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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

Intimate Partner Violence as a Risk Factor for Incident HIV Infection in Women in Rakai, Uganda

Kouyoumdjian, Fiona G 05 September 2014 (has links)
Background: Intimate partner violence (IPV) is a significant public health problem, which has been associated with HIV infection. Previous studies that assessed IPV and HIV have been limited. Objectives: The primary objective of this study was to quantify the association between IPV and incident HIV infection in women in Rakai, Uganda. Secondary objectives were to explore whether condom use and number of partners in the past year mediate this association, and to identify risk factors for IPV. Methods: Data were collected over seven rounds of the Rakai Community Cohort Study between 2000 and 2009. Sexually active women aged 15 to 49 were included in analyses. Longitudinal data analysis was used to quantify the association between IPV and incident HIV infection, modelling participants as random effects. The adjusted population attributable risk fraction was calculated using an adjusted relative risk from a Poisson model. Putative mediators were assessed using Baron and Kenny’s criteria and the Sobel-Goodman test. Longitudinal and non-longitudinal analyses were used to assess predictors of IPV. Results: Women who experienced IPV ever had an odds ratio of incident HIV infection of 1.54 (95% CI 1.14, 2.09, p value 0.01), compared with women who had never experienced IPV. The adjusted population attributable risk fraction of incident HIV during the study period attributable to IPV ever was 14.3% (95% CI 2.8, 23.6). There was no evidence that condom use or partner violence in the past year mediated the relationship between IPV and HIV. Risk factors for IPV included sexual abuse, younger age at first sex, lower levels of education, forced first sex, younger age, being married, relationship of shorter duration, alcohol use by women and by their partners, and thinking that violence is acceptable. Discussion: This study demonstrates that IPV is associated with incident HIV infection in a population-based cohort in Uganda, although the population attributable risk fraction was modest. The prevention of IPV both in early sexual experiences and in adulthood should be a public health priority, and could contribute to HIV prevention. Further research is needed to understand the pathway from IPV to HIV infection.
2

The Relationship Between Temperature and 911 Medical Dispatch Data for Heat-Related Illness in Toronto, 2002-2005: An Application of Syndromic Surveillance

Bassil, Katherine 26 February 2009 (has links)
Heat-related illness (HRI) is of growing public health importance, particularly with climate change and an anticipated increased frequency of heat waves. A syndromic surveillance system for HRI could provide new information on the population impact of excessive heat and thus be of value for public health planning. This study describes the association between 911 medical dispatch calls for HRI and temperature in Toronto, Ontario during the summers of 2002-2005. A combination of methodological approaches was used to understand both the temporal trend and spatial pattern in the relationship between 911 medical dispatch data and temperature. A case definition for HRI was developed using clinical and empirical assessments. Generalized Additive Models (GAM) and Zero inflated Poisson regression (ZIP) were used to determine the association between 911 calls and mean and maximum temperature. The validity of the HRI case definition was investigated by making comparisons with emergency department visits for HRI. Descriptive, aberration detection, and cross-correlation methods were applied to explore the timing and volume of HRI calls in relation to these visits, and the declaration of heat alerts. Finally, the existence of neighbourhood level spatial variation in 911 calls for HRI was analyzed using geospatial methods. This is the first study to demonstrate an association between daily 911 medical dispatch calls specifically for HRI and temperature. On average, 911 calls for HRI increased up to a maximum of 36% (p<.0001) (median 29%) for each 1°C increase in temperature. The temporal trend of 911 calls for HRI was similar to emergency department visits for HRI and heat alerts, improving confidence in the validity of this data source. Heterogeneity in the spatial pattern of calls across neighbourhoods was also apparent, with recreational areas near the waterfront demonstrating the highest percentage increase in calls. Monitoring 911 medical dispatch data for HRI could assist public health units carrying out both temporal and geospatial surveillance, particularly in areas where synoptic based mortality prediction algorithms are not being utilized. This previously untapped data source should be further explored for its applications in understanding the relationship between heat and human health and more appropriately targeting public health interventions.
3

Vascular and Metabolic Risk Factors, Carotid Atherosclerosis and Vascular Cognitive Impairment in a First Nations Population

Fergenbaum, Jennifer 03 March 2010 (has links)
The objectives of the thesis were to examine the associations between vascular and metabolic risk factors, carotid atherosclerosis and cognitive function in a Canadian First Nations population. Eligible individuals were ≥18 years and with First Nations status who had undergone cognitive function assessment by the Clock Drawing Test (CDT) and the Trail Making Test Parts A and B. Parts A and B were combined into an executive function score (TMT-exec). Anthropometric, vascular and metabolic risk factors were assessed by interview, clinical examinations and blood tests. Doppler ultrasonography assessed carotid atherosclerosis (carotid stenosis, plaque volume). For the 190 individuals with TMT-exec scores, obese individuals were at a 4-fold increased risk for lowered cognitive performance compared to those who were not obese (odds ratio [OR]: 3.77, 95% confidence interval [CI]: 1.46-9.72). Those having an increased waist circumference also had 5 times the risk compared to those without an increased waist circumference (OR: 5.41, 95% CI: 1.83-15.99). Individuals having the metabolic syndrome were at a 4-fold increased risk compared to those without the metabolic syndrome (OR: 3.67, 95% CI: 1.34-10.07). No other cardiovascular risk factors were associated and no associations were shown for the CDT. For TMT-exec only, individuals with elevated levels of left (LCS) and total carotid stenosis (TCS) were less likely to demonstrate lowered cognitive performance (LCS, OR: 0.47, 95% CI: 0.24-0.96; TCS, OR: 0.40, 95% CI: 0.20-0.80). In structural equation modeling, for every 1-unit change in the anthropometric factor in kg/m2, there was a 0.86-fold decrease in the percent of TCS (p<0.05). The etiology of VCI is vascular and is affected by non-traditional risk factors such as obesity. The health effects of obesity beyond traditional disease endpoints warrants further study. Mild-moderate levels of carotid stenosis are not detrimental to cognitive functioning and may additionally include acting as a mediator.
4

The Relationship Between Temperature and 911 Medical Dispatch Data for Heat-Related Illness in Toronto, 2002-2005: An Application of Syndromic Surveillance

Bassil, Katherine 26 February 2009 (has links)
Heat-related illness (HRI) is of growing public health importance, particularly with climate change and an anticipated increased frequency of heat waves. A syndromic surveillance system for HRI could provide new information on the population impact of excessive heat and thus be of value for public health planning. This study describes the association between 911 medical dispatch calls for HRI and temperature in Toronto, Ontario during the summers of 2002-2005. A combination of methodological approaches was used to understand both the temporal trend and spatial pattern in the relationship between 911 medical dispatch data and temperature. A case definition for HRI was developed using clinical and empirical assessments. Generalized Additive Models (GAM) and Zero inflated Poisson regression (ZIP) were used to determine the association between 911 calls and mean and maximum temperature. The validity of the HRI case definition was investigated by making comparisons with emergency department visits for HRI. Descriptive, aberration detection, and cross-correlation methods were applied to explore the timing and volume of HRI calls in relation to these visits, and the declaration of heat alerts. Finally, the existence of neighbourhood level spatial variation in 911 calls for HRI was analyzed using geospatial methods. This is the first study to demonstrate an association between daily 911 medical dispatch calls specifically for HRI and temperature. On average, 911 calls for HRI increased up to a maximum of 36% (p<.0001) (median 29%) for each 1°C increase in temperature. The temporal trend of 911 calls for HRI was similar to emergency department visits for HRI and heat alerts, improving confidence in the validity of this data source. Heterogeneity in the spatial pattern of calls across neighbourhoods was also apparent, with recreational areas near the waterfront demonstrating the highest percentage increase in calls. Monitoring 911 medical dispatch data for HRI could assist public health units carrying out both temporal and geospatial surveillance, particularly in areas where synoptic based mortality prediction algorithms are not being utilized. This previously untapped data source should be further explored for its applications in understanding the relationship between heat and human health and more appropriately targeting public health interventions.
5

Vascular and Metabolic Risk Factors, Carotid Atherosclerosis and Vascular Cognitive Impairment in a First Nations Population

Fergenbaum, Jennifer 03 March 2010 (has links)
The objectives of the thesis were to examine the associations between vascular and metabolic risk factors, carotid atherosclerosis and cognitive function in a Canadian First Nations population. Eligible individuals were ≥18 years and with First Nations status who had undergone cognitive function assessment by the Clock Drawing Test (CDT) and the Trail Making Test Parts A and B. Parts A and B were combined into an executive function score (TMT-exec). Anthropometric, vascular and metabolic risk factors were assessed by interview, clinical examinations and blood tests. Doppler ultrasonography assessed carotid atherosclerosis (carotid stenosis, plaque volume). For the 190 individuals with TMT-exec scores, obese individuals were at a 4-fold increased risk for lowered cognitive performance compared to those who were not obese (odds ratio [OR]: 3.77, 95% confidence interval [CI]: 1.46-9.72). Those having an increased waist circumference also had 5 times the risk compared to those without an increased waist circumference (OR: 5.41, 95% CI: 1.83-15.99). Individuals having the metabolic syndrome were at a 4-fold increased risk compared to those without the metabolic syndrome (OR: 3.67, 95% CI: 1.34-10.07). No other cardiovascular risk factors were associated and no associations were shown for the CDT. For TMT-exec only, individuals with elevated levels of left (LCS) and total carotid stenosis (TCS) were less likely to demonstrate lowered cognitive performance (LCS, OR: 0.47, 95% CI: 0.24-0.96; TCS, OR: 0.40, 95% CI: 0.20-0.80). In structural equation modeling, for every 1-unit change in the anthropometric factor in kg/m2, there was a 0.86-fold decrease in the percent of TCS (p<0.05). The etiology of VCI is vascular and is affected by non-traditional risk factors such as obesity. The health effects of obesity beyond traditional disease endpoints warrants further study. Mild-moderate levels of carotid stenosis are not detrimental to cognitive functioning and may additionally include acting as a mediator.
6

Complications following Total Joint Arthroplasty in Patients with Rheumatoid Arthritis

Ravi, Bheeshma 14 January 2014 (has links)
Background: Total joint arthroplasty (TJA) is indicated in persons with end-stage arthritis of the hip and knee (THA and TKA, respectively). While most TJAs are performed for osteoarthritis (OA), 3%-13% are performed in patients with rheumatoid arthritis (RA). Most of the evidence regarding complications following TJA is based on studies of patients with OA, with little known about recipients with RA. The purpose of this thesis was to summarize current evidence on the rates of complications following TJA in patients with RA, to quantify this risk using validated methods, and to determine the impact of surgeon experience performing TJA in persons with RA on this risk. Methods: For reports published between 1990 and 2011, we evaluated the evidence regarding the risk of complications following TJA in RA using qualitative and quantitative methods. In a cohort of recipients of primary elective THA or TKA between 2002 and 2009, in Ontario, Canada, we identified patients with RA using a validated algorithm. Multivariable Cox proportional hazards regression was used to evaluate the relationship between arthritis type (RA, OA, other) and the occurrence of surgical complications, and to evaluate the impact of surgeon experience on the risk of a complication. Results: Forty published studies were reviewed. Relative to TJA recipients with OA, those with RA were at increased risk of dislocation following THA, and increased risk for joint infection following TKA. These findings were confirmed in our cohort study: adjusted hazard ratio (HR) for dislocation 1.91, p=0.001; adjusted HR for infection 1.47, p=0.03). In TJA recipients with RA, greater surgeon RA volume was associated with a reduced risk for surgical complications (adjusted HR per 10 additional cases: 0.81, p=0.002). Conclusions: In a population-based cohort of primary elective TJA recipients, patients with RA were at significantly increased risk for dislocation following THA and joint infection following TKA. Increased surgeon experience performing TJA in patients with RA attenuated the risk for surgical complications among TJA recipients with RA. Further research is required to identify the mediators of the increased complication risk in patients with RA, and to delineate strategies to optimize outcomes in these patients.
7

Complications following Total Joint Arthroplasty in Patients with Rheumatoid Arthritis

Ravi, Bheeshma 14 January 2014 (has links)
Background: Total joint arthroplasty (TJA) is indicated in persons with end-stage arthritis of the hip and knee (THA and TKA, respectively). While most TJAs are performed for osteoarthritis (OA), 3%-13% are performed in patients with rheumatoid arthritis (RA). Most of the evidence regarding complications following TJA is based on studies of patients with OA, with little known about recipients with RA. The purpose of this thesis was to summarize current evidence on the rates of complications following TJA in patients with RA, to quantify this risk using validated methods, and to determine the impact of surgeon experience performing TJA in persons with RA on this risk. Methods: For reports published between 1990 and 2011, we evaluated the evidence regarding the risk of complications following TJA in RA using qualitative and quantitative methods. In a cohort of recipients of primary elective THA or TKA between 2002 and 2009, in Ontario, Canada, we identified patients with RA using a validated algorithm. Multivariable Cox proportional hazards regression was used to evaluate the relationship between arthritis type (RA, OA, other) and the occurrence of surgical complications, and to evaluate the impact of surgeon experience on the risk of a complication. Results: Forty published studies were reviewed. Relative to TJA recipients with OA, those with RA were at increased risk of dislocation following THA, and increased risk for joint infection following TKA. These findings were confirmed in our cohort study: adjusted hazard ratio (HR) for dislocation 1.91, p=0.001; adjusted HR for infection 1.47, p=0.03). In TJA recipients with RA, greater surgeon RA volume was associated with a reduced risk for surgical complications (adjusted HR per 10 additional cases: 0.81, p=0.002). Conclusions: In a population-based cohort of primary elective TJA recipients, patients with RA were at significantly increased risk for dislocation following THA and joint infection following TKA. Increased surgeon experience performing TJA in patients with RA attenuated the risk for surgical complications among TJA recipients with RA. Further research is required to identify the mediators of the increased complication risk in patients with RA, and to delineate strategies to optimize outcomes in these patients.
8

A Longitudinal Investigation into the Association of Smoking and Depression among Adolescents: Exposures, Outcomes, and Auxiliary Hypotheses

Chaiton, Michael 05 August 2010 (has links)
Introduction: The association between smoking and depression has been well established, but the nature of the relationship has not been determined. A synthesis of longitudinal studies examining the onset of smoking and depression among adolescents demonstrated consistent evidence of both smoking predicting depression and depression predicting smoking in multiple populations; however, more work is needed to develop and test the mechanisms associated with the onset of the co-occurrence of smoking and depression. This thesis examines the role of a broad range of potential confounders on the relationship between smoking and depression, and investigates a potential mechanism of effect. Method: Analyses were conducted using the Nicotine Dependence in Teens (NDIT) cohort which included 1293 students initially aged 12-13 years recruited from all grade seven classes in a convenience sample of ten secondary schools in Montreal, Canada surveyed twenty times over five years. Multiple regressions were performed to examine the temporal relationship of potential confounders on the relationship between smoking and depression and to empirically observe variables that could be intermediate on pathways between smoking and depression. A growth curve model was developed to test the effect of perceived self medication on changes in depression scores over time. Results: A concept map of the smoking and depression relationship in the NDIT cohort was developed according to the results of proportional hazard and fixed effect regressions in which friend smoking, stress, and anxiety-associated variables were identified as intermediate variables. Perceived self-medication was associated with decelerated rates of change of depressive symptoms over times, suggesting that smoking may increase mean levels of stress and depressive symptoms, but may offer the perception of control. Conclusion: In concert, this thesis suggests a model in which stress and the perceived control of psychobiological function using cigarettes lead to the development of increased depressive symptoms and increased cigarette use.
9

Obesity among Pff-reserve First Nations, Métis, and Inuit Peoples in Canada’s Provinces: Associated Factors and Secular Trends

Ng, Carmina 26 March 2012 (has links)
Aboriginal Canadians (First Nations, Métis, and Inuit) have the highest prevalence of overweight and obesity compared to other ethnic groups in Canada. In order to assess the evolution of the problem over time and to understand potential risk factors, three studies were conducted using nationally-representative survey data. Direct comparisons between Aboriginal and non-Aboriginal Canadians from the same surveys provide important perspectives on the magnitude of health disparities that cannot be obtained by small regional studies that dominate the current available literature. Body mass index (BMI) trajectories from 1994 to 2009 were estimated for Aboriginal and non-Aboriginal Canadians. Aboriginal Canadians experienced higher rates of BMI increase over the 14-year period between 1994 and 2009. Rate of BMI increase was specifically higher for Aboriginal adults born in the 1960s and 1970s when compared with non-Aboriginal adults, and later-born cohorts had consistently higher BMI compared with earlier-born cohorts. The role of potentially modifiable lifestyle factors in obesity among Aboriginal and non-Aboriginal youth was also investigated. Compared to non-Aboriginal youth, consumption of fruits/vegetables and dairy products was lower, and more Aboriginal youth were "high" TV watchers. Physical activity participation did not differ between "high" and "low" TV watchers for both groups, and was associated with lowered odds for obesity only among Aboriginal youth. The complex relationship between obesity and socioeconomic status for Aboriginal and non-Aboriginal Canadians was explored. Employment status was strongly and negatively associated with obesity among Aboriginal men and women. Aboriginal men of high socioeconomic status (SES) were most likely to be obese, whereas Aboriginal women of high SES were least likely to be obese. Important descriptive and analytical information on an emerging and serious public health issue among Aboriginal people in Canada can inform the design and planning of intervention programs and development of public health strategies targeted at obesity.
10

The Role of Chronic Inflammation in the Development of Lung Cancer

Brenner, Darren 10 December 2012 (has links)
Inflammation is believed to play a pivotal role in the development of cancer and in particular lung cancer through both intrinsic and extrinsic pathways. This thesis aimed through 4 manuscripts to determine the role of lung-specific inflammation-related exposures as well as genetic variants (Single Nucleotide Polymorphism (SNPs)) in genes related to inflammation pathways in lung cancer risk. Risk factors of particular interest were lung diseases including emphysema, chronic bronchitis, pneumonia and tuberculosis. Data were collected from a Toronto-based case-control study and combined with data from the International Lung Cancer Consortium (17 studies for the non-genetic analyses and 6 studies for the genetic analyses). For non-genetic data, methods included, but were not limited to, unconditional logistic regression within single studies, Cox proportional hazards regression, meta-analytic techniques and pooled analyses techniques. For genetic data, additive models of association across 7,650 SNPs (selected based on role in inflammation) were pooled across studies and hierarchical modeling iv (HM) was used to incorporate prior functional information from various sources concerning the SNPs of interest. Within the Toronto study (manuscript 1) associations with increased lung cancer risk were observed for occupational exposures, previous lung diseases and a family history of cancer. The meta-analysis (manuscript 2) and pooled analysis (manuscript 3) showed relatively consistent associations between previous lung diseases and lung cancer risk across histology, gender and smoking categories. Results persisted when examining lung disease diagnoses made >10 or >20 years before cancer diagnosis. Our pathway-based analysis of inflammation-related variants and lung cancer risk using HM (manuscript 4) showed that HM is applicable to SNP analysis using pooled designs where heterogeneity can be incorporated into SNP priors. After HM a previously observed variant (rs2736100) and novel variant (rs2741354) were observed to be associated with lung cancer risk at corrected levels and replicated in an independent population. Taken together these results provide further evidence of both intrinsic and extrinsic factors affecting risk of lung cancer through inflammation.

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