Frontiers in Neurology (Sep 2021)

Stability of MDS-UPDRS Motor Subtypes Over Three Years in Early Parkinson's Disease

  • Abhijeet K. Kohat,
  • Abhijeet K. Kohat,
  • Samuel Y. E. Ng,
  • Samuel Y. E. Ng,
  • Aidan S. Y. Wong,
  • Aidan S. Y. Wong,
  • Nicole S. Y. Chia,
  • Nicole S. Y. Chia,
  • Xinyi Choi,
  • Xinyi Choi,
  • Dede L. Heng,
  • Dede L. Heng,
  • Wei Li,
  • Wei Li,
  • Hwee-Lan Ng,
  • Hwee-Lan Ng,
  • Shu-Ting Chua,
  • Shu-Ting Chua,
  • Shermyn X. M. Neo,
  • Shermyn X. M. Neo,
  • Zheyu Xu,
  • Zheyu Xu,
  • Kay-Yaw Tay,
  • Kay-Yaw Tay,
  • Kay-Yaw Tay,
  • Wing-Lok Au,
  • Wing-Lok Au,
  • Wing-Lok Au,
  • Eng-King Tan,
  • Eng-King Tan,
  • Eng-King Tan,
  • Louis C. S. Tan,
  • Louis C. S. Tan,
  • Louis C. S. Tan

DOI
https://doi.org/10.3389/fneur.2021.704906
Journal volume & issue
Vol. 12

Abstract

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Background: Various classifications have been proposed to subtype Parkinson's disease (PD) based on their motor phenotypes. However, the stability of these subtypes has not been properly evaluated.Objective: The goal of this study was to understand the distribution of PD motor subtypes, their stability over time, and baseline factors that predicted subtype stability.Methods: Participants (n = 170) from two prospective cohorts were included: the Early PD Longitudinal Singapore (PALS) study and the National Neuroscience Institute Movement Disorders Database. Early PD patients were classified into tremor-dominant (TD), postural instability and gait difficulty (PIGD), and indeterminate subtypes according to the Movement Disorder Society's Unified PD Rating Scale (MDS-UPDRS) criteria and clinically evaluated for three consecutive years.Results: At baseline, 60.6% patients were TD, 12.4% patients were indeterminate, and 27.1% patients were PIGD subtypes (p < 0.05). After 3 years, only 62% of patients in TD and 50% of patients in PIGD subtypes remained stable. The mean levodopa equivalent daily dose (LEDD) was higher in the PIGD subtype (276.92 ± 232.91 mg; p = 0.01). Lower LEDD [p < 0.05, odds ratio (OR) 0.99, 95% confidence interval (CI): 0.98–0.99] and higher TD/PIGD ratios (p < 0.05, OR 1.77, 95% CI: 1.29–2.43) were independent predictors of stability of TD subtype with an area under the curve (AUC) of 0.787 (95%CI: 0.669–0.876), sensitivity = 57.8%, and specificity = 89.7%.Conclusion: Only 50–62% of PD motor subtypes as defined by MDS-UPDRS remained stable over 3 years. TD/PIGD ratio and baseline LEDD were independent predictors for TD subtype stability over 3 years.

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