Association between pain, sleep and intrinsic capacity in Chinese older adults: Evidence from CHARLS

OBJECTIVES: To examine the relationship between pain, sleep, and intrinsic capacity (IC). DESIGN: A cohort study. SETTING AND PARTICIPANTS: Data were obtained from participants in China Health and Retirement Longitudinal Study (CHARLS) 2011-2015. The study population consisted of older adults who completed assessments on pain, sleep duration, sleep quality and IC at baseline. MEASUREMENTS: Pain, sleep duration, and sleep quality were assessed through self-reports from participants. The total IC score was derived from five domains: psychological, sensory, cognitive, locomotor, and vitality. The relationships between pain, sleep duration, sleep quality and IC were analyzed using linear mixed models. The relationship between sleep duration and IC was analyzed using quadratic analysis. Stratified analyses by gender and age were also performed. RESULTS: A total of 3517 participants were included in the analysis. After adjusting for all covariates, single-site pain (β = -0.29, 95% confidence interval [CI] = -0.38 to -0.20) and multisite pain (β = -0.41, 95% CI = -0.48 to -0.34) were significantly associated with a decrease in IC compared with older adults without pain; long sleep duration (β = -0.15, 95% CI = -0.24 to -0.06) was significantly associated with a decrease in IC compared with older adults with moderate sleep duration; and poor sleep quality (β = -0.63, 95% CI = -0.71 to -0.55) and fair sleep quality (β = -0.33, 95% CI = -0.40 to -0.27) were significantly associated with a decrease in IC compared with older adults with good sleep quality. CONCLUSION: To maintain IC, it is important to ensure approximately 7.5 h of sleep duration, improve sleep quality, and manage pain. Interventions should begin as early as possible.