Objective: To identify the items in Part III of the MDS-UPDRS scale that are predictive to Part II items in early PD patients.

Background: It is well known that MDS-UPDRS part II and part III total scores are significantly correlated with each other. However, neither individual item-level correlations have nor the ability of items in Part III to predict part II of MDS-UPDRS have been reported. PPMI is an ongoing observational study that enrolled 423 treatment-naïve PD subjects at entry. MDS-UPDRS is measured at Baseline and every 3 months in the first year and every 6 months afterwards.

Method: Data were download from the PPMI in June 2017. Month 24 MDS-UPDRS data were analyzed using a multivariate regression model with each MDS-UPDRS part II item score as the response, and all the MDS-UPDRS part III item scores and baseline demographics (age, gender, PD type of TD/PIGD, years since disease onset) as predictors. Backward selection and LASSO methods were used to identify the part III items that are statistically important predictive to each part II item.

Results: Data from the 342 of the 423 PD patients in the study who had MDS-UPDRS scores at Month 24 were used in the analyses. The most frequently selected predictors from Part III items are: 3.1 Speech; 3.3 b/c/d/e Rigidity; 3.9 Arising from chair; 3.13 Posture; 3.14 Global spontaneity of movement. Dressing, Walking and Getting out of Bed were among the Part II ADL associated with the most predictors from Part III. Analyses results from the LASSO method, or using baseline data, are generally consistent with the backward selection method results.

Conclusion: Different sets of items in Part III of MDS-UPDRS were found to be predictive to different part II item. Walking and Getting out of bed may be great candidates for overall measures of ADL as they are significantly affected by multiple underlying symptoms such as rigidity, posture instability and tremor items in Part III.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/mds-updrs-part-iii-predictors-of-part-ii-item-scores-in-ppmi/