by .54 years. An equal amount of improvement could be obtained with a 12% decrease in the probability of getting sick, a 16% increase in the probability of …

Tag Snp Selection For Finnish Individuals Based On The Ceph Utah Hapmap Database, Cristen J. Willer, Laura J. Scott, Lori L. Bonnycastle

University Faculty Publications and Creative Works

The pattern and nature of linkage disequilibrium in the human genome is being studied and catalogued as part of the International HapMap Project [2003: Nature 426:789-796]. A key goal of the HapMap Project is to enable identification of tag single nucleotide polymorphisms (SNPs) that capture a substantial portion of common human genetic variability while requiring only a small fraction of SNPs to be genotyped [International HapMap Consortium, 2005: Nature 437:1299-1320]. In the current study, we examined the effectiveness of using the CEU HapMap database to select tag SNPs for a Finnish sample. We selected SNPs in a 17.9-Mb region of …

Gpnn: Power Studies And Applications Of A Neural Network Method For Detecting Gene-Gene Interactions In Studies Of Human Disease, Alison A. Motsinger, Stephen L. Lee, George Mellick, Marylyn D. Ritchie

Dartmouth Scholarship

The identification and characterization of genes that influence the risk of common, complex multifactorial disease primarily through interactions with other genes and environmental factors remains a statistical and computational challenge in genetic epidemiology. We have previously introduced a genetic programming optimized neural network (GPNN) as a method for optimizing the architecture of a neural network to improve the identification of gene combinations associated with disease risk. The goal of this study was to evaluate the power of GPNN for identifying high-order gene-gene interactions. We were also interested in applying GPNN to a real data analysis in Parkinson's disease.

The Role Of Radiation Therapy On Medically Inoperable Clinically Localized Non-Small Cell Lung Patients: London Regional Cancer Program (Lrcp) Clinical Experience, Michael Lee, Edward Yu, Robert Ash, Patricia Tai, Larry Stitt, George Rodrigues, Rashid Dar, Mark Vincent, Richard Inculet, Richard Malthaner

Oncology Presentations

Lung cancer is the most frequent cause of cancer death in both men and women in North America. In 2006, an estimated 22,700 Canadians will be diagnosed with lung cancer and 19,300 will die of it (Canadian Cancer Statistics 2006).

Approximately 15-20% of NSCLC patients present with early or localized disease.

Surgical resection of T1-2N0 NSCLC remains the treatment of choice for this population, and results in a 5-year survival rate of 50-70%.

Patients deemed medically inoperable have been treated with non-surgical therapies, such as radiation therapy(RT), while some patients have simply been observed without any tumor therapy because of …

Cyclosporin Versus Tacrolimus For Liver Transplanted Patients, Elizabeth Haddad, Vivian Mcalister, Elizabeth Renouf, Richard Malthaner, Mette S. Kjaer, Lise Lotte Gluud

Surgery Publications

A systematic review of randomized clinical trials (RCT) was undertaken to evaluate the beneficial and harmful effects of immunosuppression with cyclosporin versus tacrolimus for liver transplanted patients. MEDLINE, EMBASE, Cochrane Central and Hepato-Biliary Group Controlled Trials Registers were searched. Using fixed and random effects model, relative risk (RR), values <1 favoring>tacrolimus, with 95% confidence intervals (CI) were calculated. Of 717 potentially relevant references, 16 RCTs were eligible for inclusion. Mortality and graft loss at 1 year were significantly reduced in tacrolimus-treated recipients (Death: RR 0.85, 95% CI 0.73-0.99; graft loss: RR 0.73, 95% CI 0.61-0.86). Tacrolimus reduced the number of recipients …

Cutaneous And Presumed Visceral Leishmaniasis In A Soldier Deployed To Afghanistan, James P. Woodrow, Joshua D. Hartzell, Jim Czarnik, David Brett-Major, Glenn Wortmann

Journal Articles: Epidemiology

Leishmaniasis has been frequently diagnosed in US military personnel returning from duty in Southwest Asia. The majority of cases have demonstrated cutaneous disease, although a few cases of visceral disease have been documented. We present the case of an immunocompetent, HIV-negative, US Army soldier who suffered both visceral and cutaneous manifestations of leishmaniasis after returning from deployment in Afghanistan. Overlap of cutaneous and visceral involvement is rare and has not been reported in our cohort. Latent Plasmodium vivax infection may have been an exacerbating cofactor. We discuss this case and present a review of the literature.

Laboratory Diagnosis Of Tuberculosis In Primary Care, David Brett-Major, Thomas E. Walsh

Journal Articles: Epidemiology

No abstract provided.

Need For Cognition And Message Complexity In Motivating Fruit And Vegetable Intake Among Callers To The Cancer Information Service, Pamela Williams-Piehota, Judith Pizarro, Stephanie A. Navarro Silvera, Linda Mowad, Peter Salovey

Department of Public Health Scholarship and Creative Works

This field experiment examined the impact of an individual's need for cognition (NFC; the tendency to enjoy thinking deeply about issues), complex versus simple messages, and the interaction of NFC and message type on encouraging fruit and vegetable consumption. Callers to the Cancer Information Service of the National Cancer Institute (N = 517) were asked to participate in the experiment at the end of their call. Individual NFC was assessed, and participants were assigned randomly to receive a telephone message promoting fruit and vegetable consumption that was either complex and multifaceted or simple and straightforward. Similarly constructed brochures were mailed …

Lack Of Knowledge Of Mother-To-Child Transmission In Kenya Among Women Ages 15-49, Nisha Warrier

Theses and Dissertations

Purpose: The epidemic of mother-to-child transmission (MTCT) of HIV/AIDS in resource-poor countries is dramatic; it is responsible for nearly 90% of childhood infections. The primary purpose of analysis was to understand the distribution of factors and their association with lack of knowledge of MTCT in Kenya. In parallel, another aim was to identify the relationship between media, particularly frequency of radio exposure, and lack of knowledge.Methods: This study used the 2003 Kenya Demographic and Health Survey (DHS) collected for 8,195 women, ages 15-49. Descriptive analysis, univariate analysis, and logistic regression were completed on SPSS 14 software.Results: In the sample, 1151 …

Factors Associated With High Sexual Risk Behavior In Single Women, Thomas B. M. Leecost

Theses and Dissertations

Objective: This study was to identify factors associated with High Sexual Risk Behavior (HSRB) in single Afro American women seen in an Epidemiology/Sexual transmitted disease (EPID/STD) Clinic in Richmond, Virginia from January 2006 through April 2006.Method: Participants were 154 single women (no history of marriage) between the ages of 18-30 visiting the EPID/STD clinic for the first time.Demographic information was obtained from their records. A volunteer interview was given that contained 101 variables to evaluate for High Sexual Risk Behavior (HSRB). HSRB was defined to response 'yes' to the question, "During the past 3 months did you have sex with …

Determinants Of Dating Violence Among Youth In The U.S., Candace Hamm

Theses and Dissertations

Background: Physical Dating Violence (PDV) victimization is a major public health concern among adolescents in the United States. Research has shown that determinants of PDV victimization are different for male and female adolescents. However, inconsistent findings entail that further research needs to be done using a representative sample of male and female adolescents.Objective: To identify gender-specific determinants of PDV victimization utilizing a nationally representative sample of high school adolescents.Methods: Data from the 2005 National Youth Risk Behavior Survey was used for this analysis. The study population included 6.951 male and 6,807 female students in grades 9 through 12. Bivariate and …

The Association Between Breast Feeding And Being Overweight In Children, Naja Jamil Eldanaf

Theses and Dissertations

Purpose: Obesity/Overweight in children is an epidemic and the most common disorder of childhood in the developed world. Prevalence is increasing, leading to short- and long-term complications. Breastfeeding may protect against childhood obesity, but the debate is ongoing. The main purpose of this project was to assess the relationship between breastfeeding and being overweight in early childhood.Methods: Data were collected from the State and Local Area Integrated Telephone survey; National Survey of Children's Health, 2003. Overall, 16,358 children, ages 3 to 5, were included in the sample. SPSS Complex Sample software was utilized to generate for all analyses. Complex samples …

Machismo As A Determinant For Hiv/Std Risk Behavior Among Latino Msm, Jacqueline L. Sears

Theses and Dissertations

Objective: Male-to-male sexual contact is the most common mode of transmission for HIV among Latino men. Psychosocial factors such as machismo, homophobic discrimination, and internalized homophobia have been hypothesized to greatly impact sexual behaviors among Latinos. However, studies investigating the relationship between these psychosocial factors and risky sexual behaviors are limited. This study examined the impact of machismo on risky sexual behaviors among Latino Male who have Sex with Men (MSM).Methods: This study utilized data collected from 254 Latino MSM in 1999 from selected cities within Virginia. The analysis focused on respondent demographic characteristics, psychosocial factors, acculturation, and sexual risky …

Association Between Smoking, Chemical Exposure And Hearing Loss In An Occupational Setting, Darlene W. Olive

Theses and Dissertations

Objective: Twenty-two million Americans or roughly 8% of the population are hearing impaired. This affects more than just the ability for one to hear. In the last three decades, younger Americans have shown a sharp increase in hearing impairment. Hearing loss affects social and emotional well being and thus has the ability to decrease one's quality of life. This study was designed to examine the association between smoking, workplace chemical exposure, and hearing loss.Methods: This cross-sectional population-based study was conducted in an occupational health clinic setting in Virginia. The study population consisted of employees from local businesses who visited the …

A Needs Assessment For Annual Physical Examination For Selected Richmond Public School Children, Aimee Gibbs

Theses and Dissertations

Introduction: The following risk factors have found to be associated with inadequate health care and have been found to affect the well-being of children: racial or ethnic minority, poverty status, median family income, family structure of household, maternal education level, and parental employment status. Also, there has found to be health indicators including, teen pregnancy, asthma hospitalization, and lead poisoning cases that affect the well-being of a child and are associated with the presence of these risk factors in a population. Objectives: The objectives of this study is to (1) compare the presence of risk factors and health indicators in …