Psychometric testing of a german version of the evaluation of daily activity questionnaire in rheumatoid arthritis

Background: The Evaluation of Daily Activity Questionnaire (EDAQ) is a patient reported outcome (PRO) of activity limitations. The English EDAQ is reliable, valid and a comprehensive measure of the commonest problems experienced by people with rheumatoid arthritis (RA) and musculoskeletal conditions [1,2]. It includes 138 items in 14 ‘domains’ (Eating/ Drinking; Personal Care; Dressing; Bathing; Cooking; Moving Indoors; House Cleaning; Laundry; Moving and Transfers; Moving Outdoors; Gardening/Household Maintenance; Caring; Leisure/ Social Activities). All items are scored on a 0-3 scale (no difficulty to unable to do). There is no similar measure available in German. PROs must be tested in target languages and conditions, prior to use, to ensure validity and reliability. Objectives: To linguistically validate a German EDAQ and test it’s reliability and validity in German-speaking people with RA. Methods: The English EDAQ was forward-backward translated to German. Cognitive debriefing interviews were conducted and the German EDAQ developed. Participants from a Rheumatology clinic (Switzerland) and arthritis patient organizations (Switzerland, Germany, Austria) then completed postal questionnaires including: demographic questions, German EDAQ, Health Assessment Questionnaire (HAQ), SF36v2, RA Quality of Life scale (RAQOL), and a hand pain numeric rating scale (NRS). Three weeks later, the EDAQ was mailed again. Test-retest reliability of domain scores, and validity of the 14 German EDAQ domains against the other measures, were evaluated using nonparametric correlations. Internal consistency was tested using Cronbach’s alpha. Results: Six German-speaking people with RA were interviewed, recommended changes reviewed by the expert panel and the German EDAQ agreed. 163 people then completed questionnaires: 145 women and 18 men; mean age = 52.84 (SD14.94) years; mean RA duration = 15.73 years (SD12.12). 85(45%) were employed; 21 had children <18y at home. Median pain score = 4 (IQR 2-6) and fatigue = 5 (IQR 3-7).107 (65%) completed a second questionnaire. Test-retest reliability of total domain scores was excellent for all domains (rs= 0.80 - 0.93). Internal consistency was high in all domains: Cronbach’s alpha= 0.84 – 0.96. All EDAQ domains (except Caring) correlated significantly (p<0.001) with: HAQ rs= 0.73- 0.87; SF36v2 (Physical Function) rs= -0.61 to -0.84; SF36v2 Bodily Pain rs=-0.53 to -0.65; SF36v2 (Vitality) rs= -0.27 to-0.31; RAQOL rs= 0.55-0.68; and hand pain rs=0.43-0.52. Correlations were lower in the ‘Caring’ domain due to the smaller sample size (n=77), although mostly still significant (p<0.01; rs=0.25 to 0.42; except Sf36v2 Vitality = -0.10 non- significant). Conclusions: The German EDAQ is a valid and reliable measure of daily activity in people with RA. Either the whole EDAQ or individual domains can be used in clinical practice to identify clients’ daily activity problems and help find solutions, or as an outcome measure in research and audit. A User Manual is available [3]. References: [1] Hammond et al (2015) Rheumatology 54:1605-1615; [2] Hammond et al (2017) Disabil Rehabil DOI: 10.1080/09638288.2017.1323027 [3] Hammond A et al. The EDAQ User Manual v2. 2016: https://usir.salford.ac.uk/30752/