The reliability and validity of the English version of the Evaluation of Daily Activity Questionnaire for people with rheumatoid arthritis.

OBJECTIVES: The Evaluation of Daily Activity Questionnaire (EDAQ) includes 138 items in 14 domains identified as important by people with RA. The aim of this study was to test the validity and reliability of the English EDAQ. METHODS: A total of 502 participants completed two questionnaires 3 weeks apart. The first consisted of the EDAQ, HAQ, RA Quality of Life (RAQoL) and the Medical Outcomes Scale (MOS) 36-item Short-Form Health Survey (SF-36v2), and the second consisted of the EDAQ only. The 14 EDAQ domains were tested for: unidimensionality-using confirmatory factor analysis; fit, response dependency, invariance across groups (differential item functioning)-using Rasch analysis; internal consistency [Person Separation Index (PSI)]; concurrent validity-by correlations with the HAQ, SF-36v2 and RAQoL; and test-retest reliability (Spearman's correlations). RESULTS: Confirmatory factor analysis of the 14 EDAQ domains indicated unidimensionality, after adjustment for local dependency in each domain. All domains achieved a root mean square error of approximation <0.10 and satisfied Rasch model expectations for local dependency. DIF by age, gender and employment status was largely absent. The PSI was consistent with individual use (PSI = 0.94 for all 14 domains). For all domains, except Caring, concurrent validity was good: HAQ (rs = 0.72-0.91), RAQoL (rs = 0.67-0.82) and SF36v2 Physical Function scale (rs = -0.60 to -0.84) and test-retest reliability was good (rs = 0.70-0.89). CONCLUSION: Analysis supported a 14-domain, two-component structure (Self care and Mobility) of the EDAQ, where each domain, and both components, satisfied Rasch model requirements, and have robust reliability and validity.

Linguistic validation and cultural adaptation of an English version of the evaluation of daily activity questionnaire in rheumatoid arthritis.

BACKGROUND: To linguistically validate and culturally adapt the Evaluation of Daily Activity Questionnaire (EDAQ) for use in rheumatoid arthritis (RA) from Swedish to British English. The EDAQ is a patient reported outcome measure of daily activity ability. It includes 11 activity domains (Eating and Drinking; Personal Care; Dressing; Bathing; Cooking; Moving Indoors; House Cleaning; Laundry; Moving and Transfers; Communication; Moving Outdoors) and was developed for use in rheumatoid arthritis (RA). METHODS: The EDAQ was translated from Swedish to English using standard methods. Activity diaries, cognitive debriefing interviews and focus groups were completed with people with RA to: generate new culturally applicable items; identify important items in the Swedish version to retain in the English version; and develop the English EDAQ based on their views of content and layout. Content validity was established by linking the EDAQ to the International Classification of Functioning RA Core Set. RESULTS: The English EDAQ translation was harmonized with the Swedish version to ensure equivalence of meaning. Sixty-one people with RA participated. 156 activities were identified from 31 activity diaries and included in a draft English EDAQ. Following interviews (n = 20) and four focus groups, 138 activities were retained and three additional domains added (Gardening/Household Maintenance; Caring; and Leisure/Social Activities). Most ICF RA Core Set activities are in the EDAQ. CONCLUSIONS: The English EDAQ is a detailed self-report measure of ability in RA with good content validity.