Impact of Social Frailty on Changes in Quality of Life and Health-Related Quality of Life among Middle-Aged and Older Adults: Findings from the Korean Longitudinal Study of Aging (2006–2022)

Purpose: This study examined the 16-year longitudinal impact of social frailty on quality of life (QoL) and health-related quality of life (HRQoL) among middle-aged and older adults. Methods: Data were obtained from the Korean Longitudinal Study of Aging (2006–2022), comprising 9,905 participants (6,003, aged 45–64 years; and 3,902, aged ≥65 years). Social frailty was assessed using five components: social support, social activity, social network, loneliness, and living alone. QoL and HRQoL were measured using self-reported satisfaction scales. Generalized estimating equations were applied to adjust for covariates. Results: Social frailty was prevalent among both middle-aged (44.6%) and older adults (60.1%) and was significantly associated with lower QoL and HRQoL. In longitudinal analyses, declines in QoL and HRQoL persisted throughout the follow-up period in older adults, whereas in middle-aged adults, the declines were significant only during the earlier years. In middle-aged adults, current smoking exerted a stronger negative impact on QoL and HRQoL (QoL: β=–4.33, p<.001; HRQoL: β=–2.89, p<.001), while in older adults, lack of regular exercise had a greater effect on HRQoL (β=–3.84, p<.001). Conclusion: Social frailty was associated with lower QoL and HRQoL across both age groups, with stronger and more persistent effects among older adults. Early interventions are needed during midlife, while sustained strategies are essential in later life. Age-specific approaches are crucial to promoting healthy aging.