“…Functional disability was assessed in both samples with a composite score on the Mobility and Self-Care scale of the Impact of Rheumatic Diseases on General Health and Lifestyle (IRGL; Evers, Taal, et al, 1998; Huiskes, Kraaimaat, & Bijlsma, 1990), a questionnaire derived from the Arthritis Impact Measurement Scales (AIMS), which was originally developed to assess various aspects of physical, psychological, and social health in arthritis patients. Previous research showed reliability and validity of the IRGL scales to be highly satisfactory in RA patients (Evers, Taal, et al, 1998; Huiskes et al, 1990), and the instrument from which it was derived, the AIMS, has also been shown to be reliable and valid for use in MS patients (Schiaffino, Shawaryn, & Blum, 1996; Schiaffino et al, 1998). Items of the IRGL scales are scored on a 4- or 5-point Likert scale.…”