Health Sciences - Theses, Dissertations, and other Required Graduate Degree Essays

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Understanding a public bicycle share program in Vancouver, Canada: program uptake and impacts on bicycling

Author: 
Date created: 
2018-09-25
Abstract: 

Public bicycle share programs have the potential for positive health and environmental benefits. In order for these benefits to be realized, the programs need to be well used at the population level and contribute to increases in bicycling. This thesis aimed to understand demand for the Vancouver public bicycle share program among residents and the impact of the program on bicycling. We used data from a public bicycle share member survey and a repeat cross-sectional survey of Vancouver residents. As of Fall 2017, approximately 6.2% of Vancouver residents have used the public bicycle share program, and amongst non-users, nearly 1 in 4 indicate they are likely to use the program. However, we did not observe an increase in bicycling for those living and/or working inside the bicycle share service area relative to those outside the service area in the second season of program operation.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Meghan Winters
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

A randomized controlled trial of prenatal air pollution exposure and the development of allergic sensitization in infancy

Author: 
Date created: 
2018-07-12
Abstract: 

Background: Prenatal exposure to PM2.5 has been associated with the development of allergic sensitization in children. We conducted a single-blind, randomized controlled trial in Ulaanbaatar, Mongolia to test the effectiveness of HEPA filter air cleaner use during pregnancy on the risk of allergic symptoms in the first year of life. Methods: We enrolled 540 pregnant women at 10.3 weeks’ gestation, on average, and randomly assigned them to the intervention group (N = 217), which received one or two air cleaners (depending on home size) to use from enrollment until childbirth, or the control group (N = 187). We measured indoor PM2.5 concentrations over 7-days at ~11 weeks’ gestation and again at ~31 weeks’ gestation. We surveyed mothers about eczema, wheeze, respiratory infections and otitis media in the first year of life. The effectiveness of the intervention was analyzed using logistic regression in intention-to-treat analyses. Results: Baseline characteristics were similar between the two groups. PM2.5 concentrations were 29% lower, on average, in intervention homes than control homes (95% CI: 21-37%). The prevalence of outcomes ranged from 8.2% for wheeze to 54% for eczema. The intervention was significantly associated with a reduction in wheeze (OR: 0.47, 95% CI: 0.22 – 0.97). For eczema (OR: 1.12, 95% CI: 0.76 – 1.66), otitis media (OR: 1.07, 95% CI: 0.64 – 1.76) and chest infections (OR: 0.91, 95% CI: 0.58 – 1.43), the 95% confidence intervals indicated both potential harmful and beneficial effects of the intervention. Conclusion: The use of HEPA filter air cleaners during pregnancy reduced the odds of parent-reported wheeze in the first year of life.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Ryan Allen
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

Assessing the relation between plasma PCB concentrations and elevated autistic behaviours using Bayesian predictive odds ratios

Author: 
Date created: 
2018-07-11
Abstract: 

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by impaired social communication and repetitive or stereotypic behaviours. In utero exposure to environmental chemicals, such as polychlorinated biphenyls (PCBs), may play a role in the etiology of ASD. We examined the relation between plasma PCB concentrations measured during pregnancy and autistic behaviours in children aged 3-4 years old in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. We calculated Bayesian predictive odds ratios for more autistic behaviours based on a latent variable model with a threshold of SRS >60. We found small and imprecise increases in the mean SRS score for the highest quartile of plasma PCB concentrations compared with the lowest quartile; these were accompanied by larger increases in the odds of more autistic behaviour. In conclusion, we found some evidence that plasma PCB concentrations during pregnancy may be associated with small increases in autistic behaviours in this cohort.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Lawrence McCandless
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

Potential barriers and facilitators to small businesses adopting a psychological health and safety management system

Author: 
Date created: 
2018-07-24
Abstract: 

In recent years, the importance of identifying and managing psychological risk factors in the workplace has received increasing recognition due to significant evidence that suggests that workplace factors can adversely impact the onset and duration of mental health problems among workers. This has led to the development of the National Standard of Canada for Psychological Health and Safety in the Workplace (The National Standard). Some organizations, especially large ones, have implemented, or are starting to implement, the National Standard. Notwithstanding that, there is still a lack of understanding of the facilitators and barriers to the effective implementation of a psychological health and safety management system (PHSMS). Thus, the challenges and opportunities of how small organizations put the National Standard into practice needs further study. This paper aims to examine the relevant literature and perform a search to identify potential facilitators and barriers that may affect small businesses in the process of implementing a PHSMS. In addition, some recommendations have been provided to assist small business in overcoming these barriers.

Document type: 
Graduating extended essay / Research project
File(s): 
Senior supervisor: 
Merv Gilbert
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Project) M.P.H.

Changes in Causes of Death, the Impact on Life Expectancy, and the Risk of Myocardial Infarction Among People Living with and without HIV

Author: 
Date created: 
2023-01-11
Abstract: 

Background: Within the context of aging with HIV in the combination antiretroviral therapy (ART) era, the set of four papers that make up this dissertation aimed to: summarize the existing evidence on the risk of myocardial infarction (MI) among people living HIV (PLHIV) (Chapter 2); characterize changes over time in rates and causes of death among HIV-positive and HIV-negative individuals (Chapter 3); assess the impact of the changing causes of death on life expectancy and potential gains in life expectancy over time (Chapter 4); estimate the incidence of MI and its association with HIV infection, ART, and other explanatory variables, among HIV-positive and HIV-negative individuals (Chapter 5).Methods: A systematic review and meta-analysis of MI risk among PLHIV was initially performed. Next, data from the COAST studya linked population-based, retrospective cohort study containing longitudinal data on over half a million HIV-positive and HIV-negative adults in British Columbia (BC)were assessed to investigate several issues pertinent to aging with HIV. With the hope of producing evidence to inform relevant programmatic and clinical guidelines/policies among aging HIV-positive individuals, a series of analyses were performed to examine mortality changes over time, cause-deleted life expectancy, and the risk of MI among HIV-positive compared to HIV-negative individuals. Results: We observed significant declines in mortality and dramatic shifts in the causes of death between 1996 and 2012 among HIV-positive compared to HIV-negative individuals. Although HIV/AIDS continues to account for the greatest burden of mortality among PLHIV, other non-AIDS-defining conditions have become increasingly relevant. Consequently, our results suggest that managing cardiovascular diseases and non-AIDS-defining cancers among PLHIV has the same effect on life expectancy in this population as in HIV-negative individuals. Increasing age, male sex, and HIV infection (including exposure to some ART regimens) were found to be associated with a higher risk of MI.Conclusion: Taken together, our findings highlight the increasing need to concurrently consider multiple factors, including HIV infection itself, other emerging non-HIV-related conditions, exposure to ART, and demographic and clinical risk factors, as part of the effort to address and improve the care of aging HIV-positive individuals.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Robert Hogg
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) Ph.D.

Community engagement through the lens of intersectionality

Author: 
Date created: 
2018-04-20
Abstract: 

Despite the growing interest in community engagement as an alternative way of building evidence in public health and its potential to address health disparities in marginalized populations, there is a dearth of knowledge and evidence of the ways in which participatory approaches, such as community-based participatory research (CBPR), engage and impact people with lived experience of mental illness. Although CBPR offers the promise of addressing factors associated with mental health inequity, it faces its own set of ethical and methodological concerns related to the authenticity of community participation and a lack of understanding of the ways in which active engagement in CBPR affects community members. For people with psychiatric diagnoses, mental health inequities are a reflection of persistent and intertwined social and structural inequities rooted in historical exploitation and ongoing systemic subjugation through psychiatrization, criminalization and stigmatization of mental distress. While people with lived experience of mental illness face similar mental health inequities, the way they experience or respond to oppression is contingent on the ways it intersects with different social locations, such as gender, social status or race and power relations, such as sanism. Thus, an exploration of engagement from the participants’ perspective and a critical examination of multiple and intersecting social factors and underlying power relations are needed. In this Master’s thesis, I apply a critical lens of intersectionality to a CBPR case study (Imagining Inclusion) to examine the research question: “How do the intersections of social locations and systemic and structural processes shape the experience of engagement in CBPR for people living with mental illness?” Intersectionality-informed analysis of thirteen in-depth individual interviews with people living with a mental illness revealed three major themes: 1) definitions and dimensions of community engagement; 2) tensions around joining Imagining Inclusion and sustaining engagement; and 3) tensions around collaborative relationships. In this project, I contribute to the call for this type of consideration of engagement by employing an intersectionality lens to explore the term engagement and the experiences of engagement in Imagining Inclusion from the perspectives of people with lived experience of mental illness.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Dr. Marina Morrow
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

Elucidating the physiological adaptation of loss of retinoblastoma protein in conjunction with hypoxia in neuroblastoma cells.

Author: 
Date created: 
2017-06-22
Abstract: 

Neuroblastoma is a malignancy of multipotent embryonic neural crest cells and is the most common cancer in infancy. Since neuroblastoma tumours originate from immature sympathetic cells called neuroblasts, the effect of hypoxia on these cells is of great significance. Low oxygen pressure (hypoxia) is a physiological condition that facilitates increased malignancy and tumour progression in several solid cancers. Hypoxia Inducible factors (HIF)-1 and HIF-2 and their dimerization partner TRIP230 are the principle transcriptional regulators of the hypoxic response. Our group has previously shown that the tumour suppressor retinoblastoma protein (Rb) acts as a transcriptional repressor of hypoxia by its ability to associate with HIF-1. The role of loss of Rb in facilitating the hypoxia related-genetic programs has yet to be studied in neuroblastoma. We used CRISPR-Cas9 technologies to genetically knock-out Rb expression in two non MYCN amplified neuroblastoma cell lines, SH-SY5Y and SK-N-AS. We used a microarray platform to compare the steady-state expression levels of mRNA from these two cell lines to determine aberrant expression of hypoxia related genetic programs that increase cell motility and invasion and promote metastasis. Using migration assays, qRT-PCR and Western blot analysis we have identified multiple genes whose expression is significantly upregulated with the loss of Rb in conjunction with hypoxia. The identification and characterization of these genes could provide the basis for developing novel therapies and new diagnostic markers for treatment for children with non-MYCN amplified neuroblastoma.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Timothy Beischlag
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.

Examining the social, sexual, and technological behaviour of gay, bisexual, and other men who have sex with men

Date created: 
2018-04-04
Abstract: 

Online sex seeking (OSS) has previously been associated with condomless anal sex (CAS) among gay, bisexual, and other men who have sex with men (GBM). Previous studies suggest that this association may be due in part to the uptake of OSS among GBM who are more likely to engage in CAS. This thesis examines the interpersonal factors that might underlie this association. Data for this thesis was collected through the Momentum Health Study, a longitudinal cohort of GBM living in Metro Vancouver and recruited using Respondent-Driven Sampling. Latent class analysis, hierarchical regression, and structural equation models examined (i) patterns of online and offline community connectedness, (ii) covariates of event-level CAS within the context of online-initiated partnerships, and (iii) confounding effects of collectivism on the OSS-CAS relationship. Latent modeling of patterns of community connectedness identified three classes: Class 1, “Socialites,” (38.8%) were highly connected both online and offline. Class 2, “Traditionalists,” (25.7%) were moderately connected with little app/website-use. Class 3, “Techies,” (35.4%) had high online connectedness and relatively low in-person connectedness. In multivariable modelling, Socialites had higher collectivism than Traditionalists, who had higher collectivism than Techies. Patterns of community connectedness were also related to HIV-testing, perceptions of HIV stigma, serodisclosure, and condom use. Supporting these findings, hierarchical event-level logistic regression showed that collectivism, altruism, and social embeddedness were protective factors against CAS – particularly for HIV-negative men. Structural equation modelling revealed that collectivism, altruism, and sensation seeking accounted for approximately 40% of the association between OSS and CAS. In conclusion, these analyses suggest that collectivism, and related sociocultural constructs, promotes greater adherence to established HIV-prevention practices (such as condom use) while individualism may be more amenable to novel risk-reduction strategies which may or may not include condoms. While further research is needed to understand the plasticity of these interpersonal factors, these results suggest that programs facilitating collectivism might have the potential to establish broad sexual health norms. Furthermore, sex-positive risk reduction is likely an important component of HIV prevention for GBM who are less attuned to traditional social influences – many of whom predominantly use the Internet to connect with other GBM.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Robert S. Hogg
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) Ph.D.

The Case of "Molar City", Mexico: An Ethical Examination of Medical Tourism Industry Practices

Author: 
Date created: 
2017-12-06
Abstract: 

“Molar city” or Los Algodones, Mexico is characteristic of other medical border towns whose proximity to the Mexico-United States border enables American and Canadian patients to access desired health care. Patients can take advantage of economic asymmetries on either side of the border to purchase desired health care in an easily accessible location. Los Algodones is an exceptional industry site in northern Mexico, however, due to its focus on the provision of dental care and claims by local residents that it has the highest concentration of dentists per capita in the world. In this dissertation, I use a case study of Los Algodones’ dental tourism industry to provide an examination of ethical concerns for medical tourism industry practices. Drawing on findings from qualitative research exploring the perspectives and experiences of diverse industry stakeholders, this study contributes insight into ethical examinations for medical tourism informed by structural exploitation and structural injustice frameworks. By employing these ethical frameworks to examine one particular industry site, this research outlines how structural factors such as competition in the global industry and economic asymmetries between the global north and global south inform unfair localized industry practices. I highlight in this dissertation how industry practices are taken up by various industry stakeholders to maintain the flow of dental tourists to Los Algodones; however, efforts to promote and protect the success of the industry according to the interests of elite industry stakeholders inform practices characterized by the irresponsible use of health resources and degrading interactions. Overall, this research suggests that medical tourism industry development raises health equity concerns for the industry if exploitative practices in different industry sites produce poor labour conditions and access to care barriers for marginalized populations. Further research is needed to explore the utility of these ethical frameworks when examining other industry sites and possible policy implications for mitigating exploitative practices within different contexts of industry development.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Jeremy Snyder
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) Ph.D.

The distribution and determinants of hospital readmission among people living with HIV/AIDS in British Columbia, Canada

Author: 
Date created: 
2018-01-11
Abstract: 

Unplanned hospital readmissions are costly and common among people living with HIV/AIDS (PLWHA). However, factors associated with readmission remain poorly understood. The purpose of this study was to examine the distribution and risk factors of 30-day readmission among the population of PLWHA in British Columbia, Canada. A retrospective cohort study using linked administrative data was executed with multivariable logistic regression models to identify risk factors of readmission. Approximately 14 percent of all hospitalizations resulted in 30-day re-hospitalization, 5.5% higher than the readmission rate for the general population in Canada. Four enabling factors (longer length of stay in the index hospital admission, admission via emergency departments, leaving against medical advice, transferring between hospitals); one need factor (latest CD4 count prior to admission) and one predisposing factor (diagnostic category) were associated with an elevated odds of readmission. Policymakers should develop strategies focusing on modifiable risk factors to decrease hospital readmission among PLWHA.

Document type: 
Thesis
File(s): 
Senior supervisor: 
Bohdan Nosyk
Department: 
Health Sciences: Faculty of Health Sciences
Thesis type: 
(Thesis) M.Sc.