Factors Influencing Outcomes of Heart Failure: A Population Health Approach

Background: Symptomatic heart failure is a chronic and disabling condition that affects over 350 000 Canadians and is characterized by inevitable progression. Historically, research on the ways to increase survival has focused on biomedical factors. However, the continued poor prognosis of heart failure has prompted the search for other ways to improve the lives of these patients. Research in other chronic conditions demonstrates that social circumstances, described collectively as individual social interactions (e.g. social support, social participation) and community social factors (e.g. social capital, social norms), can influence health outcomes. Purpose: The purpose of this research was to describe and assess the impact of selected social circumstances potentially related to heart failure outcomes. Methods: Two literature reviews and one empirical study were performed. Conceptual models were proposed to describe the hypothesized pathways between selected social circumstances and heart failure outcomes. The first review was a systematic review of quantitative studies evaluating the relationship between social support and both rehospitalization and death. The review included a critical analysis of the methods employed by previous studies. The second review integrated the qualitative and quantitative literature describing the relationship between individual social interactions (including support, roles and participation) and the quality of life of patients or experience of living with heart failure. A narrative summary was provided and an integration of findings from both qualitative and quantitative study designs was performed. In the empirical study, patients‘ demographic and clinical information was examined simultaneously with selected community factors in a multilevel analysis. Outcomes of interest included rehospitalization or death of heart failure patients. Results: The systematic review shows that previous quantitative research has linked social support to reduced rehospitalization, but there is little evidence to link it with prolonged survival. The critique of the methods describes an inadequate conceptualization and inconsistent measurement of social support. A conceptual model showing how social support can influence rehospitalization is proposed. The integrative review presents qualitative research that identified the following social interactions as important components of the heart failure experience: social support, social participation and role fulfillment. However, no quantitative relationship between social support and quality of life was found. The potential reasons for the discrepant findings between the qualitative and quantitative studies include: the focus on social support as the only component of social interactions assessed in the quantitative literature; and the inconsistent measurement of social support. A conceptual model is presented to describe the multiple components of social interactions and the theoretical basis for their effects. The multilevel analysis demonstrates that individual factors exerted the strongest effect on heart failure outcomes in most models. Community characteristics had little influence on rehospitalization or death. Study design and analysis issues are proposed to explain these findings. Conclusion: The literature reviews and the empirical study provide a contribution to the population health literature, offering a broad approach to assessing the determinants of disease progression in heart failure patients. This thesis research advances the discussion about which social circumstances may influence heart failure outcomes and their pathways. The use of the proposed conceptual models in future research will help clarify the role of social circumstances in the prognosis of heart failure