Reliability of the thumb localizing test and its validity against quantitative measures with a robotic device in patients with hemiparetic stroke

Objectives: To examine the inter-rater reliability of the thumb localizing test (TLT) and its validity against quantitative measures of proprioception. Methods: The TLT was assessed by two raters in a standardized manner in 40 individuals with hemiparetic stroke. Inter-rater reliability was examined with weighted Kappa. For the quantitative measures, a bimanual matching task in a planar robotic device was performed. Without vision, each participant moved the unaffected hand to the perceived mirrored location of the affected hand, which was passively moved by the robot. Three measures were taken after 54 trials: Variability, trial-to-trial variability of the mirrored-matched locations; Area, the ratio of the area enclosed by the active hand relative to the passive hand; and Shift, systematic shifts between the passive and active hands. The correlation between the TLT and each robotic measure was examined with Spearman's rank correlation coefficient. Results: The overall weighted kappa of the TLT was 0.84 (P<0.001). The TLT correlated highly with Area (r = -0.71, P<0.001) and moderately with Variability (r = 0.40, P = 0.011). No significant correlation was found between the TLT and Shift. Conclusions: The TLT had a high inter-rater reliability, and was validated against quantitative measures of proprioception reflecting the perceived area of movement and variability of the limb location.