The range of Clinical Disease Activity (CDAI) Low Disease Activity (LDA) at baseline is associated with marked differences with time in patients with Rheumatoid Arthritis (RA)

Objective We sought to determine if the range of clinical outcomes across rheumatoid arthritis patients exposed to biologic, or JAK disease‐modifying antirheumatic drugs (b/tsDMARDs) remained consistent with time using the low clinical disease activity index (CDAI;range of 2.8‐10) and remission (CDAI 0‐2.8), along with patient‐reported outcomes (PROs). Methods We used baseline and prospective follow‐up scores from the CorEvitas registry. All patients had measurement of the CDAI and validated PROs at baseline. We examined the evolution of these outcomes to determine if there were meaningful clinical differences with time based on the range of baseline CDAI scores. Results 6,856 patients with RA had baseline CDAI scores that were in CDAI Remission or LDA (0‐10). 19.5% and 19.6% of patients whose baseline CDAI was between 2.8 and 6 (“very low” VLDA) vs. 31.2% and 31.0% of patients with a baseline CDAI >6‐10 (“High LDA; HLDA) exhibited a CDAI >10 at 1 and 2 years respectively (p<0.001for change in CDAI from baseline in the LDA subgroups). In both crude and adjusted models, patients with a CDAI between >6 and 10 were almost twice as likely to have a CDAI in the moderate disease activity range at 1 and 2 years compared with patients in the range of 2.8‐6. Conclusion The definition of CDAI so‐called low disease activity is likely overly broad and includes patients in the upper range of LDA with an inferior prognosis. These differences in outcomes across the range of LDA should be incorporated into therapeutic recommendations that recognize these disparate outcomes.