Objective: Characterize specific motor signs and their impact on the daily life of people with early-stage Parkinson’s disease (PD) before initiation of symptomatic treatment (ST) using MDS-UPDRS parts II and III.

Background: Understanding the specific signs and symptoms experienced by people with early-stage PD before receiving ST is required to document disease progression.

Method: Data across a set of 21 MDS-UPDRS part III items related to bradykinesia, rigidity and rest tremor (clinically relevant for early-stage PD) and 5 daily life activity items from part II were extracted from the Parkinson’s Progression Markers Initiative de novo PD cohort (n=423). A cross-sectional Rasch model was applied to the part III item set to determine if it formed an adequate measure of motor signs for early-stage PD. Part II items were then mapped onto the measure of motor signs of early-stage PD to illustrate the relationship between motor signs and impacted daily life activities.

Results: Rasch model analysis of 21 selected MDS-UPDRS part III items showed the rest tremor items did not fit well with the bradykinesia and rigidity items. In contrast, the Rasch model of 15 items related to bradykinesia and rigidity showed good performance. Items adequately targeted to study sample (no floor or ceiling effect), despite an item coverage gap towards the milder end of motor signs of early-stage PD. When ordered based on the Rasch model, items defined a meaningful severity continuum, providing supportive evidence for the validity of the scale: signs of bradykinesia and rigidity showed first in the ipsilateral upper limb, second in the ipsilateral lower limb, and finally in the contralateral limbs. Response scale and reliability were adequate. Mapping showed impact on daily life activities may start being reported when bradykinesia and rigidity get documented for the contralateral side of the body, i.e., when early-stage PD manifestations become bilateral. Handwriting was the only of these items for which “slight” impairment was typically reported before that point.

Conclusion: A sub-score of 15 MDS-UPDRS part III items focusing on the severity of bradykinesia and rigidity demonstrated good measurement properties in patients with early-stage PD prior to ST, despite some limitations in terms of coverage of mild severity. Bilaterality may be a milestone in early-stage PD progression.

« Back to 2023 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/repurposing-the-mds-updrs-part-iii-for-early-stage-parkinsons-disease-supportive-evidence-for-a-bradykinesia-and-rigidity-specific-sub-score/