From continuous signals to accountable care: a trajectory-based framework for wearable monitoring in older adults

Wearable technologies can continuously measure cardiovascular, physiological, and behavioral signals outside clinical settings, but more measurement does not necessarily produce better care. This limitation is particularly important in older adults, in whom frailty, multimorbidity, polypharmacy, cognitive impairment, altered vascular physiology, and caregiver dependence modify both signal reliability and clinical meaning. We argue that wearable monitoring in later life should move from population thresholds toward individualized physiological trajectories and from automated alerts toward accountable clinical action. We propose a trajectory-to-action framework based on five elements: individual baseline, within-person deviation, multimodal concordance, geriatric contextualization, and predefined clinical response. The framework is conceptual and has not been prospectively validated; its clinical utility, safety, implementation feasibility, and impact on outcomes require prospective testing. In this model, an alert is not a diagnosis but a request for attention whose recipient, response time, confirmatory pathway, and escalation rules are established in advance. Evaluation should therefore extend beyond sensor accuracy to include actionability, alert burden, clinical utility, equity, and net benefit. We propose that wearable monitoring in older adults should be evaluated by whether continuous signals can be translated into proportionate, context-aware, and accountable care.