Development and validation of an automated Trunk Impairment Scale 2.0 scoring system using rule-based classification

The Trunk Impairment Scale Version 2.0 (TIS 2.0) measures the motor impairment of the trunk after a stroke through the evaluation of dynamic sitting balance and co-ordination of trunk movement. Evaluations by physiotherapists depend on their ability in detecting minor changes in motion and observing limb movements and these can be time consuming and reduce their availability for rehabilitation work. An automated scoring system for TIS 2.0 was proposed to provide a more reproducible and standardized alternative to manual physiotherapist assessments. In the development phase, motion data from lay actors simulating stroke condition were collected using video motion capture system OpenCap. This data was utilized to create metrics and establish cut-off values for a rule-based classification. The discriminant abilities of the metrics were evaluated using the area under the curve (AUC). In the testing phase, the performance of the developed system was assessed on 19 stroke survivors (Berg Balance Scale score of 20-55) using both automated system and manual scoring by nine physiotherapists. The discriminant abilities of the features used in the dynamic sitting balance subscale are considered excellent to outstanding (AUC ≥ 0.717), and coordination subscale ranged from poor to outstanding (AUC ≥ 0.667). The automated scores aligned with physiotherapists' scores, achieving an average percentage of agreement 71.1%. The total TIS 2.0 scores generated by the automated method showed moderate correlation with the sum of mode-determined task scores (R = 0.526, p < 0.05). These findings suggest that the proposed automated system demonstrates comparable validity to assessments by physiotherapists.