Enfeeblement in Essential Tremor: Development and Validation of a New Psychometric Measure.

Introduction: Despite a growing body of knowledge regarding essential tremor (ET), past studies have fallen short in capturing the full impact of ET on patients and caregivers. We propose enfeeblement (i.e., having the qualities of being prematurely old, helpless, or debilitated) as a novel clinical outcome measure in ET. Due to the lack of enfeeblement scales for ET in the literature, we developed and validated an enfeeblement scale for ET. Methods: The Essential Tremor Enfeeblement Survey (ETES) consists of eight 5-point Likert-type scale questions and is designed to be a caregiver-reported outcome. Results: Enfeeblement scores showed a floor effect of 15.3%, no ceiling effects, and demonstrated good overall test-retest reliability (intraclass correlation coefficient = 0.73), favorable internal consistency (Cronbach alpha coefficient = 0.92) and good convergent validity. Conclusion: The ETES has robust properties. Aside from future studies of enfeeblement in ET, enfeeblement should be explored more broadly as a psychometric measure across other neurological disorders.