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The bidirectional relationship between knee osteoarthritis and frailty in China: A longitudinal study
Ziwei Tian1, Huimin Zhao1, Yanping Zhai2
1College of Nursing, Shanxi University of Chinese Medicine, Jinzhong 030619, China.
Background:
Knee osteoarthritis is a common disease that causes disability and loss of independence in middle-aged and older adults, and may interact with frailty through shared pathways. Understanding their bidirectional relationship is clinically meaningful for early intervention. This study aimed to investigate the associations between knee osteoarthritis and frailty among middle-aged and older adults in China.
Methods:
The data for this study came from three waves (baseline 2011, follow-up 2013 and 2015) of the China Health and Retirement Longitudinal Study (CHARLS). A total of 3560 participants were included. Frailty was assessed with the Frailty Index. Knee osteoarthritis was defined as physician-diagnosed arthritis with self-reported knee pain. Longitudinal bidirectional relationships were found using cross-lagged panel models and random-intercept cross-lagged panel models.
Results:
A longitudinal bidirectional relationship between knee osteoarthritis and frailty was observed, with a stronger effect of frailty on subsequent knee osteoarthritis (Wald χ² = 11.416, P < 0.001). At the between-person level, individuals with knee osteoarthritis also tend to have a higher risk of frailty (β= 0.454, P < 0.001). At the within-person level, the predictive effect of knee osteoarthritis on frailty was significant only in the long term (β=0.055, P < 0.05). Subgroup analyses showed that this longitudinal bidirectional relationship was particularly strong among females as well as those with low education levels.
Conclusions:
This study reveals a longitudinal bidirectional relationship between knee osteoarthritis and frailty in middle-aged and older adults. In particular, the dominant role of frailty in the development of knee osteoarthritis was found, as well as the negative impact of knee osteoarthritis accumulation on frailty over time. This result suggests that targeting frailty early interventions in an ageing society may help to interrupt the vicious cycle of knee osteoarthritis and reduce the risk of disability. It provides a scientific basis for public health strategies.
