Impairment in activities of daily living and cognitive decline mediate the association between depressive symptoms and incident hip fractures in Chinese older adults.

ABSTRACT

BACKGROUND: The presence of depressive symptoms is associated with increasing risks of hip fractures (HFs). However, few studies investigated the longitudinal relationship between depressive symptoms and incident HFs among Chinese older adults, and the underlying mechanisms remain unclear. OBJECTIVES: To investigate the association between depressive symptoms and incident HFs, and the mediating role of cognitive function and impairment in activities of daily living (ADL) in the association among the older adults in China. METHODS: This population-based cohort study included 6336 Chinese older adults (age range, 60-101 years) without the history of HFs at baseline and with complete data during the follow-up. Discrete-time Cox regression was used to evaluate the relationship between depressive symptoms and incident HFs, and bootstrapped multiple mediation analyses were conducted to examine the effects of cognitive function and ADL impairment on the association. RESULTS: Among 6336 participants (3172 women [50.1%]; mean [SD] age, 67.9 [6.6] years), 264 (4.2%) subjects had HFs onset. After adjusting for age, sex, education, marital status, current residence, smoking status, drinking status, body mass index, number of chronic conditions, and falls history, elevated depressive symptoms were independently associated with increasing risks of HFs (adjusted hazard ratio [aHR] 1.42; 95% CI 1.07 to 1.88). However, this association was no longer significant (aHR 1.09; 95% CI 0.78 to 1.53) after adjusting for cognitive function and ADL impairment. When mortality and incident HFs were modeled as a composite outcome, the association between depressive symptoms and combined outcomes also remained non-significant after adjusting for cognitive function and ADL impairment. Furthermore, the mediation model demonstrated that cognitive decline (indirect effect ß = 0.002, 95% CI 0.001 to 0.003) and ADL impairment (indirect effect ß = 0.002, 95% CI 0.000 to 0.003) fully mediated the association between depressive symptoms and incident HFs after adjusting for age, sex, falls history, and number of chronic conditions. CONCLUSIONS: The positive association between depressive symptoms and incident HFs was confirmed among Chinese older adults, which was fully mediated by cognitive decline and ADL impairment. This study shed new light on the potential role played by depressive symptoms in incident HFs.