The reliability, validity and responsiveness of the Restless Legs Syndrome Quality of Life questionnaire (RLSQoL) in a t
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The reliability, validity and responsiveness of the Restless Legs Syndrome Quality of Life questionnaire (RLSQoL) in a trial population Linda Abetz*1, Robert Arbuckle1, Richard P Allen2, Elena Mavraki3 and Jeffrey Kirsch3 Address: 1Mapi Values, Adelphi Mill, Bollington, Macclesfield, SK10 5JB, UK, 2Johns Hopkins Bayview Medical Center, Neurology and Sleep Medicine, Asthma and Allergy Building 1B46b, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA and 3GlaxoSmithKline, Greenford Road, Greenford, Middlesex, UB6 0HE, UK Email: Linda Abetz* - [email protected]; Robert Arbuckle - [email protected]; Richard P Allen - [email protected]; Elena Mavraki - [email protected]; Jeffrey Kirsch - [email protected] * Corresponding author
Published: 05 December 2005 Health and Quality of Life Outcomes 2005, 3:79
doi:10.1186/1477-7525-3-79
Received: 24 June 2005 Accepted: 05 December 2005
This article is available from: http://www.hqlo.com/content/3/1/79 © 2005 Abetz et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract Background: The aim of this study was to determine the reliability, validity and responsiveness of the Restless Legs Syndrome Quality of Life questionnaire (RLSQoL) in a clinical trial setting. Methods: Two matching, placebo-controlled, multinational studies assessing the effectiveness and safety of ropinirole for treating moderate-to-severe Restless Legs Syndrome (RLS) formed the basis of this psychometric assessment. Validity and reliability were assessed using baseline data. Responsiveness was determined using longitudinal data collected at baseline and 12 weeks. Results: A total of 547 subjects formed the baseline validation population; 519 were used for assessing responsiveness (n = 284/263 and 271/248 for both studies, respectively). Construct validity assessment confirmed that an overall life impact score could be calculated. All item-scale correlations were = 0.4, except items 1 (r = 0.36) and 5 (r = 0.35) in one study. Floor and ceiling effects were minimal. Cronbach's alpha values were 0.82 and 0.87, respectively, confirming internal consistency reliability. Correlations with the International Restless Legs Syndrome Study Group's severity rating scale (International Restless Legs Scale; IRLS) were moderate (r = -0.68 and -0.67, respectively; p < 0.0001). The RLSQoL was able to discriminate between levels of sleep problems (p < 0.0001) and between levels of global health status determined by a Clinical Global Impression of severity (CGI-S) (p < 0.0001). Responsiveness was demonstrated by significant differences in overall life impact change scores between CGI improvement levels after 12 weeks (p < 0.0001). Conclusion: The RLSQoL is a valid, reliable and responsive measure of quality of l
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