Circadian syndrome and frailty transition among older adults: longitudinal evidence from two national aging cohorts

Circadian syndrome (CircS) has been associated with higher prevalence of frailty. However, the relationships of CircS and its changes with the risk of frailty and transitions between frailty states remain unclear. To address the knowledge gaps, we utilized data from two ongoing national aging cohorts, the China Health and Retirement Longitudinal Study (CHARLS) and the English Longitudinal Study of Ageing (ELSA), to: 1) examine the association between baseline CircS and frailty incident risk and transitions; and 2) evaluate the relationship between longitudinal changes in CircS and frailty incident risk over time.