Association between socioeconomic position trajectories and frailty among elderly people in Taiwan

This study examined the association between socioeconomic position (SEP) trajectories and frailty in the elderly population in Taiwan. We used data from people aged 53 years and over (n = 1284) collected from wave two of the Social Environment and Biomarkers of Aging Study. Frailty was identified using the modified Fried criteria, with the scores combined to use to categorize participants as frail (score = 3-5), prefrail (score = 1 or 2) and robust (score = 0). We applied a group-based person-centered trajectory model to identify four types of SEP trajectories (low-low, 19.2%; high-low 12.5%; low-high, 35.4%; and high-high, 32.9%) to describe the social mobility patterns in the participants' lives from childhood to older age. The mean age of the study population was 65.30 ± 8.94 years, and 47.39% of the participants were women. The prevalence of frailty was 18.39%. The low-low, high-low, low-high, and high-high SEP trajectory groups were represented by 37.92%, 24.93%, 15.43%, and 7.91%, respectively, of the study population. We used multinomial logistic regression models to evaluate the association between SEP and the risk of frailty. Compared with the low-low SEP trajectory group, the high-high SEP trajectory group was significantly associated with a lower prevalence of frail and pre-frail (odds ratios 0.17 and 0.36; 95% confidence interval 0.08-0.34 and 0.21-0.61). Our results suggest that a disadvantaged life-course SEP is associated with increased risks of frailty in older age. Avoiding that unfavourable SEP trajectories over the life course translate into an increased probability of frailty is key to reducing health inequalities in elderly populations.