Dose reduction of rituximab in clinical practice: a retrospective cohort study of rheumatoid arthritis patients in low disease activity on rituximab.

Abstract

Objectives: To determine the effects of dose reduction of rituximab (RTX) on rheumatoid arthritis (RA) disease activity in clinical practice.

Methods: Retrospective cohort study of RA patients using RTX, in stable low disease activity (i.e. Disease Activity Score 28-joint count CRP (DAS28-CRP) ≤3.5 for ≥6 consecutive months) and ≥2 DAS28-CRP measurements. We identified three treatment periods: 1) full dose RTX, 2) RTX dose reduction, and 3) stable RTX dose (and interval) after tapering. Linear mixed-model analysis was used to estimate mean DAS28-CRP during these periods. Rituximab use was assessed as the median percentage of the RTX Daily Defined Dose (%DDD) per period, with 1 x 1000 mg/6 months as reference.

Results: 387 patients were included in the cohort with a median of 8 DAS28-CRP measurements (Q1-Q3:4-13) available per patient and median follow-up time of 44 months (Q1-Q3: 23-76). 299 patients tapered RTX and entered period 2 at least once, of whom 226 also entered period 3. Mean DAS28-CRP were 2.37 (95% CI: 2.29, 2.44) for period 1, 2.33 (95% CI: 2.25, 2.40) for period 2, and 2.27 (95% CI: 2.18, 2.35) for period 3, the latter significantly lower compared to period 1 (p=0.025). %DDD for the three time periods were 96%, 57% and 49%, respectively.

Conclusions: Dose reduction of RTX in clinical practice is effective for many RA patients and leads to relevant dose reduction. Together with other previously proven benefits of ultra-low dose RTX, wider implementation of ultra-low dose RTX in RA patients should be considered.