Replication of Sensor-Based Categorization of Upper-Limb Performance in Daily Life in People Post Stroke and Generalizability to Other Populations

Highlights: What are the main findings? A five-variable, five-cluster model was replicated in people with stroke and controls, and it generalized to musculoskeletal and other neurological conditions affecting the upper limb. Compared to clusters, two principal components and individual accelerometry variables showed higher convergent validity with self-report outcomes of upper limb performance and disability. What is the implication of the main finding? Upper limb performance in daily life, quantified by wearable movement sensors, may be better represented on a continuum of functional recovery, rather than with discrete categories. This application of wearable movement sensors supports a unified, data-driven approach to monitor upper limb recovery across conditions and severity of functional deficits in rehabilitation. Background: Wearable movement sensors can measure upper limb (UL) activity, but single variables may not capture the full picture. This study aimed to replicate prior work identifying five multivariate categories of UL activity performance in people with stroke and controls and expand those findings to other UL conditions. Methods: Demographic, self-report, and wearable sensor-based UL activity performance variables were collected from 324 participants (stroke n = 49, multiple sclerosis n = 19, distal UL fracture n = 40, proximal UL pain n = 55, post-breast cancer n = 23, control n = 138). Principal component (PC) analyses (12, 9, 7, or 5 accelerometry input variables) were followed by cluster analyses and numerous assessments of model fit across multiple subsets of the total sample. Results: Two PCs explained 70–90% variance: PC1 (overall UL activity performance) and PC2 (preferred-limb use). A five-variable, five-cluster model was optimal across samples. In comparison to clusters, two PCs and individual accelerometry variables showed higher convergent validity with self-report outcomes of UL activity performance and disability. Conclusions: A five-variable, five-cluster model was replicable and generalizable. Convergent validity data suggest that UL activity performance in daily life may be better conceptualized on a continuum, rather than categorically. These findings highlight a unified, data-driven approach to tracking functional changes across UL conditions and severity of functional deficits.