Towards an approach of disability along a continuum from robustness, pre-frailty, frailty to disability

Background frailty and disability are very prevalent in older age and although both are distinct clinical entities, they are commonly used indistinctly in order to identify vulnerable older adults. Objective to propose a hierarchical indicator between frailty and disability among older adults along a single continuum. Design population-based cohort study. Setting the Bordeaux Three-City Study and the Aging Multidisciplinary Investigation (AMI) cohort. Subjects the sample included 1800 participants aged 65 and older. Methods an additive hierarchical indicator was proposed by combining the phenotype of frailty (robustness, pre-frailty and frailty), instrumental activities of daily living (IADL) and basic activities of daily living (ADL). To test the relevance of this indicator, we estimated the 4-year mortality risk associated with each stage of the indicator. Results in total, 34.0% were Robust (n = 612), 29.9% were Pre-frail (n = 538), 3.2% were Robust with IADL-disability (n = 58), 4.6% had pure Frailty (no disability) (n = 82), 11.9% were Pre-frail + IADL (n = 215), 8.6% were Frail + IADL (n = 154) and 7.8% Frail + IADL + ADL (n = 141). After grouping grades with similar mortality risks, we obtained a five-grade hierarchical indicator ranging from robustness to severe stage of the continuum. Each state presented a gradually increasing risk of dying compared to the robust group (from Hazard Ratio (HR) = 2.20 [1.49-3.25] to 15.10 [9.99-22.82]). Conclusions We confirmed that combining pre-frailty, frailty, IADL- and ADL-disability into a single indicator may improve our understanding of the aging process. Pre-frailty identified as the 'entry door' into the process may represent a key stage that could offer new opportunities for early, targeted, individualized and tailored interventions and care in clinical geriatrics.