Background It has been hypothesised that frailty is the root cause of clinically observed but rarely systematically measured unstable disability among older adults. In this study, we measure the extent of short-term disability fluctuations and estimate their association with frailty using intensive longitudinal data. Methods Repeated measurements of disability were collected under a measurement burst design in the FRequent health Assessment In Later life (FRAIL70+) study. A total of 426 community-dwelling older adults (70+) in Austria were interviewed about difficulties with basic, instrumental and mobility-related activities of daily living biweekly up to a total of 14 times in two measurement bursts (2891 and 2192 observations). Baseline frailty was assessed with both physical frailty (FP) and the frailty index (FI). Disability fluctuations were measured with the intra-individual interquartile range (iIQR) and estimated with a two-step generalised mixed regression procedure. Results Fewer participants were frail at baseline according to FP (11%) than FI (32%). Frail study participants reported not only more severe disability but also had more short-term disability fluctuations (iIQR = 1.0–1.5) compared with their robust counterparts (iIQR = 0). Regression models indicated that baseline frailty was associated with 2–3 times larger short-term disability fluctuations, which were also more prevalent among women, and increased with age and disability severity. Conclusion Compared with those who were robust, frail older adults were characterised by not only more severe but also more unstable disability. Short-term disability fluctuations are closely tied to disability severity. Future studies should assess both stressors that may cause disability fluctuations among frail older adults as well as their potential consequences to inform frailty-centred care.

中文翻译：

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重新审视不稳定的残疾和虚弱的波动：一种测量爆发法


背景 据推测，虚弱是临床观察到但很少系统测量的老年人不稳定残疾的根本原因。在这项研究中，我们测量了短期残疾波动的程度，并使用密集的纵向数据估计它们与虚弱的关联。方法 在 FRequent health Assessment In Later life （FRAIL70+） 研究中，根据测量突发设计收集残疾的重复测量值。奥地利共有 426 名社区居住的老年人 （70+） 接受了关于日常生活中基本、工具和行动相关活动困难的采访，每两周一次，在两次测量爆发中总共采访了 14 次（2891 次和 2192 次观察）。使用身体虚弱 （FP） 和虚弱指数 （FI） 评估基线虚弱。残疾波动用个体内四分位距 （iIQR） 测量，并使用两步广义混合回归程序估计。结果 根据 FP （11%） 的基线虚弱参与者少于 FI （32%）。与强壮的受试者 （iIQR = 0） 相比，虚弱的研究参与者不仅报告了更严重的残疾，而且短期残疾波动也更多 （iIQR = 1.0-1.5）。回归模型表明，基线虚弱与大 2-3 倍的短期残疾波动相关，这种波动在女性中也更为普遍，并且随着年龄和残疾严重程度的增加而增加。结论 与体格健壮的老年人相比，虚弱的老年人不仅表现为更严重的残疾，而且表现为更不稳定的残疾。短期残疾波动与残疾严重程度密切相关。 未来的研究应评估可能导致虚弱老年人残疾波动的压力源及其潜在后果，以便为以虚弱为中心的护理提供信息。