Modified Unified Wilson's Disease Rating Scale - scale presentation and pilot clinimetric testing

The Unified Wilson's Disease Rating Scale (UWDRS) was first introduced in 2007 to assess neurologic status and impairment in patients with Wilson's disease (WD). However, major issues have been raised, including the lack of assessment of mental and psychiatric status, the lack of instructions for the assessment of certain motor functions, difficulties with gait and posture assessment, and heterogenous response options for questions across the scale.

The development of a modified version of the UWDRS (mUWDRS) was proposed.

A new version of UWDRS with revised wording and options was created, incorporating items from the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS), the Unified Dyskinesia Rating Scale, and the Pantothenate Kinase Associated Neurodegeneration Disease Rating Scale (PKAN-DRS). As in the original, part I of the mUWDRS assesses the level of consciousness. Part II is now divided into two partly self-reported subscales: part IIa assesses 10 daily living activities and a new part IIb addresses cognitive functioning, mental and behavioral status. Part III assesses neurologic status as before, but with modifications for gait and posture items. After 2 rounds of cognitive pretesting, mUWDRS was validated in 7 patients by 8 neurologists for interrater agreement (Fleiss kappa or Kuder Richardson Coefficient) and for internal consistency (Cronbach's alpha).

In the pilot test, interrater agreement with mUWDRS was almost perfect or substantial, with index values of 1 for part I, 0.90 for part IIa, 0.93 for cognitive functioning and 0.86 for behavioral status in part IIb, and 0.826 for part III. A high level of internal consistency was observed, with Cronbach's α of 0.82 for part II and 0.84 for part III.

The mUWDRS, designed to assess both motor and nonmotor symptoms of WD and functional impairment, performed well in pilot testing. Since the modified version of the WD rating scale has a good interrater agreement, a proper validity study is planned to be conducted. The scale is available on: https://www.movementdisorders.org/MDS/MDS-Clinical-Outcome-Assessment.htm.