Wearing-off scales in Parkinson's disease: critique and recommendations

Wearing-off occurs in the majority of patients with Parkinson's disease after a few years of dopaminergic therapy. Because a variety of scales have been used to estimate wearing-off, the Movement Disorder Society commissioned a task force to assess their clinimetric properties. A systematic review was conducted to identify wearing-off scales that have either been validated or used in Parkinson's patients. A scale was designated "Recommended" if it had been used in clinical studies beyond the group that developed it, if it had been specifically used in Parkinson's disease reports, and if clinimetric studies had established that it is valid, reliable, and sensitive. "Suggested" scales met 2 of the above criteria, and those meeting 1 were "Listed." We identified 3 diagnostic and 4 severity rating scales for wearing-off quantification. Two questionnaires met the criteria to be Recommended for diagnostic screening (questionnaires for 19 and 9 items), and 1 was Suggested (questionnaire for 32 items). Only the patient diaries were Recommended to assess wearing-off severity, with the caveat of relatively limited knowledge of validity. Among the other severity assessment tools, the Unified Parkinson Disease Rating Scale version 3 and the version revised from the Movement Disorders Society were classified as Suggested, whereas the Treatment Response Scale was Listed.