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