Belgian rheumatologists' preferences regarding measures of disease activity in patients with rheumatoid arthritis: results from a mixed-methods study

The reliability and clinical usefulness of the different composite disease activity scores and their individual components in Rheumatoid Arthritis (RA) are still debated. This study investigated which measures of disease activity were preferred by rheumatologists. A mixed-method study was performed. First, ten Belgian rheumatologists were invited for individual interviews on their current practice and preferences for measurement of RA disease activity. Results of this qualitative study and evidence from literature served as input for developing a survey. This survey asked rheumatologists to rate preferred standard disease activity score(s), their individual components, ultrasound and related patient-reported outcomes (PROs), by maximum difference scaling. The relative importance score (RIS) for each indicator was calculated using hierarchical Bayes modeling. The qualitative study included 6/10 invited rheumatologists. Composite scores and components were perceived as useful, while PROs were found subjective. Interestingly, ultrasound was used to mediate discrepancies between physician and patient. The survey based on this was sent to 244 Belgian rheumatologists, 83/244 (34%) responded, including 66/83 (80%) complete and 17/83 (20%) incomplete surveys (two missing essential information). Most rheumatologists (75/81, 93%) used a disease activity score and 68/81 (84%) preferred the DAS28-CRP. Swollen joint count obtained the highest mean ± SD RIS (22.54 ± 2.64), followed by DAS28 ESR/CRP (20.61 ± 4.06), ultrasound (16.47 ± 7.97), CRP (13.34 ± 6.11) and physician's global assessment (12.59 ± 7.83). PROs including fatigue, pain, and patient's global assessment, and Health Assessment Questionnaire, obtained the lowest mean RIS (0.34-2.54). Rheumatologists place more faith in self-assessed disease activity components or in laboratory tests. Trust in PROs to evaluate disease activity is low in clinical practice.