The goals of this dissertation were to investigate aspects of the health services utilization of marginalized persons living with HIV (PLWH), including women, recent immigrants, heterosexual men and individuals living in low income neighborhoods. In the first study, an algorithm of three physician claims for HIV-infection within a three-year period was validated for case-ascertainment of PLWH in administrative databases. The sensitivity and specificity of the algorithm were 96.2% [95% confidence intervals (CI) 95.2% to 97.9%] and 99.6% (95% CI 99.1% to 99.8%), respectively. The algorithm was used to conduct a population-based study examining rates of hospitalization among all PLWH receiving care in Ontario. The introduction of combination antiretroviral therapy was associated with more pronounced reductions in rates of total (-89.9 vs. -60.5 per 1000 PLWH; p = 0.003) and HIV-related hospitalizations (- 56.9 vs. -36.3 per 1000 PLWH; p < 0.001) among men relative to women. Between 2002 and 2008, higher rates of total hospitalization were associated with female sex [adjusted relative rate (aRR) 1.15; 95% CI: 1.05 to 1.27] and low socioeconomic status (aRR 1.21; 95% CI: 1.14 to 1.29). Higher rates of HIV-related hospitalizations were associated with low socioeconomic status (aRR 1.30; 95% CI: 1.17 to 1.45). Recent immigrants had lower rates of both total (aRR 0.70; 95% CI 0.61 to 0.80) and HIV-related hospitalizations (aRR 0.77; 95% CI 0.61 to 0.96). Finally, a theoretically-informed qualitative study was conducted to characterize the help-seeking experiences of heterosexual men living with HIV. The results indicate that without the symbolic appeal of women and the social connections of gay men, heterosexual men lack the composition of capital required to benefit fully from or improve their positions within the existing HIV health and social service fields. The findings of this dissertation illustrate important disparities in health services utilization among PLWH in Ontario.

The goals of this dissertation were to investigate aspects of the health services utilization of marginalized persons living with HIV (PLWH), including women, recent immigrants, heterosexual men and individuals living in low income neighborhoods. In the first study, an algorithm of three physician claims for HIV-infection within a three-year period was validated for case-ascertainment of PLWH in administrative databases. The sensitivity and specificity of the algorithm were 96.2% [95% confidence intervals (CI) 95.2% to 97.9%] and 99.6% (95% CI 99.1% to 99.8%), respectively. The algorithm was used to conduct a population-based study examining rates of hospitalization among all PLWH receiving care in Ontario. The introduction of combination antiretroviral therapy was associated with more pronounced reductions in rates of total (-89.9 vs. -60.5 per 1000 PLWH; p = 0.003) and HIV-related hospitalizations (- 56.9 vs. -36.3 per 1000 PLWH; p < 0.001) among men relative to women. Between 2002 and 2008, higher rates of total hospitalization were associated with female sex [adjusted relative rate (aRR) 1.15; 95% CI: 1.05 to 1.27] and low socioeconomic status (aRR 1.21; 95% CI: 1.14 to 1.29). Higher rates of HIV-related hospitalizations were associated with low socioeconomic status (aRR 1.30; 95% CI: 1.17 to 1.45). Recent immigrants had lower rates of both total (aRR 0.70; 95% CI 0.61 to 0.80) and HIV-related hospitalizations (aRR 0.77; 95% CI 0.61 to 0.96). Finally, a theoretically-informed qualitative study was conducted to characterize the help-seeking experiences of heterosexual men living with HIV. The results indicate that without the symbolic appeal of women and the social connections of gay men, heterosexual men lack the composition of capital required to benefit fully from or improve their positions within the existing HIV health and social service fields. The findings of this dissertation illustrate important disparities in health services utilization among PLWH in Ontario.

This study examines the prevalence of methicillin-resistant Staphylococcus aureus in midwestern swine herds and the workers in those herds.

Clostridium difficile infection (CDI) is the most common cause of hospital-acquired infectious diarrhea in the United States. Although C. difficile is widely-recognized as a pathogen among hospitalized populations, CDI has emerged in the community setting but is under-diagnosed. This study sought to increase knowledge about the incidence of, risk factors for, and outcomes associated with community-associated CDI (CA-CDI). A retrospective nested case-control study was conducted using insurance claims data from the Wellmark Data Repository for the time period between January 1, 2003 and December 31, 2007. Persons with CDI were identified and were classified as community-associated CDI and hospital-acquired CDI. During this time, 304 cases of CA-CDI and 338 cases of HA-CDI were identified. Within this population, the incidence rate for CA-CDI was 11.16 cases per 100,000 person-years, whereas the incidence rate for HA-CDI was 12.41 cases per 100,000 person-years. Conditional logistic regression was utilized to determine the risk for CA-CDI related to pharmacologic exposures, comorbidity, demographic characteristics, and healthcare utilization. Prior to controlling for other risk factors and covariates; being over the age of 50 years, gender, history of hospitalization, number of outpatient physician visits, antimicrobial use, gastric acid suppressant use, underlying comorbidity, and diagnosis of gastrointestinal disease (including IBD, diverticular disease, GERD) were associated with the development of CA-CDI. However, after adjustment for all covariates, increased risk for CA-CDI within this population was consistently associated with antimicrobial use, being between the age of 19 and 74 years, and diagnosis of inflammatory bowel disease. Gastric acid suppressant use was a risk factor in a number of models, although this association was not consistent. Furthermore, persons who last received antimicrobials in the previous 150 days and persons who received a greater number of different antimicrobial agents were at increased risk for CA-CDI. Antimicrobial use was the primary risk factor for CA-CDI, although 27% of cases did not have prior exposure to antimicrobials. In fact, 17% of CA-CDI cases did not have any of the traditional risk factors for CDI (i.e., no antimicrobial or gastric acid suppressant exposure, no underlying illness, and no history of hospitalization). Furthermore, none of the CA-CDI cases underwent surgical procedures attributable to CA-CDI, although approximately 25% of CA-CDI cases were hospitalized with a diagnosis of CDI. This research demonstrates that CDI is occurring in the community setting and in populations that were previously not considered to be at risk. In this study, the risk factors for CA-CDI were similar to those identified in hospitalized populations, although it was not uncommon for persons to develop CA-CDI without any of these risk factors. Furthermore, the characteristics of persons with CA-CDI and the outcomes in this group were different than those previously reported among hospital-acquired CDI cases. Collectively, this study provides valuable knowledge about the epidemiology of CA-CDI and serves as a foundation for future research.

Diarrheal disease is one of the leading causes of mortality of children under 5 years of age. Despite this, diarrheal disease is easily preventable through adequate water, sanitation and hygiene. Sanitation access is currently classified as “improved” or “unimproved” based on level of latrine access. This does not account for differences in human behaviors, or differences in exposure risk. A sanitation score was built using behavioral and access data in order to better classify the sanitation environment of a household. Due to low levels of sanitation access and practice of open defecation in Ghana, households in four neighborhoods in Accra, Ghana were selected to participate in the data collection. Data was collected through a survey, environmental sanitary inspections and collection of hand rinse and environmental swab samples. These samples were then tested for fecal indicators, by measuring presence and concentration of E. coli and human Adenovirus. A novel sanitation score based on latrine access and use for each household was created. Hierarchical linear and logistic regression was used to compare the sanitation score to the environmental contamination as indicated by the E. coli and Adenovirus. Higher sanitation scores were significantly associated with increases in Adenovirus concentration (PR=1.6, 95%CI=1.1, 2.2). The sanitation score was not significantly associated with E. coli or presence of Adenovirus. Further development of a sanitation score variable could help to better understand sanitation environments.

<p>Cigarette smoking is prevalent in HIV-infected people, resulting in higher mortality rate and more premature heart and lung diseases in the highly active antiretroviral therapy era. Smoking is a modifiable risk factor for these adverse outcomes and smoking cessation in HIV-positive smokers is feasible, although further efforts are needed to improve smoking cessation programs in HIV-positive persons.</p> <p>In this thesis, I examined the role of smoking in mortality and morbidity in HIV-positive Ontarians, and piloted a smoking cessation program featuring a novel smoking cessation aid, varenicline, in HIV-infected smokers. In addition, I explored three different methods to resolve missing data, by excluding, grouping and multiply imputing missing data. I adopted three different study designs in my thesis studies: retrospective cohort, cross-sectional and open label study.</p> <p>We found smoking prevalence in HIV-infected people was consistently higher than in the general population. Smoking was associated with a higher risk of death, of respiratory symptoms, hospitalization and chronic obstructive pulmonary disease, and with reduced lung function and less CD4-T-lymphocyte improvement over time. We found varenicline was as effective in HIV-positive smokers as in non-HIV smokers reported by previous studies.</p> / Doctor of Philosophy (PhD)

<p>Human rhinovirus (HRV) is a single-stranded RNA virus responsible for causing the common cold and exacerbating chronic respiratory diseases. HRV is the most common cause of acute respiratory illness. Unfortunately, difficult culturing conditions and perceived mild symptoms have limited our understanding of HRV. This thesis characterizes fundamental aspects of HRV such as viral load in different patient populations, prevalence and diversity of HRV, and severity and duration of infection.</p> <p>We developed an HRV qPCR assay to quantitate HRV in clinical isolates. We used this assay to measure viral loads in hospitalized and community members. We found that HRV viral loads were similar regardless of age and need for hospitalization. Viral loads were significantly lower amongst individuals with asymptomatic HRV infection than symptomatic HRV infection. Next, we determined the prevalence and diversity of HRV in children and adults. We found that HRV is the most common respiratory pathogen in September-October in both children and adults. A broad range of HRV genotypes can be found circulating amongst children and adults; however HRV C is more prevalent in children. Furthermore, we investigated the association of HRV C duration and severity of illness. Among otherwise healthy individuals, HRV C did not persist longer than HRV A/B, nor was the viral load significantly different. In hospitalized children, HRV C was not more associated with an asthma or wheeze diagnosis. Overall, our data suggest that viral loads do not predict the severity of illness, HRV C commonly occurs in children, and behaves like other HRV species.</p> / Master of Science (MSc)

<p>Physical activity is known to benefit many physiological processes, including bone turnover. There are; however, currently no clinical guidelines regarding the most appropriate type, intensity and duration of activity to prevent bone loss. To address this gap in the literature, we performed a retrospective analysis of data from the Canadian Multicentre Osteoporosis Study (CaMos), a prospective cohort of 10,000 adult patients. Female participants aged 75 and over provided information regarding their daily activity levels, including the amount of time spent each week performing moderate physical activity (e.g. housework, brisk walking). Outcome measures included bone mineral density and fracture rate. Multiple and linear regression analysis was used to determine the effect of increasing amounts of moderate physical activity on the outcome measures. The results indicate that a step increase in the amount of physical activity performed each day resulted in a positive effect on bone mineral density at the hip, Ward's triangle, trochanter and femoral neck (B=0.006 to 0.008, p</p> / Master of Science (MSc)

<p><strong>Objective: </strong>To provide an overview of the state of trial methodology concerning measurement of patient adherence and patient recruitment, and explore how the quality of these methods impact the adherence results found in trials.</p> <p><strong>Data sources: </strong>Major bibliographic sources, reference lists, and clinicaltrials.gov were searched for relevant trials up to January 2013.</p> <p><strong>Study selection: </strong>Approximately 150 trials were included in the full systematic review, from which 50 trials were selected to represent several methods of measuring adherence.</p> <p><strong>Results: </strong>There were a variety of different measures of adherence with qualities ranging from valid and unobtrusive, to unreliable and subjective. The median overall quality of adherence measures was 5 (IQR 3, maximum score 9, higher is better). The overall correlation of the quality of the measures of adherence and the coefficient of variation (CV) or proportion adherence suggested that adherence measures rated as higher quality were associated with a higher CV but not associated with a lower proportion adherence. The median overall quality of patient recruitment methods was 2 (IQR 1, maximum score 6, higher is better). The correlation of the power of a trial and the quality of the patient recruitment methods, was slightly positively correlated for both binary and continuous data.</p> <p><strong>Conclusions: </strong>The quality of methods employed in adherence trials varies considerably and affects at least some findings of these trials. The importance of these differences in quality merits further study, but it is clear that better standards of adherence measurement are needed to support adherence research.</p> / Master of Science (MSc)

<p>Upper respiratory tract infection (URTI), which presents clinically as the common cold, is the most common form of respiratory illness experienced by humans and is a major cause of morbidity and hospitalizations. Currently, URTI prevention focuses on hand hygiene with some consideration given to other lifestyle factors such as sleep, nutrition, and exercise. Identifying additional interventions for the prevention of URTI could reduce the burden of this disease.</p> <p>In this thesis, I examine the role of vitamin D3 supplementation and tap water gargling for the prevention of URTI. I employ experimental and observational study designs to assess the effect of these interventions on the risk of URTI in the context of a randomized controlled trial of 600 participants, and a longitudinal cohort of 416 participants. Further, I investigate the association between modifiable lifestyle factors and risk of URTI using data from the longitudinal cohort. Data from this study is also used to explore statistical methods for the analysis of repeated events.</p> <p>When evaluating self-reported, clinical URTI, all analyses supported the use of vitamin D3 supplementation to reduce the risk of URTI. However, this finding was only statistically significant in the analysis of the longitudinal cohort study; results from the RCT indicated that vitamin D3 supplementation statistically significantly reduced the risk of laboratory confirmed infections but had a non-significant benefit for clinical infections. Gargling did not reduce the risk of clinical or laboratory confirmed infections.</p> / Doctor of Philosophy (PhD)