Rheumatoid arthritis patients initiating rituximab with low number of previous bDMARDs failures may effectively reduce rituximab dose and experience fewer serious adverse events than patients on full dose: a 5-year cohort study

BACKGROUND: Rituximab is used for the treatment of active rheumatoid arthritis. In the present study, we examined the long-term flare risk and safety of reduced doses of rituximab. PATIENTS-METHODS: This was a prospective, observational, single-center study of patients starting rituximab on standard dose (SD). Patients were switched to low dose (LD) (1 g every 6 months), based on the treating rheumatologist’s decision after having achieved sustained clinical responses, while the rest of the patients continued on standard dose (SD). During a 60-month period, we assessed (Kaplan–Meier survival analysis) the relapse rate (increase ≥ 1.2 in DAS28-ESR for ≥ 6 months) and discontinuations due to treatment failure in the low dose group, and we compared the incidence of serious adverse events (SAEs) between LD and SD groups. RESULTS: Out of 361 patients [females 83.4%, mean age 61.9 (10.6) years, seropositive 50.3%, median total comorbidities count 4], 81 patients (22.4%) entered LD in a median time of 24 months (95% CI 18–30 months). Seropositivity (OR 1.823), more than 2 previous bDMARDs failures (OR 0.428), and DAS28 < 4.88 at 6 months (OR 2.329) predicted the odds of entering LD (p < 0.05 for all). During 60 months of follow-up, only 7.5% of patients on LD relapsed. Patients on LD had significantly less SAEs and all-cause hospitalizations as compared to the SD group (p < 0.05 for all). Linear regression analysis showed that previous hospitalization while on bDMARDs (p < 0.0001), use of prednisolone > 5 mg/day while on rituximab (p < 0.0001), and a history of ≥ 2 previous csDMARDs (p = 0.041) predicted the risk of SAEs. CONCLUSION: In a cohort of patients with established RA and significant comorbidities who taper rituximab after substantial initial disease activity improvement, a low rate of relapses and lower risk of SAEs compared to SD were recorded. Seropositivity, a lower number of previous bDMARDs use, and lower DAS28 at 6 months predicted the probability of entering the LD regimen. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13075-022-02826-6.