Objective: To evaluate the sensitivity of digital biomarkers of bradykinesia to longitudinal progression relative to MDS-UPDRS sub-scores in early-stage Parkinson’s disease (PD).

Background: It is unknown whether digital health technologies (DHTs) can be used to monitor the progression of bradykinesia in early PD. To this end, we instrumented patients with inertial sensors during performance of upper and lower body bradykinesia assessments at routine clinic visits over the course of a one-year longitudinal study (WATCH-PD). Digital features of bradykinesia were compared to contemporaneously collected MDS-UPDRS clinician ratings.

Method: 82 de-novo PD patients and 50 healthy participants wore inertial sensors during completion of MDS-UPDRS Part 3 assessments at baseline, 1, 3, 6, 9, and 12 months. Signal features related to speed, amplitude, rhythm, slowing of movement, and decrementing amplitude were derived using a heuristic, signal processing approach. Dimensionality was reduced by generating composite scores for pronation-supination and toe-tapping using Z-score summation. Wilcoxon signed-rank tests were used to evaluate known groups validity and sensitivity to longitudinal change. Kruskal-Wallis tests were used to evaluate clinical validity of digital features alongside appropriate MDS-UPDRS sub-scores. Intraclass correlation coefficients were used to evaluate test-retest reliability in healthy and PD participants.

Results: Digital composites for both pronation-supination (p=0.028) and toe-tapping (p=0.011) showed sensitivity to 1 year progression whereas corresponding MDS-UPDRS items 3.6 and 3.7 did not (p>0.62). Both MDS-UPDRS pronation-supination (p<0.001) and toe-tapping (p<0.001) and digital composite measures of pronation-supination (p<0.001) and toe-tapping (p=0.029) significantly distinguished between PD patients and healthy volunteers. Digital composite measures of pronation-supination (p=0.034) and toe-tapping (p=0.001) both demonstrated strong relationships with severity as measured by MDS-UPDRS items 3.6 and 3.7

Conclusion: Our results demonstrate potential value of DHTs to enhance sensitivity to disease progression in early PD. Further work investigating digital measurement of bradykinesia and other cardinal symptoms of PD is underway and will be used fully evaluate the utility of DHTs as monitoring or response digital biomarkers.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/enhanced-sensitivity-to-bradykinesia-progression-using-digital-health-technologies-in-early-parkinsons-disease/