Translation and Validation of the Quality of Life in Essential Tremor Rating Scale

Background Essential tremor is a common movement disorder, characterized by kinetic tremor, most commonly of the upper extremities. The Quality of Life in Essential Tremor (QUEST) scale is an oft‐used subjective rating scale of tremor severity and quality of life (QoL) in these patients, including for monitoring subjective improvement after advanced treatment. It contains subdomains concerned with overall and health‐related QoL, a self‐assessment of tremor severity and of the functional impact of tremor on activities of daily living. The questionnaire has not been validated in Danish. This study was aimed at translating and validating the QUEST and piloting it among Danish ET patients. Methods The translation and cultural adaptation of the QUEST was carried out per the guidelines of the World Health Organization (WHO) and the International Society of Pharmacoeconomics and Outcomes Research (ISPOR) task force for translation and cultural adaptation. It was subsequently disseminated among a cohort of ET patients. Results The QUEST was successfully translated and piloted among 112 ET patients. Respondents found the QUEST to be understandable (75/77; 97.4%). For categorical items, there was a high degree of agreement in responses at retest (60.0%–94.0%). According to Cohen′s kappa, agreement was mostly strong. Continuous outcomes were more variable, particularly the subdomains of the functional self‐assessment. The mean score for each subdomain ranged from 19.46 (SD 21.87) for work and finance, 24.13 (SD 25.31) for communication, 32.49 (SD 23.21) for psychosocial, 40.21 (SD 34.11) for hobby and leisure, and 42.77 (SD 27.08) for physical. In general, subdomains were weakly to moderately correlated with overall health and QoL. Conclusion We have successfully translated and validated the QUEST questionnaire for use among Danish ET patients. The questionnaire is now available for Danish clinicians and researchers treating ET patients. The results indicate some unmet needs in the Danish cohort of tremor patients.