The FIT–FRAIL–DISABLE Framework: A Multidimensional CGA-Based Model for Proportional Treatment of Older Adults Across Speciality Care

Frailty, cognitive impairment, depression, functional dependency, low physical performance, and undernutrition are highly prevalent in older adults referred for cancer treatment, cardiovascular interventions, neurological therapies, and orthopaedic surgery, and each independently predicts treatment toxicity, post-procedural complications, and mortality. Comprehensive Geriatric Assessment (CGA) is the most accurate predictor of treatment outcomes in older patients, yet it remains structurally absent from most speciality pathways, contributing to overtreatment of biologically frail patients and undertreatment of biologically robust ones. In this Viewpoint, we propose and operationalise the FIT–FRAIL–DISABLE multidimensional geriatric stratification model as a conceptual framework for translating CGA findings into proportional, speciality-specific treatment recommendations across oncology, cardiology, neurogeriatrics, and orthogeriatrics. The model integrates six validated CGA instruments—the Mini-Mental State Examination (MMSE), the 15-item Geriatric Depression Scale (GDS-15), basic and instrumental Activities of Daily Living (ADL, IADL), the Short Physical Performance Battery (SPPB), and the Mini Nutritional Assessment Short Form (MNA-SF)—into three actionable categories (FIT, FRAIL, DISABLE) aligned with full-intensity, risk-adapted, and symptom-focused care, and is explicitly positioned in relation to the deficit-based frailty paradigm and the WHO Intrinsic Capacity (ICOPE) framework, which it complements rather than replaces. We specify a provisional, a priori decision rule for combining domain scores and describe how each stratification category should inform—but not dictate—goal-concordant treatment intensity within a shared decision-making process. FIT–FRAIL–DISABLE is presented as a proposed, hypothesis-generating framework: its composite thresholds and domain weighting have not yet been empirically derived, and the model has not undergone prospective validation. Retrospective calibration on existing CGA cohorts and prospective multicentre validation are being designed within the GERIA-NET research consortium. If validated, the framework has the potential to reduce both overtreatment-related harm and undertreatment-related therapeutic deprivation in older adults undergoing active treatment.