Department of Public Health Sciences Graduate Theses

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    The Burden of Steatotic Liver Disease in Canada: Sex Differences in Prevalence and Cardiometabolic Profiles
    (2024-08-21) Burnside, Jessica; Public Health Sciences; Saeed, Sahar
    Background: Steatotic Liver Disease (SLD) is largely absent from public health agendas. We conducted Canada's first SLD prevalence study, focusing on sex disparities. Methods: We used 2012-2018 data from the comprehensive arm of the Canadian Longitudinal Study on Aging (n=30,097), a cohort that prospectively follows adults between 45 and 85 years old from 11 sites across Canada. Data on sociodemographic, lifestyle, and clinical factors are collected every 3 years. Steatosis was identified with the serum biomarker-based NAFLD Ridge Score (NRS) that uses ALT, HDL cholesterol, triglycerides, hemoglobin A1c, leukocyte count, and hypertension. An NRS dual cut-off <0.24 (rule-out steatosis) and >0.44 (rule-in steatosis) has a sensitivity of 92% and specificity of 90%. We estimated the prevalence of metabolic (dysfunction)-associated steatotic liver disease (MASLD), metabolic (dysfunction)-associated alcohol-associated liver disease (MetALD) and alcohol-associated liver disease (ALD). Poisson regression with robust standard errors and sampling weights were used to estimate adjusted prevalence ratios (aPR) with (95% CI). We also explored the association between total household income and incident cases of MASLD. Sensitivity analyses evaluated the extent of measurement error and missing data. Results: Our observational cohort included 24,888 people (51.4% female, median age 58 years (IQR: 51-67)). The most common subtype of SLD was MASLD, 35% (34-36%), followed by MetALD 2.6% (2.3-2.9%), and ALD 0.8% (0.6-1.0%). Prevalence of males with MASLD was 46% (45-48%) compared to 24% (23-26%) females with MASLD and males with MetALD 3.7% (3.2-4.2%) compared to females 1.6% (1.2-2.1%). After stratifying by sex and adjusting for age and lifestyle factors, differences in prevalence by income were more pronounced in females than in males. Lower household incomes were associated with higher MASLD prevalence in females (aPR: 2.9, 2.4-3.5) and males (aPR: 1.13, 1.01-1.28). We also found significant sex disparities in disease management: 38% (95%CI: 35-42%) of females had low HDL cholesterol but were not on lipid-lowering therapy, compared to 29% of males (95%CI: 26-32%). Discussion: In this large Canadian cohort, we found significant sex disparities in MASLD prevalence, cardiometabolic risk factors, and management. Epidemiological assessments are crucial in improving national preparedness for the projected increase in advanced liver disease.
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    Spatial Inequalities of Maternal Emergency Department Visits During Pregnancy and Postpartum in the Two Largest Urban Centres in Alberta: A Tale of Two Citites
    (2024-08-19) Brandwood, Alec Janes; Public Health Sciences; Ospina, Maria; Rowe, Brian
    Introduction: The perinatal period is extremely sensitive with immediate and long-term consequences for both the mother and child. In Alberta, inequalities exist in maternal utilization of emergency department (ED) services across socioeconomic groups and several demographic and clinical characteristics. However, the geographic distribution of these inequalities has not been fully explored. The aim of this study was to identify geographic inequalities in maternal ED utilization during pregnancy and postpartum in Calgary and Edmonton, two major urban centres in Western Canada. Methods: We conducted a cross-sectional geographic analysis of data from a retrospective cohort of all pregnancies leading to live births that occurred between 2011 and 2017 within the city limits of Calgary and Edmonton. Dissemination areas were used as the geographic unit to aggregate all ED visits. Spatial filters were used to generate spatial groups for the identification of geographic inequalities in the prevalence of maternal ED utilization, through a Concentration Index approach, in both Calgary and Edmonton. The percentage of individual and ED-visit characteristics were compared across the area groups delineated by the spatial filters. Results: The average gap between areas with the highest and the lowest prevalence of maternal ED utilization was 1.8-fold in Calgary and 2.3-fold in Edmonton. During the postpartum period, the difference was 2.18-fold for Calgary and 2.70-fold for Edmonton. Results from the concentration index showed moderate inequality in Calgary (-0.14 for pregnancy; - 0.14 for postpartum) and Edmonton (-0.17 for pregnancy; -0.20 for postpartum). Areas of higher ED utilization were associated with a higher percentage of women under 25 years at birth, comorbid mental health conditions, inadequate prenatal care, and a lower percentage of obstetric-related ED visits. In Edmonton, the percentage of pregnancies with major or minor comorbidities were greater in areas of higher ED utilization. Conclusion: Geographic inequalities in maternal ED utilization were not completely explained by the spatial distribution of socioeconomic status. Geographic patterns of inequality during the pregnancy and postpartum period were identified. Age, comorbidities including both mental health and major or moderate chronic conditions, inadequate prenatal care, and lower prevalence of obstetric-related visits were associated with areas of higher ED utilization.
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    Immigrants’ Use of Online Mental Health Services during the COVID-19 Pandemic
    (2024-08-16) Yaman, Rola; Public Health Sciences; Stuart, Heather; Linden, Brooke
    Purpose: Canadian immigrants tend to have poorer mental health than Canadians and lower access to mental health resources. Online mental health services (OMHS) offer promise in improving access to mental health care and has not been well-researched for Canadian immigrants. Thus, this study characterized Canadian immigrants’ OMHS use during the COVID-19 pandemic considering confounders (i.e., age and previous OMHS use) and effect modifiers (i.e., gender and income). Methods: Data collected by Mental Health Research Canada were used to evaluate the prevalence of OMHS use and immigrants’ access to OMHS. Immigrant groups were defined by generation status and newcomer status, examined with separate models. First generation immigrants were defined by being born abroad, second generation by being born in Canada with at least one parent born abroad, and third generation by being born in Canada with both parents. Multiple logistic regressions accounted for confounders and effect modifiers. Pandemic phase was explored as a hierarchical variable, but included as a covariate instead due to insufficient evidence suggesting clustering. Results: From February 2021 to July 2022, self-reported OMHS use was 11.5%, nearly double the pre-pandemic prevalence of 6.5%. First generation immigrants had significantly lower odds of OMHS use (OR=0.558, 95% CI: 0.409-0.761) compared to third generation Canadians, while second generation Canadians had similar odds (OR=0.987, 95% CI: 0.726-1.342), controlling for covariates. Younger age, self-identifying as female, low income, previous OMHS use, and later pandemic phase increased the odds of OMHS use compared to older age, being male, medium or high income, no previous OMHS use, and earlier pandemic phase. Interactions between immigrant status with income and gender were significant only for first generation immigrants. The second model indicated similar odds of OMHS use for immigrants who lived in Canada for less than five years and those who lived in Canada for more than five years when controlling for age and previous OMHS use (OR= 0.961, 95% CI: 0.722-1.279). Conclusion: This study provided an understanding of immigrants’ OMHS access in Canada and factors influencing OMHS use. It highlighted the need for strategies to increase access for first generation immigrants to ensure equitable OMHS access.
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    Real-World Effectiveness Of Bevacizumab As Firstline Treatment For Women With Advanced Cervical Cancer In Ontario
    (2024-08-13) Zhou, Shi Jie; Public Health Sciences; Ethier, Josee-Lyne; Richardson, Harriet
    Background & Objective: Advanced cervical cancer is an aggressive disease with poor prognosis and stagnant treatment innovations. A potential shift occurred in 2016 when bevacizumab became publicly funded to treat this disease in Ontario driven by the promising results from the GOG-240 study. However, access and effectiveness of bevacizumab in everyday practice has not been explored since funding approval. Approach: A retrospective cohort study, with a quasi-experimental component, was conducted using pre-linked administrative data held at the Division of Cancer Care and Epidemiology, Sinclair Cancer Research Institute. Provincial administrative data was used to identify all cervical cancer patients who received frontline palliative treatment in Ontario between January 2006 to December 2022. The funding approval event for bevacizumab – which occurred in January 2016- served as the separation event for the two study time eras defined as “pre-bevacizumab (2006-2015)” and “post-bevacizumab (2016-2022)”. Bevacizumab uptake was described in the post-funding approval era. Median overall survival (mOS) was computed using Kaplan-Meier curves; the rate of death (hazard) in each era was compared with a multivariable Cox proportional-hazards (PH) model and hazard ratio. Results: Between January 2006 to December 2022, there were 208 adult women who met study inclusion. Bevacizumab uptake, post funding approval, was 44%; younger women and women with higher income were more likely to receive bevacizumab. Median OS was 9 months and 11 months in the pre- and post-funding approval era, respectively. The adjusted hazard ratio was 0.5 (95%CI: 0.4, 0.8; p=0.0004). Conclusion: This study provides insight on the real-world effectiveness and potential uptake barriers for a costly cervical cancer therapy in Ontario. These findings can inform strategies to improve access to novel therapies for advanced cervical cancer patients, and guide practice changes for healthcare providers and funding parties.
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    An exploration of the effects of perceived stigma on the quality of healthcare experiences among patients with mental illnesses or substance use disorders
    (2024-08-12) Wong, Kai Yin; Public Health Sciences; Stuart, Heather; Dobson, Keith; Linden, Brooke
    Objectives: Few studies have quantitatively examined the association between perceived stigma (expectations of stigma) and quality of healthcare experience among patients with mental illnesses or substance use disorders. To address this gap in stigma research, this study has two empirical objectives: 1) to determine if patients with higher expectations of stigma are more likely to report a negative healthcare experience 2) to determine if the effects of expectations of stigma on quality of healthcare experiences vary depending on the types of healthcare settings. Methods: This study used a subset of the data from a 2022 national stigma survey. The purpose of the online survey was to capture stigma experiences in the Canadian healthcare system. We focused on individuals who self-identified as having a mental illness or substance use disorder. (n=1381) Perceived stigma and quality of healthcare experiences were measured using psychometrically tested scales. A binary logistic model was estimated to measure the association between the two variables. A likelihood ratio test was performed to determine if the effects of expectations of stigma on quality of healthcare experiences were different between physical and mental healthcare settings. Results: Individuals with moderate or high expectations of stigma were more likely to report a negative healthcare experience compared to those with no or low expectations. Level of education, types of diagnosis, internal wellbeing and stigmatization from family members influenced the association between expectations of stigma and quality of healthcare experience. The effects of perceived stigma on quality of healthcare experience were not significantly different between physical and mental healthcare settings. Conclusions: This study provided empirical evidence for the association between perceived stigma and quality of healthcare experience among patients with mental or substance use disorders. There is a need for developing more effective anti-stigma interventions to reduce mental-illness and substance-use related stigma and discrimination in the Canadian healthcare system.