Validation of the Danish versions of the Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaires...

Objective: This study aimed to validate the Danish versions of the Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaire (BRAF-MDQ) and BRAF Numerical Rating Scale version 2 (NRSv2).Method: We tested face and content validity, internal consistency, criterion validity, construct validity, and reproducibility for the BRAF-MDQ, and face and criterion validity and reproducibility for the BRAF-NRS.Results: In all, 224/236 patients (95%) completed the questionnaires [70% female, mean ± sd age 59 ± 13.04 years, disease duration 11.2 ± 9.49 years, Health Assessment Questionnaire (HAQ) 0.724 ± 0.70, and 28-joint Disease Activity Score-C-reactive protein 2.55 ± 1.24]. The unidimensionality for the physical and cognitive fatigue subscales was confirmed, whereas the living with fatigue and emotional fatigue subscales were not unidimensional. Cronbach's α was 0.94 for the BRAF-MDQ total and 0.78-0.92 for the four subscales. The correlations between BRAF-MDQ and various measures were: 36-item Short Form Health Survey (SF-36) vitality subscale, 0.75; Hospital Anxiety and Depression Scale (HADS) anxiety subscale, 0.65; HADS depression subscale, 0.62; visual analogue scale (VAS) pain, 0.62; VAS global, 0.73; and HAQ, 0.62. The intraclass correlation coefficient for agreement was 0.995. A Bland-Altman plot showed a mean ± sd difference of -1.9 ± 3.62 for BRAF-MDQ. Correlation coefficients between the BRAF-NRSv2 subscales and other subscales were: BRAF-MDQ subscales, 0.57-0.93; SF-36 vitality subscale, 0.54-0.68; and VAS fatigue, 0.66-0.82.Conclusions: The Danish BRAFs are considered valid and reliable for use among Danish patients with rheumatoid arthritis, despite the subscales living with fatigue and emotional fatigue not being unidimensional, as they are in the original version.