Objective: To evaluate reliability and responsiveness of an objective app-based bradykinesia assessment tool in the clinic and at home and to compare it to clinical ratings.

Background: Rating of bradykinesia is challenging as it combines several features (speed impairment, amplitude reduction, fatiguing, hesitations, arrests in movement) into a single score. Additionally, clinical assessment does not permit capture of symptom fluctuation throughout the day in response to treatment. We have developed a motion sensor-based tablet app to provide objective symptom ratings with improved resolution.

Methods: Thirty-two patients with Parkinson’s disease (Table 1) treated with subthalamic deep brain stimulation (DBS) were recruited. Subjects arrived at the clinic with DBS on and were outfitted with a motion sensor on the index finger of the more affected hand to perform UPDRS-directed finger-tapping, hand opening-closing, and pronation-supination tasks, while being videoed for subsequent blinded clinician scoring. Tasks were repeated to examine test-retest reliability. DBS was turned off and two repetitions of tasks were performed 10, 20, and 30 minutes after turning DBS off. Time points were compared using Tukey’s honestly significant difference procedure with an alpha of 0.05 to examine responsiveness. Participants were then sent home with an app-based system to perform the same tasks six times per day spaced two hours apart, three days per week, for two weeks. As in the clinic, the tasks were performed twice. Intraclass correlation (ICC) and minimal detectable change (MDC) were calculated between repetitions for ratings given by clinicians and the motion sensor system.

Results: As DBS wore off, motion sensors detected worsening of amplitude scores sooner than did clinicians. Additionally, motion sensors detected significant continued worsening of symptoms at several time points after turning DBS off, while clinician ratings only detected significant worsening compared to the DBS on state. Participants performed the motor tasks as instructed at home 99.1% of the time. Average ICCs and MDCs are shown in Table 2.

Conclusions: The tablet app demonstrates improved reliability and responsiveness in capturing bradykinesia in both the clinic and at home compared to clinician ratings and is associated with excellent home compliance, which could aid in the evaluation of therapies and improve patient care.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/reliability-and-responsiveness-of-in-clinic-and-at-home-app-based-bradykinesia-assessment/