Minimal clinically important difference on the Motor Examination part of MDS-UPDRS

Abstract

Background: Recent studies increasingly utilize the Movement Disorders Society Sponsored Unified Parkinson's Disease Rating Scale (MDS-UPDRS). However, the minimal clinically important difference (MCID) has not been fully established for MDS-UPDRS yet.

Objective: To assess the MCID thresholds for MDS-UPDRS Motor Examination (Part III).

Methods: 728 paired investigations of 260 patients were included. At each visit both MDS-UPDRS and Clinician-reported Global Impression-Improvement (CGI-I) scales were assessed. MDS-UPDRS Motor Examination (ME) score changes associated with CGI-I score 4 (no change) were compared with MDS-UPDRS ME score changes associated with CGI-I score 3 (minimal improvement) and CGI-I score 5 (minimal worsening). Both anchor- and distribution-based techniques were utilized to determine the magnitude of MCID.

Results: The MCID estimates for MDS-UPDRS ME were asymmetric: -3.25 points for detecting minimal, but clinically pertinent, improvement and 4.63 points for observing minimal, but clinically pertinent, worsening.

Conclusions: MCID is the smallest change of scores that are clinically meaningful to patients. These MCID estimates may allow the judgement of a numeric change in MDS-UPDRS ME on its clinical importance.

Keywords: Clinician reported outcome; Minimal clinically important change; Minimal clinically important difference; Receiver operating characteristic curve; UPDRS.