No description available.

McMaster University MASTER OF PUBLIC HEALTH (2020) Hamilton, Ontario (Health Research Methods, Evidence, and Impact) TITLE: Applying Machine Learning to Determine Nutrients Predictive of Cardiovascular Disease Using Canadian Linked Population-Based Data AUTHOR: Jason D. Morgenstern, B.Sc. (University of Guelph), M.D. (Western University) SUPERVISOR: Professor L.N. Anderson, NUMBER OF PAGES: xv, 121 / The use of big data and machine learning may help to address some challenges in nutritional epidemiology. The first objective of this thesis was to explore the use of machine learning prediction models in a hypothesis-generating approach to evaluate how detailed dietary features contribute to CVD risk prediction. The second objective was to assess the predictive performance of the models. A population-based retrospective cohort study was conducted using linked Canadian data from 2004 – 2018. Study participants were adults age 20 and older (n=12 130 ) who completed the 2004 Canadian Community Health Survey, Cycle 2.2, Nutrition (CCHS 2.2). Statistics Canada has linked the CCHS 2.2 data to the Discharge Abstracts Database and the Canadian Vital Statistics Death database, which were used to determine cardiovascular outcomes (stroke or ischemic heart disease events or deaths). Conditional inference forests were used to develop models. Then, permutation feature importance (PFI) and accumulated local effects (ALEs) were calculated to explore contributions of nutrients to predicted disease. Supplement-use (median PFI (M)=4.09 x 10-4, IQR=8.25 x 10-7 – 1.11 x 10-3) and caffeine (M=2.79 x 10-4, IQR= -9.11 x 10-5 – 5.86 x 10-4) had the highest median PFIs for nutrition-related features. Supplement-use was associated with decreased predicted risk of CVD (accumulated local effects range (ALER)= -3.02 x 10-4 – 2.76 x 10-4) and caffeine was associated with increased predicted risk (ALER= -9.96 x 10-4 – 0.035). The best-performing model had a logarithmic loss of 0.248. Overall, many non-linear relationships were observed, including threshold, j-shaped, and u-shaped. The results of this exploratory study suggest that applying machine learning to the nutritional epidemiology of CVD, particularly using big datasets, may help elucidate risks and improve predictive models. Given the limited application thus far, work such as this could lead to improvements in public health recommendations and policy related to dietary behaviours. / Thesis / Master of Public Health (MPH) / This work explores the potential for machine learning to improve the study of diet and disease. In chapter 2, opportunities are identified for big data to make diet easier to measure. Also, we highlight how machine learning could find new, complex relationships between diet and disease. In chapter 3, we apply a machine learning algorithm, called conditional inference forests, to a unique Canadian dataset to predict whether people developed strokes or heart attacks. This dataset included responses to a health survey conducted in 2004, where participants’ responses have been linked to administrative databases that record when people go to hospital or die up until 2017. Using these techniques, we identified aspects of nutrition that predicted disease, including caffeine, alcohol, and supplement-use. This work suggests that machine learning may be helpful in our attempts to understand the relationships between diet and health.

Background. A 2012 IOM report is just one of an increasing number of recommendations to incorporate a population health approach into training of all health professionals. In light of the emphasis on and necessity for all future health professionals to possess core public health competences, a medium sized public University incorporated Introduction to Public Health as a required course in their undergraduate, interprofessional Health Sciences curriculum. Purpose. The purpose of this study was to assess the change in core public health competencies of undergraduate Health Sciences students who completed an Introduction to Public Health course. Methods. The Tier 1 Public Health Professionals Competency Assessment was administered in the online Introduction to Public Health courses for undergraduate Health Sciences students; the pretest was administered during the first week and the posttest during the final week of the 15 week course. Purposive sampling was used to assess how the course increased the student’s acquisition of core public health competencies within the designated eight domains. Results. Results of this study showed an increase in the competency scores of the participants from pre to posttest across all of the eight domains. Conclusions. This study demonstrates that an Introduction to Public Health course can increase the core public health competencies of undergraduate Health Sciences students, and the Public Health Professionals Competency Assessment can be used to assess the acquisition of these competencies with and guide curriculum for future health care providers.

My dissertation is composed of an introductory chapter followed by three independent chapters focusing on two themes: health and retirement. The last chapter concludes. After the introductory chapter, the second chapter investigates whether self reported general stress is a mediator in the relationship between socio-economic status (SES) and health. I use a six-year long panel of the Canadian Survey of Labour and Income Dynamics and employ dynamic econometric modelling techniques to study men and women who are major income earners in their families. I find little evidence that general stress is a pathway from SES to health. While the results suggest a strong negative association between stress and health for both men and women, they provide little support to the hypothesis of a significant effect of income on stress, consistent with the direction of the SES-health gradient. The third chapter studies whether self-assessed health status (SAH) contains information about future mortality and morbidity, beyond the information that is contained in standard "observable" characteristics of individuals (including pre-existing diagnosed medical conditions). Using a ten-year span of the Canadian National Population Health Survey, we find evidence that SAH does contain private information for future mortality and morbidity. Moreover, the extra information in SAH is greater at older ages. Our results suggest that a shift from defined benefit to defined contribution pension arrangements may carry with it the cost of exacerbated adverse selection in the market for annuities, especially at older ages. That would make it more difficult for older individuals to insure longevity risk. The fourth chapter looks at whether differences in early retirement pathways are associated with differences in post-retirement outcomes of health, stress and dwelling tenure. I use a 5 ample of men from the Canadian Survey of Labour and Income Dynamics, years 1996 to 2004. I find that differences in pre-retirement health indicators (such as self-assessed health and disability), as pathways to early retirement, are likely to be associated with differences in post-retirement health and stress. In addition, the results suggest that "involuntary" retirees (men who may have retired because of health and/or health related coniitions) are more likely to experience worse post-retirement outcomes (in terms of health and stress) than men who retire "voluntarily". Retirement circumstances are found to have no statistically significant effect on dwelling tenure. / Thesis / Doctor of Philosophy (PhD)

In 2006, the United States Congress passed the Pandemic All-Hazards Preparedness Act (PAHPA) which mandated that all emergency preparedness planning shall address at-risk populations. Further, in 2013, the reauthorization of this act, known as PAHPRA, defined at-risk individuals as "children, older adults, pregnant women, and individuals who may need additional response assistance." This vague definition leaves emergency managers, planners, and public health officials with the difficult task of understanding what it means to be at-risk. Further, once identified, the geographic location of at-risk individuals must be obtained. This research first uses the concept of social vulnerability to enhance the understanding of what it means to be "at-risk." Then, by comparing two data disaggregation techniques, areal weighted interpolation and dasymetric mapping, I demonstrate how error of estimation is affected by different scenarios of population distribution and service area overlap. The results extend an existing framework of vulnerability by stratifying factors into quantifiable and subjective types. Also, dasymetric mapping was shown to be a superior technique of data disaggregation compared to areal weighted interpolation. However, the difference in error estimates is low, 5 percent or less in 72 percent of the test cases. Only through local collaboration with community entities can emergency planners access the appropriate data to both: 1) understand the nature of at-risk individuals in their service areas and 2) spatially target resources needed to ensure all individuals are planned for in case of a bio-emergency.

No description available.

<p>This thesis presents the results of a study exploring the health status and health determinants in two farming groups in Waterloo, Ontario, Canada: Old Order Mennonites (OOMs) and non-OOM farmers. Physical health and mental health are examined, and Canada’s 12 health determinants (excluding genetics) are included in the analysis. A survey was distributed to both groups in 2010 to obtain information on health status and determinants. Comparing the two groups reduces the likely impact of contextual features impacting both, such as local economic conditions. The mental component summary (MCS) and physical component summary (PCS) of the SF-12 were used to measure mental and physical health. The study compares health in the two populations, and uses ordinary least squares (multiple) regression to determine the relative importance of the determinants in shaping health. The study found that mental health is better in OOMs, mainly due to OOM women’s strong mental health. Physical health was worse in OOMs, and while true for both genders, OOM women appear to be particularly disadvantaged. There is overlap between the groups in the determinants shaping physical and mental health. In both groups, mental health is shaped by social interaction, stress and coping; and physical health by age, childhood disease history, coping and body mass index. This suggests these factors may be important across many populations facing different life circumstances, thus representing priorities for policy action. Interestingly, the key determinants shaping physical health in both groups do not include social factors such as social capital, although social factors do shape mental health (especially in OOMs). This may be due to the rural or farming status of the two groups, or differences between physical and mental health. Determining which is more likely requires reconciling the results of this study with others, an effort hampered by differences in models, methods and health outcomes employed.</p> / Doctor of Philosophy (PhD)

Introduction. Les programmes de vélos en libre-service (PVLS) représentent une innovation en transport actif. À ce jour, la sensibilisation à cette innovation en tant que prérequis à l’accessibilité n’a jamais été étudiée. Objectif. Identifier les facteurs liés à l’absence de sensibilisation à l’existence du PVLS à Montréal. Méthode. 7011 Montréalais âgés de 18 ans et plus ont été interrogés au cours de 3 sondages téléphoniques sur une période couvrant deux saisons : avant la première saison (n=2000), après la première saison (n=2502) et après la deuxième saison (n=2509). Des analyses de régression logistique ont été réalisées sur 93,6 % (n=6562) de l’échantillon pour examiner l’effet du temps, de la proximité des stations de vélos et du niveau d’éducation sur l’absence de sensibilisation à l’existence du PVLS. Résultats. Nous constatons que, après la première saison d’implantation du PVLS, la probabilité d’absence de sensibilisation au PVLS est plus élevée chez les individus dont le niveau d’éducation est faible que chez ceux dont le niveau d’éducation est élevé (RC = 1,60; 95 % IC : 1,18; 2,19). Aussi, nous observons que, après la deuxième saison d’implantation, la probabilité d’absence de sensibilisation au PVLS est plus élevée chez les individus dont le niveau d’éducation est faible et qui vivent dans un voisinage pourvu d’un PVLS, que chez ceux dont le niveau d’éducation est élevé et qui vivent dans un voisinage dépourvu d’un PVLS (RC = 1,63, 95 % IC : 1,01; 2,64). Conclusion. Malgré l’accessibilité au PVLS dans un voisinage, des inégalités sociales persistent. / Background. Public bicycle share programs (PBSP) are an active transportation innovation. No study has examined lack of awareness of PBSP as a factor limiting accessibility. Objective. Identify factors associated with lack of awareness of a PBSP across time in Montreal. Methods. Within the context of a larger study, a sample of 7,011 Montrealiers aged 18 years and over were recruited to participate in one of three telephone surveys occurring prior to implementation (n=2,000), after season 1 (n=2,502), and after season 2 (n=2,509). Multivariable logistic regression analyses were used to investigate associations between survey period, proximity to docking stations, and education with lack of PBSP awareness. Results. There was a greater likelihood of being PBSP-unaware among those with lower education after season 1 implementation in comparison to those with higher education (OR = 1.60, 95 %CI: 1.18, 2.19). There was also greater likelihood of being PBSP-unaware among those with lower education after season 2 implementation in neighbourhoods where the PBSP was available in comparison to those with higher education in neighbourhoods without PBSP docking stations (OR = 1.63, 95 %CI: 1.01, 2.64). Although lack of awareness decreased over time, greater likelihood of being PBSP-unaware was observed among those with lower education. Conclusion. Despite the physical presence of PBSP docking stations in neighbourhoods, socioeconomic inequalities persist.

Background South Africa has experienced the most severe consequences of the HIV/AIDS pandemic. Every community has been affected in some way, many experiencing huge increases in mortality,particularly before antiretroviral therapies (ART) were readily available. However, the micro-level understanding of the HIV epidemic in South Africa is weak, because of a lack of detailed data for most of the population. This thesis is based on detailed individual follow-up in the Agincourt Health and Demographic Surveillance Site (HDSS) located in the Agincourt subdistrict of Mpumalanga Province and investigates micro-level determinants of HIV epidemiology and the impact of treatment provided. Methods The Agincourt HDSS has followed a geographically defined population since 1992,approximately the time when the HIV/AIDS epidemic first became apparent. This population based surveillance has included capturing details of all deaths, with cause of death determined by verbal autopsy, as well as the geographical location of individual households within the overall Agincourt area. Background information on the roll-out of ART over time was also recorded. Results A comparison immediately before and after the major roll-out of ART showed a substantial decrease in HIV-related mortality, greater in some local communities within the area than others. Individual determinants associated with a decreased risk of HIV/AIDS mortality included proximity to ART services, as well as being female, younger, and in higher socioeconomic and educational strata. There was a decrease in the use of traditional healthcare sources and an increase in the use of biomedical healthcare amongst those dying of HIV/AIDS between periods before and after the roll-out of ART. Conclusions Understanding micro-level determinants of HIV/AIDS infection and mortality was very important in terms of characterising the overall epidemic in this community. This approach will enable public health interventions to be more effectively targeted towards those who need them most in the continuing evolution of the HIV/AIDS epidemic.

There are significant mental health disparities in Aboriginal communities in Canada as a result of historical assimilation policies (Health Canada, 2012). One approach to mitigating these mental health concerns is through prevention programs that include a wilderness component. Wilderness based programs for Aboriginal youth are informed by cultural wisdom and empirical research that connects immersion in nature with psychological well-being. The goal of this study was to collaborate with two community partners (Nala Winds canoe family from the Heiltsuk First Nation, and Victoria Native Friendship Centre) to develop an evaluation tool that will satisfy mainstream funding standards as well as community, cultural standards. This tool-kit was designed to reflect the youth experience and mental health consequences of Tribal Journeys, an annual canoe journey program for Coastal First Nations peoples. The findings were shared with community partners and may be helpful in facilitating the creation, maintenance, and evaluation of other Aboriginal youth programs. / Graduate / 0620 / 0347 / 0621 / tansmethurst@gmail.com