Theses - Honors College
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Browsing Theses - Honors College by Author "Abell, Troy D."
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Item Comparative Effectiveness of Autologous Platelet Gel in Coronary Artery Bypass Grafting Surgery: A Formal Decision Analysis(2012-05-07) Cooper, Jacob; Abell, Troy D.; Economics.; Baylor University.; Lisa Baker; Carmichael, Michael; Honors College.Coronary artery bypass grafting (CABG) surgery is one of the most common operations performed in the United States. Despite the frequency of this operation, however, it is estimated that surgical site infections (SSIs) occur with a cumulative incidence between 0.5%-7% among CABG patients. In a time of increasing pressure for health care to improve in quality, hospitals must prevent such infections or risk being required to pay for the expenses incurred to treat those infections that arise. Autologous Platelet Gel (APG) has presented itself as an effective method by which to prevent SSIs through the escalation of the immunological response and the growth of new tissue. This decision analysis aims to answer the clinical question: Should Autologous Platelet Gel be used in Coronary Artery Bypass Grafting procedures along with the current standard of care (SOC)? A decision analytic model was used to determine the total expected mortality that is produced from the use of the standard of care (SOC) alone and the SOC along with APG, giving respect to (a) severity of the SSI; (b) development of deep SSI from a superficial SSI; (c) surgical revision of the SSI; and (d) the cause of mortality.Item A Cross-Sectional Study of the Effects of Stressors Upon Blood Glucose Levels in Non-Obese Patients in Rural Western Kenya(2012-05-09) Rogalla, Aislinn; Abell, Troy D.; Biology.; Baylor University.; Honors College.In order to more effectively address the expansion of type 2 diabetes worldwide, this study investigated the role that stressors and the stress response play in the development of diabetes. This study analyzed clinical data collected from a sample population of 685 subjects of Luo ethnicity who attended a clinic in May, 2010, in rural western Kenya. Stressors were self-reported by the patients, and blood glucose levels were determined from blood samples. Diabetes, measured as blood glucose levels over 200 mg/dL, was found to be unrelated to body mass index, an accepted measure for obesity (X^2 = 2.51, df = 5, p = 0.7753).Item The Effect of Age and Gender on the Prevalence and Severity of Hypertension in Rural Western Kenya(2013-05-24) Sok, Monica; Baker, Lisa; Biology.; Baylor University.; Abell, Troy D.; Honors College.In order to effectively lessen the drastically increasing morbidity of hypertension in sub-Saharan Africa, new prevalences must be calculated and the causes and aggravating factors of this disease must be more completely understood in this region. The literature repeatedly states how prevalence tends to be underestimated in this area of the world due to lack of blood pressure measurements and the highlighted focus on infectious diseases. Many studies have presented different, solid evidence on potential causes behind hypertension including the common ones of BMI, age, diet, and level of physical activity. The usual sample sizes have focused on older groups. The literature lacks concrete data concerning the nature of high blood pressure in younger groups. This cross-sectional study analyzes previously collected clinical data from a sample population of 685 patients who attended a clinic in May 2010 in rural western Kenya within the Nyando District. Data trends are inferred from blood pressure measurements, anthropometric measurements, blood samples, and the patient’s self-report of symptoms. After creating the cut-off age of 18 years, the study’s sample size reduced to 321 patients. For those between the ages of 18 and 44, the prevalence of high systolic blood pressure is 19.42%. For those equal to or over the age of 45, the prevalence of high systolic blood pressure is 53.50%. The prevalence of high blood pressure in males is 43.59% and the prevalence in females is 35.48%. BMI is found to be a statistically significant predictor of the severity and presence of high blood pressure only in the young group and the female group. These results show that hypertension is a silent, severe, proliferating problem in the rural area. The pathophysiology behind high blood pressure is typical in the female group, but there is clearly a different physiological process creating hypertension in those who are young and those who are thin.Item The Effect of Maternal Fat Specialization on Infant Birthweight(2012-05-02) Frensley, Alexandra; Abell, Troy D.; University Scholars - Honors Program; Honors College.In order to maximize the number of infants weighing in the birthweight range associated with the lowest amount of morbidity and mortality (2,500-4,000 grams) the complex interactions between the anthropometric, social, and environmental factors that influence birthweight need to be better understood. Currently, maternal gestational weight gain recommendations are based on body mass index (BMI). However, BMI is a measurement of total maternal adiposity and does not account for fat specialization during pregnancy. It is hypothesized that upper body maternal fat stores are used to fuel fetal growth during pregnancy whereas thigh fat stores are reserved for lactation. Therefore, it is expected that maternal pre-pregnancy upper body fat will correlate with infant birthweight and lower body fat stores will not. This NIH-funded prospective cohort study follows 1,206 mother-infant pairs from first prenatal visit to after delivery with the objective of investigating the impact of maternal height, pre-pregnancy fat distribution, and gestational weight gain on infant birthweight. When birthweight was regressed on traditional determinants of birthweight (gestational age, sex of the infant, parity of the mother, maternal ethnicity, and smoking status) and maternal height, maternal gestational weight gain, circumference of the forearm at the beginning of pregnancy, and subscapular skinfold measurement at the beginning of pregnancy, 0.5423 of the variance in infant birthweight was explained (p = 0 .0001). Thigh adiposity was not associated with infant birthweight (p = 0.9819) and did not add to the explained variance. These results indicate that upper body fat directly contributes to fetal growth during pregnancy, with infant birthweight being independent of pre-pregnancy lower body fat stores. This is consistent with the growing body of knowledge that lower body fat stores primarily are used for lactation.Item The Effects of Family Functioning on Birthweight: a Prospective Cohort Study(2013-05-24) Bonow, Michael; Abell, Troy D.; University Scholars.; Baylor University.; Honors College.A variety of factors influence how the infant grows while in the womb. This NIH-funded prospective cohort study followed 1,206 mother-infant pairs from their first prenatal care visit to delivery. The focus was on the impact of one psychosocial factor, family functioning, on infant birthweight. The hypothesis was that family dysfunction would lead to infants that weighed less, on average, at delivery, than infants born to women from functional families. After a basic linear regression model was built that included the major known determinants of infant birthweight – length of gestation, sex of the infant, parity, maternal height, maternal weight, ethnicity, smoking status, and gestational weight gain – with an adjusted r-squared = 0.5562, the family functioning variable was added. The study found that family functioning was not associated with infant birthweight, with the incremental adjusted r-squared = -0.0071 (p-value = 0.6870) for the family functioning variable.Item The Impact of Nutrition and Body Mass Index on Malaria in Rural Western Kenya(2012-05-08) Godana, Ivy; Baker, Lisa; Biology.; Abell, Troy D.; Honors College.In order to alleviate the burden of malaria in sub-Saharan Africa it is important to understand the impact of lifestyle variables for public health efforts to be effective at the level of the household. This cross-sectional study analyzes clinical data collected from a sample population of 480 patients from the Luo tribe who attended a clinic in May 2011 in rural western Kenya. Data trends are inferred from the patient’s physical examination, and a food questionnaire detailing the daily diet of the patient. The average age in this sample was 34.66 years; the average BMI was 20.05 kg/m2 and the prevalence of malaria was approximately 8.5%. Data indicates that among those who had the most diverse daily diet, only 5% had malaria, while 9% of those who did not eat a daily diverse diet had malaria. Patients with a severely thin Body Mass Index (BMI) were found to be at a higher risk (12.8%) of having malaria, whereas the pre-obese and obese had no (0%) malaria. Data also indicated that with the average prevalence of worms being 7% in the sample, the severely thin manifested a proportion of 17%, with the pre-obese and obese manifesting no diagnoses of worms. Thus, for the patients who consume the most diverse diet, the presence of worms decreases their BMI, increasing the chances of suffering from malaria. Overall, these results show that nutrition and BMI are clinically important tools for combating malaria; however the presence of worms adversely affects the association.Item Prevalence, Severity, and Potential Risk Factors for Fibromyalgia in Rural Western Kenya(2014-05-01) Nguyen, Vivian; Baker, Lisa; Neuroscience.; Baylor University.; Straw to Bread.; Jonathan Tingle.; Abell, Troy D.; Honors College.Past studies in the United States and Canada have found that the prevalence for fibromyalgia (FM) is approximately 2%, but there are very few studies of this condition in developing countries. With the organic basis unknown, the diagnosis of FM rests on the subjective report of chronic pain, sleep and cognitive disturbances, and mood alteration. Since these experiences are partially culturally conditioned, it is possible that the prevalence of FM in a setting of high disease burden, drought, and famine may be different both for physiological and cultural reasons than in a developed country. The prevalence, severity, and factors associated with FM were investigated. A cross-sectional study of 128 Luo adults in rural Kenya consisted of interviews with patients presenting to an annual temporary clinic. A modified version of the 2010 American College of Rheumatology preliminary diagnostic criteria for FM was used to identify bodily points of pain and severity of symptoms in order to categorize subjects with FM. A Community Health Assessment Profile was used to record patient demographic and background information. The study yielded a prevalence of 20% for FM, and the significantly associated factors included age, education, malaria, stroke, and death of a family member. The high prevalence of fibromyalgia in this clinical sample raises questions about the role of increased physical and psychosocial stress in a developing country as a significant context in understanding the disease.Item Race-and-Sex-Specific Modeling of Infant Mortality: An Empirical Analysis of U.S. National Linked Birth/Death DataHoy, Gregory E.; Abell, Troy D.; University Scholars.; Baylor University.; Honors College.The primary objective of the study of fetal growth and development has been to reduce fetal and infant mortality, including the elimination of excess mortality that is observed in certain race/sex groups (i.e. African American and male infants). To continue this effort, this study utilized national infant birth/death data in three ways: (1) Race-and-sex-specific models of infant mortality were developed that corroborated several current hypotheses regarding mortality differences among race/sex groups as well as generated new hypotheses to explain these differences; (2) Eight different models of infant mortality based on infant birthweight and gestational age were created and compared as to predictive ability; and, (3) These eight models allowed for the generation of ‘mortality risk scores’ that will enable clinicians and researchers to study predictors of infant mortality in clinical studies that previously have been two small to adequately estimate infant death.Item Sensitivity and Specificity of Malignant Melanoma, Squamous Cell Carcinoma, and Basal Cell Carcinoma in a General Dermatological Practice(2012-04-26) Taylor, Rachel; Abell, Troy D.; University Scholars.; Honors College.Introduction. Incidence of melanoma and non-melanoma skin cancer is increasing worldwide. Melanoma is the sixth most common cancer in the United States, making skin cancer a significant public health issue. Background and goal. The goal of this study was to provide estimates for sensitivity (P(T+|D+)), specificity (P(T-|D-)), and likelihood ratios (P(T+|D+)/P(T+|D-)) for a positive test and (P(T-|D+)/P(T-|D-)) for negative test of clinical diagnosis compared with pathology reports for malignant melanoma (MM), squamous cell carcinoma (SCC) , basal cell carcinoma (BCC), and benign lesions. This retrospective cohort study collected data on 595 patients with 2,973 lesions in a Central Texas dermatology clinic, randomly selecting patients seen by the dermatology clinic between 1995 and 2011. The ascertation of disease was documented on the pathology report and served as the “gold standard.” Hypotheses. Major hypotheses were that the percentage of agreement beyond that expected by chance between the clinicians’ diagnosis and the pathological gold standard were 0.10, 0.10, 0.30, and 0.40 for MM, SCC, BCC and benign lesions respectively. Results. For MM, the resulting estimates were: (a) 0.1739 (95% C.I. 0.0495, 0.3878), for sensitivity; (b) 0.9952 (95% C.I. 0.9920, 0.9974) for specificity; and (c) the likelihood ratios for a positive and negative test result were 36.23 and 0.83, respectively. For SCC, the resulting estimates were (a) 0.0833 (95% C.I. 0.0312, 0.1726) for sensitivity; (b) 0.9976 (95% C.I. 0.9950, 0.9990); and (c) the likelihood ratios for a positive and negative test result were 34.71 and 0.92, respectively. For BCC, the resulting estimates were: (a) 0.2178 (95% C.I. 0.1630, 0.2812) for sensitivity; (b) 0.9910 (95% C.I. 0.9867, 0.9941) for specificity; and (c) the likelihood ratios for a positive and negative test result were 24.20 and 0.79, respectively. For benign lesions, the resulting estimates were (a) 0.4942 (95% C.I. 0.4715, 0.5169) for sensitivity; (b) 0.9305 (95% C.I. 0.9135, 0.9450) for specificity; and (c) the likelihood ratios for a positive and negative test result were 7.11 and 0.54, respectively. Estimates for the kappa statistic (95% confidence intervals) were 0.1896 (0.0261, 0.3532), 0.1898 (0.0899, 0.2896), 0.3308 (0.2608, 0.3532), and 0.3585 (0.3319, 0.3850) for MM, SCC, BCC, and benign lesions, respectively. Conclusions. Over-biopsying lesions and fear of missing malignancy have a significant impact on the sensitivity and specificity of clinical diagnosis, leading to lowered accuracy. These results challenge clinicians to continue to work toward improving their diagnostic skills concerning MM, SCC, BCC, and benign lesions.Item A Study of Hunger, BMI, and the Occurrence of Infectious Disease in Rural Western Kenya(2012-05-01) Hammond, Molly; Baker, Lisa; Biology.; Department of Biology; Baylor University.; Abell, Troy D.; Honors College.The purpose of this study was to determine the state of food insecurity in a poverty-stricken community in western Kenya using a hunger scale questionnaire (HSQ) to investigate the three-fold relationship between food insecurity, body mass index (BMI), and infectious disease. This cross-sectional study analyzed data from a clinical sample of 480 patients of the Luo ethnicity who completed the HSQ in May 2011. The results showed that 94.37% of patients were designated as food-insecure, while merely 5.63% were food-secure. Out of the 187 cases of infectious disease, 180 cases were found in food-insecure patients (92.26%). Of the 6.88% of patients who had worms, none were food-secure. The most striking finding was the association between food insecurity, age, and BMI: 51.20% of food-insecure youths had BMIs within the severely thin range, compared to only 3.73% of food-insecure adults. The majority of adults, regardless of food insecurity, had BMIs concentrated in the normal range (p = <.0001). In addition to determining the severity of the hunger crisis in this community, these findings demonstrate the susceptibility of youth to food insecurity’s threatening consequences: low BMI. This study adds support for the use of the HSQ as an effective predictor for BMI and for continued research investigating the potential role of the HSQ as a determinant of the occurrence of infectious disease.