Epidemiology Commons^™

Estimating Causal Parameters In Marginal Structural Models With Unmeasured Confounders Using Instrumental Variables, Tanya A. Henneman, Mark Johannes Van Der Laan, Alan E. Hubbard

U.C. Berkeley Division of Biostatistics Working Paper Series

For statisticians analyzing medical data, a significant problem in determining the causal effect of a treatment on a particular outcome of interest, is how to control for unmeasured confounders. Techniques using instrumental variables (IV) have been developed to estimate causal parameters in the presence of unmeasured confounders. In this paper we apply IV methods to both linear and non-linear marginal structural models. We study a specific class of generalized estimating equations that is appropriate to these data, and compare the performance of the resulting estimator to the standard IV method, a two-stage least squares procedure. Our results are applied to …

The Role Of Diet And Physical Activity For Ovarian Cancer Results From The Adventist Health Study, Fatemeh Kiani

Loma Linda University Electronic Theses, Dissertations & Projects

A few aspects of the epidemiology of ovarian cancer are well understood, such as the inverse relationship with parity and oral contraceptive (OC) use. The role of other factors such as the potential influence of diet or physical activity is far from being established. A few studies, however, have been able to identify dietary risk factors for ovarian cancer. In this dissertation, I have conducted two studies that investigate the relationship between dietary factors and physical activity and the three endpoints: 1) nonfatal ovarian cancer (1976-1982; time to diagnosis), 2) fatal ovarian cancer (1976-1988; time to death), and 3) total …

Body Weight And Mortality Among Adults Who Never Smoked, Pramil N. Singh

Loma Linda University Electronic Theses, Dissertations & Projects

Most prospective studies identify an increased mortality risk for adults of high body mass index (> 27 kg/m²) that is commonly attributed to the effects of excess body fat, and also identify an increased mortality risk for adults of low body mass index (< 21 kg/m²), an association that, if causal among healthy adults, is without adequate pathophysiologic support.

In this dissertation, I have conducted three studies that continue the investigation of adiposity in relation to mortality among never-smoking adults of the California Seventh-day Adventist population. Among never-smoking adults of the Adventist Mortality Study (1960-1985), the relation between …

Assessing The Accuracy Of A New Diagnostic Test When A Gold Standard Does Not Exist, Todd A. Alonzo, Margaret S. Pepe

UW Biostatistics Working Paper Series

Often the accuracy of a new diagnostic test must be assessed when a perfect gold standard does not exist. Use of an imperfect test biases the accuracy estimates of the new test. This paper reviews existing approaches to this problem including discrepant resolution and latent class analysis. Deficiencies with these approaches are identified. A new approach is proposed that combines the results of several imperfect reference tests to define a better reference standard. We call this the composite reference standard (CRS). Using the CRS, accuracy can be assessed using multistage sampling designs. Maximum likelihood estimates of accuracy and expressions for …

A Longitudinal Study Of Hospitalization Rates For Patients With Chronic Disease: Results From The Medical Outcomes Study., Eugene C. Nelson, Colleen A. Mchorney, Willard G. Manning, W H. Rogers

Dartmouth Scholarship

To prospectively compare inpatient and outpatient utilization rates between prepaid (PPD) and fee-for-service (FFS) insurance coverage for patients with chronic disease. Data from the Medical Outcomes Study, a longitudinal observational study of chronic disease patients conducted in Boston, Chicago, and Los Angeles.A four-year prospective study of resource utilization among 1,681 patients under treatment for hypertension, diabetes, myocardial infarction, or congestive heart failure in the practices of 367 clinicians.

Student Evaluations Of Teaching Effectiveness: The Interpretation Of Observational Data And The Principle Of Faute De Mieux, B. Burt Gerstman

Faculty Publications

Student opinion surveys are important but widely misunderstood tools for evaluating teaching effectiveness. In this brief review, an analogy is drawn between the use and interpretation of observational data for public health and biomedical research and the use of student opinion data in evaluating teach ing effectiveness. Sources of systematic error in the form of selection bias, information bias, and confounding are defined and illustrated. Original data concerning intermittent "quid pro quo" confounding (i.e., the effect of expected grades on student evaluations of teaching) are presented. Finally, the principle of faute de mieux ("lack of anything better") and the interpretation …

Diet And Colon Cancer Risk In The Population Of Thailand, Nithat Sirichotiratana

Loma Linda University Electronic Theses, Dissertations & Projects

Epidemiological studies have emphasized environmental influences, especially a diet high in animal fat and low in fiber, as major risk factors for colon cancer. In order to examine the relationship between dietary fat and fiber and occurrence of colon cancer, patient medical records from the National Cancer Institute between 1981-1991 were used for the first hospital-based case-control study of diet and colon cancer in Thailand. These records included a total of 168 cases and 357 controls. Data on the frequency consumption of various food items were obtained by using an existing food frequency questionnaire, completed as part of patient’s history …

Preliminary Epidemiological Interpretation Of The Intrinsic And Extrinsic Factors Contributing To The Coverage And Participation Rates Of The Vaccination Program In Arssi, Ethiopia, Muchie Kidanu

Electronic Theses and Dissertations

Many immunization programs in developing countries arr now undergoing a period of rapid utilization. Innovative strategies, such as immunization holidays, are being tried. Political commitment and enthusiasm are high. There is a strong desire by health professionals to protect the lives of many children from the untimely death and/or disability resulting from infectious diseases preventable by vaccination.

Evaluation of an immunization program can benefit other elements of the health system, particularly those that are not amenable to objective evaluation as immunization. In this case, immunization can serve as an indicator of the overall performance of the health system. The problems …

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 …

Ua37/30/2 Wku Research Notecards - H Topics, Lowell Harrison

Faculty/Staff Personal Papers

Notecards created by Lowell Harrison while researching his book Western Kentucky University. The cards transcribed are for 108 topics beginning with H ranging from Hail Storm to Hundred Club.

Chronic Respiratory Disease Symptom Effects Of Long-Term Cumulative Exposure To Passive Tobacco Smoke And To Ambient Levels Of Tsp, Oxidants, So2, And No2 In Southern California, Gary L. Euler

Loma Linda University Electronic Theses, Dissertations & Projects

To assess risk of chronic respiratory disease symptoms due to long-term exposure to the ambient levels of TSP, oxidants, SO2 and NO2 in photochemical air pollution, symptoms were ascertained using NHLBI questions on 8,572 Southern California Seventh-day Adventist, nonsmokers, 25 years and older, who lived eleven years or longer in their 1977 residential area. Tobacco smoke, active and passive, and occupational exposures were measured by questionnaires, as well as lifestyle characteristics relative to pollution exposure such as time spent outside and residence history. A pulmonary function feasibility study was done on a subsample of 86 women 50-64 years of age …

Sources Of Nosocomial Infections In Immunocompromised Patients (Letter), B. Burt Gerstman

Faculty Publications

No abstract provided.

Sero-Epidemiology Of Q Fever With Special Reference To Complications In A Hospital Population Of Southern California, Ajit Singh Randhawa

Loma Linda University Electronic Theses, Dissertations & Projects

[Abstract Not Included]