Inflammatory Biomarkers as Mediators between Chronic Diseases and Physical Functioning among Older Chinese Adults: A Longitudinal Mediational Analysis

Background: Little research has been conducted on the mediational role of inflammation on the asso-ciation between chronic diseases and physical functioning among older Chinese adults.Methods: Data were from the China Health and Retirement Longitudinal Study (CHARLS in 2011, 2015, and 2018). Chronic diseases were assessed by the summed scores of self-reported physician diagnosed of 14 chronic diseases in 2011. High-sensitivity C-reactive protein (CRP) and white blood cell (WBC) counts were used to measure inflammation in 2015. Physical functioning was measured by activities of daily living (ADLs) and instrumental activities of daily living (IADLs) in 2018. Longitudinal mediational models adjusting sex, age, residential areas, marital status, and health behaviors were used.Results: The sample size was 3,328 for CRP and 3,349 for WBCs, respectively. Chronic diseases in 2011 had direct effects on CRP in 2015 (b = 0.06, p < 0.001) and ADLs in 2018 (b = 0.25, p < 0.001), whereas the association between CRP and ADLs was not statistically significant (b = 0.07, p > 0.05). Higher number of chronic diseases were associated with higher levels of WBCs (b = 0.12, p < 0.001) and greater ADLs (b = 0.22, p < 0.001), and WBCs were also associated with greater ADLs (b = 0.04, p < 0.05). Similar results were found except that CRP was also associated with greater IADLs (b = 0.13, p < 0.001).Conclusion: Inflammatory biomarkers partially mediate the association between chronic diseases and physical functioning. A better understanding of the social and biological processes that lead to disability could potentially improve the health status of the Chinese adults in the future.Copyright (c) 2022, Taiwan Society of Geriatric Emergency & Critical Care Medicine.