Doctor of Philosophy in Population and Public Health (PhD)
Preventing ovarian cancer: Human vs. machine intelligence
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Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.
Growing evidence suggests that achieving Sustainable Development Goal 3 will require high-quality health systems in low- and middle-income countries. I assessed whether routine health information systems in Rwanda capture relevant quality measures. Using data on available quality measures and time series methods, I tracked Rwandan health system performance focusing on quality of care across primary, secondary, and tertiary levels of care. Further, I performed a systematic review of the literature to investigate whether use of interrupted time series (ITS)—one of the strongest quasi-experimental designs—in the evaluation of health system quality improvement (QI) interventions has followed best practice standards and recommendations. Finally, using ITS with a concurrent control group, I evaluated the impact of three QI interventions on maternal, newborn, and child health in Rwanda. While health outcome measures were captured across all levels of care, there were gaps in the measurement of relevant quality impact measures such as confidence in health systems and economic benefit, and processes such as user experience. Information about competent care and systems was rarely available outside maternal and newborn health. Clearly, the current health information system would benefit from capturing additional healthcare quality metrics to allow the effective tracking of performance of the Rwandan health system and to identify new potential efficiencies. Available quality measures suggest that quality of care provided in Rwandan healthcare facilities has generally improved over the past decade; however, further improvements are still necessary to maximize the impact of the health system. Use of ITS in the evaluation of QI interventions has increased considerably over the past decade; however, variations in methodological considerations and reporting of ITS studies remain a concern. This warrants the development and / or reinforcement of formal reporting guidelines to improve its application in the evaluation of QI interventions. Lastly, the QI intervention that employed clinical mentorship was associated with improvements in maternal and newborn health outcomes such as a reduction in obstetrical complication case fatality, in-hospital neonatal mortality, incidence of postpartum hemorrhage and neonatal asphyxia. In contrast, those that used training approaches had a limited impact.
The discovery of antibiotics was one of the most significant advances in modern medicine; however, our reliance on antibiotics is threatened by the spread of resistance. Antibiotic resistance is a natural phenomenon that is exacerbated by selection pressure from antibiotic use. Where prescriptions are required for antibiotics, understanding prescribing behaviour is paramount. Guidelines recommend antibiotics for respiratory tract infections (RTIs) only when pneumonia or other serious complications are suspected. Urine cultures are recommended for complicated, but not uncomplicated, urinary tract infections (UTIs). The objectives of this thesis were to identify factors related to patients, physicians, and geographic regions associated with antibiotic use for RTIs, and urine culturing for UTI; and to explore the extent of variations in these practices across physicians.A systematic review of the literature was conducted to assess factors that have previously been empirically associated with antibiotic prescribing. Then, using linked administrative datasets, factors associated with antibiotic prescriptions for paediatric respiratory tract infection were analyzed. Urine culture data was subsequently linked in, to explore urine culturing practices. These analyses demonstrated that observed physician characteristics had a stronger influence on practice patterns that did differences in patient characteristics. In particular, physicians who had been in practice for longer tended to be more likely to prescribe antibiotics, and to order urine cultures. Physicians trained outside of Canada were more likely to prescribe, but less likely to order a urine culture. Female physicians were less likely to prescribe antibiotics, and more likely to order urine cultures. The variation between physicians that remained after accounting for observed characteristics was substantial. This research demonstrates some common features of physicians that are associated with antibiotic prescribing and urine culture use. However, the variation between physicians in practice styles is greater than the effects of these characteristics. These findings have implications for the design and implementation of antibiotic stewardship efforts to improve antibiotic use. For example, audit and feedback interventions and academic detailing have shown some promise, and may be particularly effective if targeted to physicians with higher prescribing or culturing practices. This thesis demonstrates the utility of administrative datasets in identifying such physicians.
Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.
The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.
Introduction: The Choosing Wisely Canada (CWC) campaign aims to facilitate discussion between patients and providers about what procedures, tests, and treatments are unnecessary. The results of previous evaluations of the CWC recommendations on the use of unnecessary care from various specialties, however, are not consistent. This thesis aims to build upon the previous body of research by evaluating the impact of the CWC recommendations regarding the appropriate prescription of psychiatric medications for young people. Specifically, I assessed the impact of three specific recommendations on the drug utilization, time to treatment, and costs.Methods: To evaluate the impact of the CWC recommendations on the use psychiatric medications among young people in British Columbia, I identified all patients with incident diagnoses and prescription fills for the recommendations under study: selective serotonin reuptake inhibitors (SSRIs) among adolescents (
Background - Prescription medications, which are a critical component of modern medicine, are not covered under the Canada Health Act. Canadian prescriptions are financed through a combination of public financing, private insurance, and out-of-pocket payments. This leaves potential coverage gaps amongst different segments of the population. There are current discussions of a national pharmacare strategy to address this issue. It remains unclear how such a policy, particularly for seniors, should be financed.Methods – We first studied British Columbia’s publicly-funded pharmacare program to examine the impact of income-based deductibles on older adults with chronic obstructive pulmonary disease (COPD) in regards to prescription drug utilization and other health services. This was analyzed utilizing a regression discontinuity design with administrative datasets. The second study used logistic regression to examine the trend in employer-sponsored health insurance (EHI) availability amongst Ontario’s retirees from 2005 to 2014 using data from the Canadian Community Health Survey.Results - Deductibles had no effect on prescription utilization amongst a cohort of older adults living with COPD in BC. However, over 40% of the eligible person-years analyzed did not obtain a prescription for COPD treatment, suggesting severe under-treatment in this population. Results also suggest an increased use of inhaled corticosteroids, which may be due to a special authority process and may not be appropriate for COPD. A decline in EHI availability was apparent for Ontario’s retirees between 2005 and 2013-2014. EHI availability is strongly linked to household income, with those of a lower income-decile having the lowest odds of having EHI. Conclusion - Imposing a modest income-based deductible was not found to impact prescription utilization or utilization of other health services, even amongst a population with a chronic condition facing comparatively high prescription costs. In contrast, supplemental help in making prescriptions more affordable for the older adult population may be diminishing. A small but statistically significant decrease was observed in EHI – the main source of aid in prescription affordability apart from the public system. These results suggest that a comprehensive strategy to address medication adherence is warranted to minimize future health system burden.
Background: Sofosbuvir and ledipasvir-sofosbuvir are breakthrough direct-acting antiviral agents (DAAs) for the treatment of hepatitis C virus (HCV) infection. These drugs were very expensive at initial listing with a price of around $60,000 CAD. However, the cure rates and side effect profiles showed drastic improvements compared to interferon-based treatments. Given limited real-world data on adherence to DAAs, this study examined adherence to sofosbuvir and ledipasvir-sofosbuvir, and identified factors associated with adherence. It also examined the impact of public prescription drug coverage (PharmaCare) on adherence, treatment uptake, and expenditure. Methods: This study used data from the British Columbia Hepatitis Testers Cohort. Adherence was measured as proportion of days covered (PDC), calculated from prescription drug data. I used multivariable logistic regression to examine the impact of various factors on full adherence (PDC=100%). I also used interrupted time series analysis to examine the impact of PharmaCare coverage on adherence, treatment uptake, and public and private expenditure over time. Results:Of 3,730 treatments initiated, 2,760 were eligible for analysis; 786 were treated with sofosbuvir, 1,974 were treated with ledipasvir-sofosbuvir, and 14 were treated with both. Mean PDC across both drugs, sofosbuvir, and ledipasvir-sofosbuvir were 96.17%, 95.35%, and 96.50% respectively. In the multivariable logistic regression model, several factors were statistically significant. Major mental illness, longer treatment durations, moderate socioeconomic status, and being of white ethnicity were all associated with lower proportions of individuals with full adherence. Having PharmaCare coverage and being over the age of 60 were associated with higher proportions of individuals with full adherence. In the interrupted time series analysis, the availability of PharmaCare coverage for sofosbuvir and ledipasvir-sofosbuvir did not impact trends in adherence, but did increase treatment uptake of both drugs. Furthermore, public expenditure increased after the policy change, crowding out some of the private expenditure. Conclusion: Given the high cost of these drugs, the high adherence rates found are encouraging. Strategies to target those with major mental illness and longer treatment durations should be explored. Payers should also be prepared for increased treatment uptake and public expenditures following the availability of public coverage.
Background – Erectile dysfunction (ED) has been described as providing a ‘window of curability’ for men at risk of future cardiovascular disease, however there is little evidence on the relationship between erectile dysfunction and modifiable cardiometabolic risk factors. The primary objectives of this thesis were to: 1) determine whether men with ED have a higher risk of having an undiagnosed cardiometabolic risk factor (hypertension, hypercholesterolemia and diabetes), and 2) determine whether the prescription of a phosphodiesterase type 5 inhibitor (PDE5i) for ED leads to an increase in the diagnosis and treatment of these risk factors. Methods – This thesis comprised of two original studies. The first, a cross-sectional analysis using a nationally representative survey from the United States. The second, a population-based empirical study of changes in drug utilization for cardiometabolic risk factors following PDE5i prescription in British Columbia. An individual-level time series analysis with switching replications was utilized for this analysis. Results – Men with ED were found to have double the odds of having undiagnosed diabetes compared to those without ED. This was most significant among middle-aged men (ages 40-59 years), as the predicted probability of having undiagnosed diabetes increased from 1 in 50 in men without ED to 1 in 10 in men with ED. Among men aged 40 to 59 years old in British Columbia, we found a sudden increase in prescriptions for antihypertensives (28 per 1,000), statins (15 per 1,000), and antidiabetics (18 per 1,000) in the 90 days following a new prescription for a PDE5i. For both hypercholesterolemia and diabetes, relevant screening tests performed in the 30 days following PDE5i prescription were responsible for this change. This increase was followed by a significant declining trend in prescriptions for all three drugs. Conclusions – Men with ED have an increased risk for undiagnosed cardiometabolic risk factors. PDE5is can act as a ‘gateway drug’ for men to be newly treated for these risk factors provided physicians perform the requisite screening investigations. Increased education and awareness of this relationship among both patients and physicians is critical for exploiting the potential for preventing future cardiovascular disease.