Associations of Sleep Quality and Frailty among the Older Adults with Chronic Disease in China: The Mediation Effect of Psychological Distress.

Frailty affects the elderly and leads to adverse health outcomes. Preliminary evaluations have suggested that sleep quality and psychological distress are predictors of frailty among older adults. However, the mechanisms by which sleep quality affect frailty had not been fully addressed in the previous research. This study aimed to explore the mediation effect of psychological distress on the association between sleep quality and frailty among the elderly with chronic diseases in rural China. A total of 2346 old adults were included in the analysis. Frailty status was measured by Fried Phenotype criteria. Sleep quality was assessed by Pittsburgh Sleep Quality Index (PSQI), and psychological distress was examined by Kessler Psychological Distress Scale (K10). Ordinal logistic regressions were performed to assess the relationships between sleep quality and frailty. Mediation test was also conducted by bootstrap method. The prevalence rate of frailty among the elderly with chronic diseases was 21% in rural China. Compared with the elder of robust status, respondents identified as having frailty have lower SES, less vigorous physical activity, and worse self-reported health status. Poor sleep quality was a significant predictor of frailty with mediators (OR = 1.44, 95% CI = 1.19-1.76). Mediation analysis suggested that psychological distress mediated 41.81% of total effect between sleep quality and frailty. This study indicated that poor sleep quality was significantly related to frailty, and psychological was a mediator of this association. However, we could not investigate causal relationships between variables since this was one cross-sectional study. These findings suggested that an early detection of sleep problems and also psychological disorders should be taken to prevent frailty among the rural older adults in China.