Chronic pain as a mediator in the falls-frailty association: Evidence from middle-aged and older ethnic minorities in Yunnan, China.

Background: Falls are associated with an increased risk of frailty in middle-aged and older adults; however, the mediating role between falls and frailty remains underexplored, particularly among ethnic minority groups with distinct sociocultural and environmental exposures. Ethnic minority populations exhibit significant disparities in the prevalence of falls, frailty, and chronic pain compared to the majority. The primary objective of this study is to examine the relationship between falls and frailty in middle-aged and elderly individuals residing in Yunnan Province, China, with a specific emphasis on exploring the potential mediating effect of chronic pain across different ethnic groups.

Methods: Employing a cross-sectional design, data were collected from July to December 2022 from adults aged ≥45 years in five ethnically diverse counties of Yunnan Province, China. Structured face-to-face interviews and stratified multistage cluster sampling were used for data collection. Baron and Kenny's causal steps method was used to explore the mediating effect of chronic pain on the relationship between falls and frailty. Spearman correlation analysis, multiple linear regression models, and bootstrap method were used for data analysis.

Results: A total of 2710 respondents participated in this study. The age distribution was as follows: 1161 (42.84 %) aged 45-59 years, 863 (31.85 %) aged 60-69 years, and 686 (25.31 %) aged 70 years or older. The sample comprised 1218 males (44.94 %) and 1492 females (55.06 %). The prevalence of falls among middle-aged and older individuals was 12.77 %, while the prevalence of frailty in the same population was observed to be 21.62 %. Spearman correlation analysis revealed significant positive association between chronic pain and both falls (r = 0.135, P < 0.05) as well as frailty (r = 0.383, P < 0.05). Frailty also exhibited a significant positive correlation with falls (r = 0.162, P < 0.05). After adjusting for all covariates, the total effect of falls on frailty was estimated to be 1.065 (95 % bootstrap CI: 0.804∼1.326), with a direct effect estimate of 0.797 (95 % bootstrap CI: 0.511∼1.083). The indirect effect of chronic pain on this association was found to be approximately one-quarter at 0.268 (95 % bootstrap CI: 0.170∼0.366). The subgroup analysis discovered differences in the mediating effects across different ethnic groups; specifically, the proportions mediated by chronic pain were found to be 28.2 %, 18.4 %, and 21.5 % for Han majority group, Zhiguo ethnic minorities, and other ethnic minority groups, respectively.

Conclusion: This study provides valuable insights into the intricate association between frailty, falls, and chronic pain among middle-aged and older adults from diverse ethnic backgrounds in a western province of China. Effective management strategies targeting chronic pain and falls prevention could serve as crucial interventions to address frailty.