Most of the Quality of Life in Essential Tremor Questionnaire (QUEST) psychometric properties resulted in satisfactory values

Objective: This study sought to assess the psychometric attributes of the Quality of Life in Essential Tremor Questionnaire (QUEST) by undertaking an independent validation.

Study design and setting: This was an observational, multicenter, cross-sectional study carried out in Neurology Departments of general hospitals. The following assessments were applied: Louis Rating Scale, Clinical Assessment of Tremor, Clinical Global Impression of Severity (CGI-ET), Hospital Anxiety and Depression Scale (HADS), EQ-5D, and QUEST (Spanish version).

Results: One hundred and eighteen consecutive patients were included. According to the CGI-ET, most of patients had mild (42.4%) or moderate (43.2%) impact of tremor on performing daily activities. Fully computable QUEST data were 60.2%. The QUEST Summary Index (QUEST-SI) displayed marginal floor or ceiling effect. On the whole, QUEST internal consistency and reproducibility were satisfactory (Cronbach's alpha values: 0.73-0.86; QUEST-SI intraclass correlation coefficient: 0.77). Factor analysis identified eight factors (73.6% of the variance) that could be grouped into six, relatively coincident with the questionnaire's dimensions. The QUEST-SI correlated moderately with the EQ-5D index (r(S)=-0.40), HADS-Depression (r(S)=0.39), and CGI-ET (r(S)=0.39), and strongly with the QUEST scale for self-evaluation of tremor severity (r(S)=0.63). The standard error of measurement was 8.00.

Conclusion: Apart from a substantial problem of acceptability, most of the tested psychometric attributes of the QUEST resulted satisfactory.