Performance of the Rheumatoid Arthritis Impact of Disease (RAID) score in relation to flares in disease activity

Objectives To explore the performance of the EULAR-initiated patient-reported Rheumatoid Arthritis Impact of Disease (RAID) questionnaire in relation to flares in disease activity, including comparison with other disease activity outcomes. Methods Patients with rheumatoid arthritis in sustained remission were randomised to continued stable treatment or tapering in the ARCTIC REWIND project. In patients with flares within 12 months, we compared RAID (total score and components) at the flare visit with the visit prior to and the visit following flare, using Wilcoxon signed-rank test. Similar analyses were performed for patient global assessment, Disease Activity Score (DAS) and C reactive protein (CRP). The discriminative accuracies of RAID, patient global assessment, DAS and CRP with respect to disease activity flares were assessed by receiver operating characteristic (ROC) analyses based on logistic regression models. Flare was defined as a combination of DAS >1.6, a DAS increase >= 0.6 and >= two swollen joints (of 44 examined) or could be recorded if patient and rheumatologist agreed that a clinically significant flare had occurred. Results In total, 248 patients were included in the analyses, with 56 flares. RAID, patient global assessment, DAS and CRP all changed significantly at the visits related to flare (p<0.001). Area under the curve (95% CI) values indicated that RAID (0.88 (0.83 to 0.93)) was significantly more accurate than CRP (0.76 (0.69 to 0.84)) in discriminating flare, and less accurate than patient global assessment (0.92 (0.87 to 0.97)) and DAS (0.94 (0.90 to 0.98)). The RAID components with highest and lowest discriminative accuracies were pain (0.91 (0.86 to 0.95)) and sleep (0.69 (0.59 to 0.79)). Conclusion Disease activity flares were associated with a significant increase in median RAID, supporting its ability to respond to flare.