LAUSR

BACKGROUND frailty fluctuations, that is, within-person up and down deviations from individual long-term frailty index trajectories represent a hitherto both conceptually and empirically untapped facet of frailty among older adults. OBJECTIVE to assess the size of frailty fluctuations in old age and their association with frailty levels, frailty growth as well as sex and socio-economic position. METHODS a total of 18,704 biannual observations from 4,514 community-dwelling older adults (65+) in 10 European countries over 12 years from the Survey of Health, Ageing and Retirement in Europe (SHARE) were analysed. A frailty index was constructed based on 50 items. Long-term frailty trajectories and fluctuations were modelled simultaneously using Bayesian mixed-effects location-scale regression models. RESULTS frailty index fluctuations were non-negligible among older adults, amounting to 0.04/0.05 FI or 2.0/2.5 health deficits on average. 30% of fluctuations were between 0.04 and 0.1 FI (2 and 5 health deficits) and 8% were larger than 0.1 FI (5 health deficits). Fluctuations increased with age and frailty levels, and were higher among women, those with low socio-economic position (education) and individuals who died during follow-up. CONCLUSIONS frailty index fluctuations refer to instabilities in an older person's health status and represent a hitherto untapped but relevant aspect of vulnerability in old age. Future analysis of frailty fluctuations should be based on a larger number of repeated observations with shorter time intervals.