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.