Sensor based assessment of turning during instrumented Timed Up and Go Test for quantifying mobility in chronic stroke patients

BACKGROUND: Turning may be particularly challenging for stroke patients leading to decreased mobility and increased functional restriction. Timed up and go instrumentation using a simple technology in the clinical context could allow for the collection of both traditional and potentially more discriminatory variables in turning ability. AIM: Determine whether the speed turning metrics obtained by a single inertial sensor are suitable for differentiating between stroke patients with varying levels of mobility and disability. DESIGN: Cross-sectional study. SETTING: Outpatients setting. POPULATION: Chronic stroke patients. METHODS: A total of 48 chronic stroke patients and 23 healthy controls were included. Stroke patients were divided in two groups based on the total iTUG score: an impaired mobility (> 20 seconds) and an available mobility (<20 seconds) group. All subjects performed an instrumented Timed Up and Go (iTUG) wearing a single IMU sensor on the lower back. Time of subcomponents of the timed up and go test and kinematic parameters of turning were quantified. Other clinical outcomes were: 10 meters walk test, Functional Ambulation Categories Scale (FAC), the Rivermead Mobility Index (RMI), Modified Rankin Scale and the Saltin–Grimby Physical Activity Level Scale (SGPALS). RESULTS: There were significant differences (P<0.01) in iTUG phases and turning speeds among groups. Low to strong significant correlations were found between measures derived from the turning speeds and clinical measures. The area under the curve (AUC) of Receiver Operating Characteristic (ROC) turning speeds was demonstrated to be able to discriminate (AUC: 0.742-0.912) from available to impaired stroke patients. CONCLUSIONS: This study provides evidence that turning speeds during timed up and go test are accurate measures of mobility and capable of discriminating stroke patients with impaired mobility from those with normal mobility. CLINICAL REHABILITATION IMPACT: The turning metrics are related to impairment and mobility in chronic stroke patients; hence they are important to include during clinical evaluation and may assist in creating a customized strategy, assess potential treatments, and effectively organize recovery.