title: Rasch measurement in the assessment of amytrophic lateral sclerosis patients.
abstract: This paper examines the sensitivity to change over time of the Amyotrophic Lateral Sclerosis Assessment Questionnaire (ALSAQ-40). Individuals' health status change was assessed by means of the Rasch-based Reliable Change Index (RCI) for ALSAQ-40 questionnaires completed on two occasions, three months apart. In addition, at follow-up respondents indicated how much change they had experienced since baseline via dimension-specific self reported transition questions. 764 individuals returned questionnaires at baseline and follow-up. For all dimensions, of respondents defined by the RCI as worse, a majority rated themselves as worse. However, on two dimensions over 60% of the respondents who rated themselves as being worse were defined as unchanged by the RCI. As with effect size smaller RCI cut-off points might be needed for subjects with ALS. This study confirms that the ALSAQ-40 is a valid and responsive disease specific health related quality of life instrument for use in studies of patients with ALS or other motor neuron diseases.
authors.affiliation: Department of Public Health, Institute of Health Sciences, University of Oxford, Old Road, Headington, Oxford OX3 7LF, UK. josephine.norquist@dphpc.ox.ac.uk
authors.forename: Josephine M
authors.initials: JM
authors.lastname: Norquist
authors.forename: Ray
authors.initials: R
authors.lastname: Fitzpatrick
authors.forename: Crispin
authors.initials: C
authors.lastname: Jenkinson
mesh_terms: D000203:Activities of Daily Living; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology* / Q000523:psychology; D004739:England; D006801:Humans; D015233:Models, Statistical; D012647:Self-Assessment; D012680:Sensitivity and Specificity; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires; D013995:Time