Frailty in Older Adults in China -Trajectories, Determinants, and Impacts on Healthcare Utilization and Mortality

Abstract

Frailty, though not a disease in itself, often precedes the onset of illness and is frequently overlooked. Research has paid insufficient attention to frailty as a dynamic phenomenon, particularly its longitudinal changes. This thesis aims to enhance our understanding of frailty trajectories, their early life determinants, and the impact of frailty changes on healthcare utilization and mortality among older adults in China. This thesis utilizes data from the China Health and Retirement Longitudinal Study (CHARLS) and the WHO Study on Global AGEing and Adult Health (SAGE). The analytical methods employed include the Group-Based Trajectory Models (GBTM) (Paper I), causal mediation analysis (Paper II), joint modeling (Paper III), and Random Intercept Cross-Lagged Panel Models (RI-CLPM) (Paper IV). Paper I identified three distinct frailty trajectories. A rapid frailty progression was associated with older age, female sex, low education attainment, rural residency, low physical activity, and residence in Northeast China. Paper II found a significant relationship between childhood socioeconomic position and the progression of frailty in later life, which is partly mediated by adult socioeconomic position. Paper III identified a significant association between frailty index and long-term mortality risk. When stratified by age, change in frailty index was significantly associated with all-cause mortality risk only for those over 75 years. Paper IV suggests a bidirectional causal relationship between frailty and healthcare utilization. To develop targeted interventions and policies that address the unique challenges faced by vulnerable populations, it is essential to consider the heterogeneity in the progression of frailty and the influence of childhood socioeconomic position. Additionally, our study suggests that regular geriatric frailty assessments and screenings should be conducted with varying frequency based on age, optimizing the use of limited healthcare resources while effectively enhancing health outcomes.