Expert evaluations of fatigue questionnaires used in rheumatoid arthritis: a Delphi study among patients, nurses and rheumatologists in the Netherlands.

OBJECTIVES: Evaluating fatigue items from traditional questionnaires and a new scale (BRAF-MDQ) by experts in rheumatoid arthritis (RA). This evaluation was part of a study to select fatigue items to develop an item bank for a Dutch computer-adaptive test (CAT) for RA. Experts' opinions were incorporated since they are essential for content validity of measurement instruments.
METHODS: The 60 items of the SF-36 subscale vitality, FACIT-F, POMS subscale fatigue/inertia, MAF and the recently developed BRAF-MDQ were evaluated by rheumatologists, nurses and RA patients in a Delphi procedure. Items were selected for development of the item bank/CAT if rated as adequate by at least 80% of the participants (when 50% or less they were excluded). On the basis of participants' comments, remaining items were re-worded and re-evaluated in the following round. The procedure stopped when all items were selected or rejected.
RESULTS: Ten rheumatologists, 20 nurses and 15 RA patients participated. After the first round, 40% of the traditional items and 60% of the BRAF-MDQ items were directly selected and 3 items of the traditional questionnaires and 1 item of the BRAF-MDQ were directly excluded. Remaining items were re-worded, eight of which were presented for re-evaluation in the second round. Finally, 90% of the items from the traditional questionnaires and 95% of the items from the new BRAF-MDQ were included in our item pool.
CONCLUSIONS: Fifty-five of the 60 items (92%) from fatigue questionnaires proved to have good content validity and were feasible for use in the Netherlands, some after adaptation.