Factors associated with discrepancies in disease activity as assessed by SDAI and RAPID3 in patients with rheumatoid arthritis: Data from a multicentre observational study (T-FLAG)

Objectives: The present study aimed to examine discrepancies between assessments based on Routine Assessment of Patient Index Data 3 (RAPID3) and Simple Disease Activity Index (SDAI) in rheumatoid arthritis (RA) patients with controlled disease activity.

Methods: Data from 464 RA patients in SDAI remission or low disease activity (REM/LDA) were analysed. Patient-reported outcome (PRO) measures, including Health Assessment Questionnaire Disability Index (HAQ-DI), 25-question Geriatric Locomotive Function Scale (GLFS-25), and Kihon checklist (KCL), were assessed. Logistic regression models were used to identify factors associated with RAPID3 moderate or high disease activity (MDA/HDA). Cutoff values of RAPID3 MDA/HDA for each PRO evaluation item were determined using receiver operating characteristic curve analysis.

Results: Among RA patients in SDAI REM/LDA, 84.9% were in RAPID3 REM/LDA. Multivariable analysis revealed that HAQ-DI, GLFS-25, and KCL were independently associated with RAPID3 MDA/HDA. Subdomain analysis of KCL revealed that activities of daily living, physical function, cognitive function, and depressive mood were significantly associated with RAPID3 MDA/HDA. Cutoff values for HAQ-DI and KCL were 0.38 and 8, respectively.

Conclusions: In RA patients with controlled disease activity, discrepancies between RAPID3 and SDAI assessments were observed, with factors such as HAQ-DI, GLFS-25, and KCL being independently associated with RAPID3 MDA/HDA.