Reliability and validity of the inertial sensor-based Timed “Up and Go” test in individuals affected by stroke

Abstract

Abstract-The instrumented Timed " Up and Go" test (iTUG) has the potential for playing an important role in providing clinically useful information regarding an individual's balance and mobility that cannot be derived from the original singleoutcome Timed "Up and Go" test protocol. The purpose of this study was to determine the reliability and validity of the iTUG using body-fixed inertial sensors in people affected by stroke. For test-retest reliability analysis, 14 individuals with stroke and 25 nondisabled elderly patients were assessed. For validity analysis, an age-matched comparison of 12 patients with stroke and 12 nondisabled controls was performed. Out of the 14 computed iTUG metrics, the majority showed excellent testretest reliability expressed by high intraclass correlation coefficients (range 0.431-0.994) together with low standard error of measurement and smallest detectable difference values. BlandAltman plots demonstrated good agreement between two repeated measurements. Significant differences between patients with stroke and nondisabled controls were found in 9 of 14 iTUG parameters analyzed. Consequently, these results warrant the future application of the inertial sensor-based iTUG for the assessment of physical deficits poststroke in longitudinal study designs.

Convergent Validity of a Wearable Sensor System for Measuring Sub-Task Performance during the Timed Up-and-Go Test

“…Wuest et al [15] found good test-retest reliability of IMU-based TUG metrics in patients with stroke, with ICC values generally above 0.9 for TUG sub-tasks with the exception of sit-to-walk (equivalent to our sit-to-stand sub-task) which had a poor reliability (0.4). This finding agreed with our data to some extent, as it was the longer 5 m test that experienced the lower sit-to-stand reliability in our study, and Wuest’s study used a 7 m TUG test.…”

“…Several groups have explored wearable sensors—IMUs specifically—as a potential approach for enabling the quantification of sub-task performance measures of the TUG and have demonstrated that these sensor-based metrics can discriminate between healthy controls and patient populations [10,11,12,13,14,15,20]. These devices have been shown to be useful for assessments in community dwelling seniors with dementia and/or history of falling when incorporated within a clinical protocol, such as a single- and dual-task paradigm [16,17,29].…”

“…Several recent studies [10,11,12,13,14,15,16] show that small unobtrusive inertial sensors (inertial measurement units, IMU), are capable of identifying the sub-tasks of the TUG, such as (1) sit-to-stand time; (2) walking time/speed (two walks); (3) turn time/rate (two turns); and (4) stand-to-sit time. Recent studies have explored quantitative TUG analysis in dual-task protocols that are of clinical interest in the study of dementia and falling [16,17].…”

Effect of cognitive task on components of 7 metertimed up-and-go test in persons with stroke

“…The instrumented timed-up and go (iTUG), APDM Mobility Lab system (APDM, Inc., Portland, USA), a set of portable inertial sensors and software were used to classify the components of 7 m TUG. The iTUG is reliable and valid to measure TUG performance in several group of patients with neurological diseases 16,20 . The iTUG has excellent testretest reliability (intraclass correlation coefficients range 0.43-0.99) and duration components of the TUG were valid to differentiate performance between patients with stroke and healthy persons 20 .…”

“…The iTUG is reliable and valid to measure TUG performance in several group of patients with neurological diseases 16,20 . The iTUG has excellent testretest reliability (intraclass correlation coefficients range 0.43-0.99) and duration components of the TUG were valid to differentiate performance between patients with stroke and healthy persons 20 . Six portable 3 dimensional inertial sensors were placed at mid-thoracic, 5th lumbar vertebra, bilateral wrists and ankles 21 A gyroscope ( ± 400°/s range) and accelerometer ( ± 5g range) captured angular velocity and acceleration at the sampling rate of 200 Hz 22 .…”