Repository logo



Journal Title

Journal ISSN

Volume Title





Degree Level



Profound advances in cardiovascular disease (CVD) treatments have been made over the last two decades. However, poor adherence to preventative therapies remains a critical problem in the health of Canadians. Despite decades of research, contemporary knowledge about adherence is often based on theory that has not been confirmed with quantitative research findings. For example, adherence to preventative medications is widely considered to reduce risks for major health outcomes. However, major differences in the estimation of medication adherence benefits exist. Thus, a study was conducted to determine if the association between poor adherence and the risk of death was influenced by the method used to identify optimal adherence. The impact of adherence to statin medications on mortality was assessed among a cohort of 9,051 individuals who received a statin medication following discharge from a hospitalization for acute coronary syndrome (ACS). Using a fixed-summary measure, optimal adherence to statins was not associated with mortality benefits (adjusted HR 0.97, 95%CI 0.86 to 1.09, p=0.60). In contrast, the repeated measures approach resulted in a significant 25% reduction in the risk of death among adherent individuals (adjusted HR 0.75, 95%CI 0.67 to 0.85, p<0.01). However, neither estimate could be regarded as the most robust. Thus, until a gold standard method is established, researchers should report the estimates resulting from both methods. Among all adherence predictors, socioeconomic status (SES) is widely considered to be prominent because of its associations with many factors theoretically affecting adherence such as economic, social, and education-related features. However, published studies have reported inconsistent results about the impact of SES on adherence. A systematic review of published studies examining predictors of antihypertensive medications adherence was performed. Almost half of studies reviewed neglected to measure SES; and in studies where SES was measured, income assessment was typically the only measure. Overall, only a minor association between SES and adherence was observed after pooling all available data (pooled adjusted risk estimate for non-adherence according to SES (high versus low) 0.89, 95% CI 0.87 to 0.92; p<0.001). It was hypothesized that the performance of adherence prediction models would improve if SES was represented using more comprehensive measures. A retrospective cohort of individuals who received a statin medication following discharge from a hospitalization for coronary heart disease was identified and followed for one year. Multi-domain measures did not improve the prediction performance of the population adherence model compared to single-domain measures. Overall, all SES measures examined had a very limited impact on prediction adherence. Supporting patients to adhere to their medications is a vital goal health care providers strive to achieve. Non-adherence to preventative medications is highly prevalent among patients surviving acute coronary syndrome (ACS). However, only few patients receive appropriate care after their ACS through support programs such as cardiac rehabilitation (CR). Because pharmacist’s interventions were shown to have beneficial impact on medication adherence in various settings, a streamlined pharmacist’s intervention in CR setting was investigated through a randomized clinical trial. The impact of this intervention was assessed through the proportion of patients who achieved optimal adherence. Although this proportion did not improve among the intervention group in comparison to the control group, an unexpected high prevalence of optimal adherence was obtained. A selection bias of highly motivated individuals in this study may explain this extraordinary adherence level. Results of the four independent research studies included in this dissertation provide novel insight relating to the factors, outcomes, and possible modalities to mitigate non-adherence in Canada. Further research is essential to help in relieving this major population health problem.






Doctor of Philosophy (Ph.D.)


Pharmacy and Nutrition





Part Of