Understanding the Role of Loneliness in Population Health Outcomes and Health Care Utilisation

Abstract

Loneliness, shaped by biological, personal, and environmental factors, is increasingly recognised for its impact on health. Despite extensive literature, causal evidence linking loneliness, its determinants, and health outcomes remains limited. This thesis investigates the independent long-term effect of loneliness on health and mortality while exploring community and societal factors that influence loneliness. It also examines the potential for intervention and prevention to reduce loneliness and alleviate its economic impact. Chapter 3 includes a study of cross-country comparisons to understand the causal effect of retirement on loneliness across cultures with similarities and differences in macro-level determinants. Chapter 4 identified longitudinal trajectories of loneliness among middle-aged and Australian women and examined predictors of these trajectories and their associations with health-related quality of life (HRQoL). Chapter 5 explored the causal effects of persistent and chronic loneliness on mortality among Australian women, estimated using targeted maximum likelihood estimation. Finally, Chapter 6 involved a systematic review and meta-analysis of the effect of psychosocial interventions on healthcare utilisation and social well-being. Altogether, our research indicates that loneliness determinants may vary depending on cultural norms and geographical regions. Additionally, long-term patterns of loneliness are negatively associated with HRQoL and increase the risk of mortality. Finally, our findings reveal that psychosocial interventions can increase social well-being and simultaneously decrease healthcare utilisation across different population groups and countries. These findings imply that loneliness is a significant social determinant of health with serious health and economic implications. Therefore, addressing social health should be prioritised from a public health standpoint, on par with the prevention of physical and mental health issues.