Rheumatoid arthritis patients on persistent moderate disease activity on biologics have adverse 5-year outcome compared to persistent low-remission status and represent a heterogeneous group

Background The long-term outcome of rheumatoid arthritis (RA) patients who in clinical practice exhibit persistent moderate disease activity (pMDA) despite treatment with biologics has not been adequately studied. Herein, we analyzed the 5-year outcome of the pMDA group and assessed for within-group heterogeneity. Methods We included longitudinally monitored RA patients from the Hellenic Registry of Biologic Therapies with persistent (cumulative time ≥ 50% of a 5-year period) moderate (pMDA, 3.2 < DAS28 ≤ 5.1) or remission/low (pRLDA, DAS28 ≤ 3.2) disease activity. The former was further classified into persistent lower-moderate (plMDA, DAS28 < 4.2) and higher-moderate (phMDA, DAS28 ≥ 4.2) subgroups. Five-year trajectories of functionality (HAQ) were the primary outcome in comparing pRLDA versus pMDA and assessing heterogeneity within the pMDA subgroups through multivariable mixed-effect regression. We further compared serious adverse events (SAEs) occurrence between the two groups. Results We identified 295 patients with pMDA and 90 patients with pRLDA, the former group comprising of plMDA ( n = 133, 45%) and phMDA ( n = 162, 55%). pMDA was associated with worse 5-year functionality trajectory than pRLDA (+ 0.27 HAQ units, CI 95% + 0.22 to + 0.33; p < 0.0001), while the phMDA subgroup had worse 5-year functionality than plMDA (+ 0.26 HAQ units, CI 95% 0.18 to 0.36; p < 0.0001). Importantly, higher persistent disease activity was associated with more SAEs [pRLDA: 0.2 ± 0.48 vs pMDA: 0.5 ± 0.96, p = 0.006; plMDA: 0.32 ± 0.6 vs phMDA: 0.64 ± 1.16, p = 0.038]. Male gender ( p = 0.017), lower baseline DAS28 ( p < 0.001), HAQ improvement > 0.22 ( p = 0.029), and lower average DAS28 during the first trimester since treatment initiation ( p = 0.001) independently predicted grouping into pRLDA. Conclusions In clinical practice, RA patients with pMDA while on bDMARDs have adverse long-term outcomes compared to lower disease activity status, while heterogeneity exists within the pMDA group in terms of 5-year functionality and SAEs. Targeted studies to better characterize pMDA subgroups are needed, in order to assist clinicians in tailoring treatments.