Minimal clinically important differences for the experiences of daily living parts of movement disorder society-sponsored unified Parkinson's disease rating scale

Background: The minimal clinically important difference is the smallest change of scores clinically meaningful to patients.

Objectives: We aimed to calculate these threshold values in association with the International Parkinson and Movement Disorder Society UPDRS (MDS-UPDRS) Parts I and II and to evaluate the feasibility of the composite score of Part I and II (MDS-UPDRS I+II) as an outcome.

Methods: Nine hundred eighty-five paired investigations of 365 patients were reviewed, implementing three different techniques simultaneously.

Results: Based on the ordinal regression modeling, the MDS-UPDRS I+II score is an applicable outcome measure. Any improvement greater than 2.64 points or any worsening more than 2.45 points on MDS-UPDRS Part I represent a minimal, yet clinically meaningful change. In reference to Part II, the smallest changes considered clinically relevant were 3.05 and 2.51 points for improvement and deterioration, respectively. The thresholds for MDS-UPDRS I+II were 5.73 points for improvement and 4.70 points for worsening.

Conclusions: Our minimal clinically important difference thresholds can be utilized in clinical practice in judging clinical relevance. © 2016 International Parkinson and Movement Disorder Society.