Construct validity and responsiveness of clinical upper limb measures and sensor-based arm use within the first year after stroke: a longitudinal cohort study

Abstract Background: Concurrent validity and responsiveness of upper limb outcome measures are essential to interpret motor recovery poststroke. Evaluating the associations between clinical upper limb measures and sensor-based arm use (AU) fosters a comprehensive understanding of motor recovery. Defining sensor-based AU metrics for intentional upper limb movements could be crucial in mitigating bias arising from walking-related activities. Here, we investigate the measurement properties of a comprehensive set of clinical measures and sensor-based AU metrics when gait and non-functional upper limb movements are excluded. Methods: In a prospective, longitudinal cohort study, individuals with motor impairment were measured at days 3±2 (D3), 10±2 (D10), 28±4 (D28), 90±7 (D90), and 365±14 (D365) after their first stroke. Upper limb function, activity capacity, and performance were assessed using the Fugl-Meyer Assessment, Action Research Arm Test, Box & Block Test, and the 14-item Motor Activity Log. For three days, individuals wore five movement sensors (trunk, wrists, and ankles). Thirteen AU metrics were computed based on functional movements during non-walking periods. Concurrent validity across clinical and AU metrics was determined by Spearman's rank correlations for each time point. Criterion-based responsiveness was examined by correlating patient-reported Global Rating of Perceived Change (GRPC) scores (1-7) and observed change in upper limb outcome. Optimal cut-off values for minimal important change (MIC) were estimated by ROC curve analysis. Results: Ninety-three individuals participated. At D3 and D10, correlations between clinical measures and AU-metrics presented variability (range rs 0.44-0.90, p<0.01). All time points following showed strong positive associations between capacity measures and affected AU metrics (range rs 0.73-0.94, p<0.01), whereas unilateral nonaffected AU metrics had low-to-high negative associations (range rs 0.48-0.77). Responsiveness across outcomes was highest between D10-D28 within moderate-to-strong relations between GRPC and clinical measures (rs range 0.60-0.73, p<0.01), whereas relations were weaker for AU-metrics (rs range 0.28-0.43, p<0.05). Eight MIC values were estimated for clinical measures and nine for AU metrics, showing moderate to good accuracy (66-87%). Conclusions: We present reference data on concurrent validity and responsiveness of clinical upper limb measures and specified AU metrics within the first year poststroke. Estimated MIC values can be used as a benchmark for clinical stroke rehabilitation. Trial registration: This trial was registered on clinicaltrials.gov; registration number NCT03522519.