The Gilles de la Tourette syndrome-quality of life scale (GTS-QOL): development and validation

• Published in: Neurology Vol. 71; no. 18; p. 1410
• Main Authors: Cavanna, A E, Schrag, A, Morley, D, Orth, M, Robertson, M M, Joyce, E, Critchley, H D, Selai, C
• Format: Journal Article
• Language: English
• Published: United States 28.10.2008
• Subjects: Adult; Factor Analysis, Statistical; Female; Humans; Male; Middle Aged; Principal Component Analysis; Psychometrics - methods; Quality of Life; Reproducibility of Results; Severity of Illness Index; Surveys and Questionnaires - standards; Tourette Syndrome - physiopathology; Tourette Syndrome - psychology
• ISSN: 1526-632X
• DOI: 10.1212/01.wnl.0000327890.02893.61

Gilles de la Tourette syndrome (GTS) is a chronic neuropsychiatric disorder which has a significant detrimental impact on the health-related quality of life (HR-QOL) of patients. However, no patient-reported HR-QOL measures have been developed for this population. The development and validation of a new scale for the quantitative assessment of HR-QOL in patients with GTS. In stage 1 (item generation), a pool of 40 potential scale items was generated based on interviews with 133 GTS outpatients, literature review, and consultation with experts. In stage 2 (scale development), these items were administered to a sample of 192 GTS outpatients. Standard statistical methods were used to develop a rating scale satisfying criteria for acceptability, reliability, and validity. In stage 3 (scale evaluation), the psychometric properties of the resulting scale were tested in a second sample of 136 subjects recruited through the UK-Tourette Syndrome Association. Response data analysis and item reduction methods led to a final 27-item GTS-specific HR-QOL scale (GTS-QOL) with four subscales (psychological, physical, obsessional, and cognitive). The GTS-QOL demonstrated satisfactory scaling assumptions and acceptability; both internal consistency reliability and test-retest reliability were high (Cronbach alpha > or =0.8 and intraclass correlation coefficient > or =0.8); validity was supported by interscale correlations (range 0.5-0.7), confirmatory factor analysis, and correlation patterns with other rating scales and clinical variables. The Gilles de la Tourette syndrome (GTS)-specific health-related quality of life (HR-QOL) scale (GTS-QOL) is proposed as a new disease-specific patient-reported scale for the measurement of HR-QOL in patients with GTS, taking into account the complexity of the clinical picture of GTS.