Evaluation of upper limb function with digitizing tablet-based tests: reliability and discriminative validity in healthy persons and patients with neurological disorders

Abstract

Purpose To evaluate discriminative validity, relative reliability and absolute reliability of four tablet-based tests for the evaluation of upper limb motor function in healthy persons and patients with neurological disorders. Methods Cross-sectional study in 54 participants: 29 patients with upper limb movement impairment due to a neurological condition recruited from an inpatient rehabilitation centre and 25 healthy persons. Accuracy, speed and path length were analysed for four tablet-based tests: “Spiral drawings,” “Tapping,” “Follow the dot” and “Trace a star.” The area under the receiver operating characteristic curve (AUC) was used to evaluate discriminative validity. Relative reliability was analysed with the intra-class correlation coefficient (ICC), and absolute reliability by limits of agreement (LoA) and minimal detectable difference (MDD). Results All four tests showed excellent discriminative validity for the parameter accuracy (AUC 0.93–0.98). Tapping was the best test for discriminating patients from healthy persons. Test-retest reliability was good for accuracy in all tests (ICC = 0.76–0.88), but poor to moderate for speed and path length (ICC = 0.20–0.69). The MDD varied between 14% and 38%. Performance on the four tablet-based tests was stable between sessions, indicating that there was no learning effect. Conclusion The parameter accuracy showed excellent discriminative validity and reliability in all four tablet-based tests. Discriminative validity was excellent for all three parameters in the Tapping test. In the other tasks speed showed good to poor reliability, while the reliability of path-length was poor in all tasks. Results were comparable for the dominant and non-dominant hand. Tablet-based tests have the advantage that patients can use them for self-monitoring of upper limb motor function. Implications for rehabilitation Four tablet-based tests for the assessment of upper limb motor function in patients with upper limb neurological dysfunction were evaluated: “Spiral drawings”, “Tapping”, “Follow the dot” and “Trace a star”. The parameter accuracy in these four tests had excellent discriminative validity and good reliability. Patients can perform the tests independently at home for self-monitoring of progress. This may increase patients’ motivation to exercise at home. The results can be sent to physicians, enabling the earlier detection of deterioration, which may require medical attention.