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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Secular and Longitudinal Trends in Body Weight in a Large Population of Veterans, 2000-2014

Tamas, Margery J 08 January 2016 (has links)
INTRODUCTION: The prevalence of obesity is increasing in the United States and globally, and impacts many aspects of health. To understand the contribution of body weight to chronic diseases such as diabetes, it is necessary to characterize secular and longitudinal weight trends prior to evaluating the weight effects that may result from medical interventions. The cross-sectional National Health and Nutrition Examination Survey (NHANES) indicates that mean body weight in the adult population increased from 152 lb (69 kg) to 181 lb (82 kg) between 1959 and 2008. However, there are no previously published studies on secular or longitudinal weight trends in a veteran population. OBJECTIVES: The purpose of this study is to describe secular and longitudinal trends in body weight for a large population of male and female individuals with and without diabetes in the Veterans Administration (VA) healthcare system, the largest integrated healthcare system in the United States. METHODS: Retrospective observational analysis of data from VA facilities throughout the United States, in patients who had at least 4 outpatient visits within any consecutive 4-year interval during 2000–2014. The dataset included men and women with and without type 2 diabetes. The primary outcomes were longitudinal trends in body weight stratified by birth cohort, sex, and diabetes status. RESULTS: A total of 4,680,735 unique patients, 1,666,346 with diabetes, were included in the analysis. Regressions were performed on the patient-level data and segmented by birth cohort. A total of 176,034,543 weight observations were included in the analysis, with a median of 15 to 36 weight observations per patient in individuals without diabetes, and a median of 22 to 49 weight observations in individuals with diabetes across birth cohorts. In the year 2000, the y-intercept for the regression equations indicated a mean body weight for men without diabetes of 188 lb (85 kg), for women without diabetes of 166 lb (75 kg), for men with diabetes of 213 lb (97 kg), and for women with diabetes of 195 lb (88 kg). Secular trends in body weight during the study period had median linear increases of 0.53 lb/y (0.24 kg/y) in men with diabetes, 0.50 lb/y (0.23 kg/y) in women with diabetes, 0.53 lb/y (0.24 kg/y) in men without diabetes, and 0.86 lb/y (0.39 kg/y) among women without diabetes, respectively. In cohorts born before 1940, body weight decreased. In the cohorts born between 1940-1949, body weight was stable. In all cohorts born after 1950, body weight increased. Across birth cohorts, the rate of weight increase accelerated from older to younger groups, with higher rates in the groups with diabetes than in the groups without diabetes: β2 = 0.0260 lb2/y (0.01179 kg2/y) in men without diabetes, 0.0398 lb2/y (0.01805 kg2/y) in men with diabetes, 0.0127 lb2/y (0.00576 kg2/y) in women without diabetes, and 0.0895 lb2/y (0.04060 kg2/y) in women with diabetes. CONCLUSIONS: This is the first report of secular and longitudinal weight trends in a large, contemporary veteran population that includes both men and women. Consistent with findings from the Normative Aging Study, a longitudinal study of male veterans from the northeastern United States, weight changes varied from decreases among the oldest birth cohorts to increases in the youngest birth cohorts. Secular changes in body weight by birth cohort were consistent with the patterns reported in the Global Burden of Disease Study. The rate of weight change is accelerated in all younger birth cohorts relative to all older birth cohorts, with the highest rates in women with diabetes. Further analyses of this dataset are recommended to elucidate clinical characteristics associated with longitudinal weight change among individuals with and without diabetes in the veteran population.
2

Genotype and phenotype interactions of the insulin-like growth factor system in type 2 diabetes

Narayanan, Ram January 2013 (has links)
Background: Multiple lines of evidence implicate the insulin-like growth factor(IGF) group of proteins in human type 2 diabetes. The actions of IGF-I and IGF-IIare modulated through their interaction with IGF binding proteins. A holisticapproach to study the IGF system is preferable to analyses of individual proteininteractions as the inter-relationships between these proteins are complex. Inparticular, the associations of IGF-II and its associated binding proteins withcardiovascular risk have been inadequately studied. This study aimed to study indetail the genotype and phenotype interactions of the IGF system with longitudinalcardiovascular risk factor trends and phenotypic outcomes in type 2 diabetes.Methods: 1000 subjects of predominantly Caucasian origin from the SalfordDiabetes Cohort were studied. Measurements of IGF proteins (IGF-I, IGF-II,IGFBP-1, IGFBP-2 and IGFBP-3) were performed in 554 of these patients. 991Caucasian subjects were successfully genotyped for 76 single nucleotidepolymorphisms (SNPs) related to ten genes in the IGF system. In this project weanalysed associations of the studied SNPs with the measured IGF proteins as well aslongitudinal risk factor trends. In addition, the baseline concentrations of themeasured proteins were studied for associations with cardiovascular risk factortrends and vascular outcomes.Results: This project demonstrates for the first time that high serum IGF-IIconcentration at baseline predicts longitudinal increases in high-density lipoproteincholesterol. High baseline IGF-II was also observed to predict longitudinal weightloss. High baseline concentration of IGFBP-2 (which has a preferential associationof IGF-II over IGF-I) was associated with a number of favourable longitudinalcardiovascular risk trends like increased HDL cholesterol and decreased diastolicblood pressure. However high IGFBP-2 was also associated with deterioration inrenal function and increased all-cause and cardiovascular mortality. The IGF2 geneand the genes encoding IGFBP-2 and IGFBP-5 (proteins with IGF-II bindingaffinity) were also associated with longitudinal trends in renal function, bloodpressure and cholesterol concentration.Discussion: This study is the most detailed exploration to date of the genotype andphenotype interactions of the IGF system in a Caucasian population with type 2diabetes. Results from this study strongly hint that changes in IGF-II bioavailabilitymay influence inter-individual variations in cardiovascular risk. The precisebiological role of IGF-II merits clarification in future expression studies in renal,adipose and vascular tissues. Replication of significant results in an independentdiabetes cohort and measurement of other IGF binding proteins will be performed inthe next stage of this study.
3

The rise and fall of mental disorders : an analysis of epidemiological trends

Van der Walt, Merrill Victoria 04 1900 (has links)
Epidemiological trends in mental disorders are shown against a background governed by medical aid health policy. The study quantitatively analyzed a dataset of mental disorders for South Africa’s leading medical aid scheme. South Africa’s leading medical aid scheme has been in operation for almost three decades. This degree of longevity allows for a reliable longitudinal analysis of diagnostic trends. Through consent of the Scheme, a database was provided, which lists mental disorder diagnoses over seven years from 2008 to mid-way through 2015. Data from this source were analyzed and interpreted. Data fields provided and made use of from the raw medical scheme database are: Date of admission (Year, Month); Patient gender; Database population per year; Patient diagnosis (DEG Description); Total per DEG Description. Each diagnosis (mental disorder) is presented in the following ways: 1. Bar charts showing the volume of specific mental illnesses each year. 2. Bar charts showing fluctuations of occurrence of a specific mental illness over time. 3. Frequency of specific mental illnesses over time, relative to the entire database population. 4. Male:Female ratio per mental disorder. 5. Female Outpatient vs. Inpatient volumes across each mental disorder and across all years (2008 – 2015).v 6. Male Outpatient vs. Inpatient volumes across each mental disorder and across all years (2008 – 2015). 7. Total number of patients per mental disorder across time (2008 – 2015). 8. Frequency polygons showing the fluctuation of a selected mental disorder over time as compared to other selected mental disorders. It is found that there are changes in prevalence rates of mental disorders over time and that these fluctuations are attributed to an economic factor within medical aid scheme cost-driven policy. The effect of cost-driven policy is that members diagnosed with a mental disorder may not be granted provision of adequate treatment because diagnosis is in part, determined by economic structures. Costs for mental illness treatment programmes are curtailed by keeping patient numbers significantly low, by radically over-diagnosing certain mental illnesses treated with comparably cheaper pharmaceuticals or by drastically curbing time spent in a mental health facility. Some members of the medical aid scheme have been deliberately misdiagnosed. Alternatively, those, correctly diagnosed, do not receive the treatment required of such an illness. The scenario then is of thousands of mentally ill people, who are not treated effectively. Members continue to pay fees, paying under the illusion that medical cover ensures effective treatment / Psychology / M.A. Psychology

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