Effect of short-interval rituximab and high-dose corticosteroids on kidney function in systemic sclerosis: Long-term experience of a single centre.

INTRODUCTION: Scleroderma renal crisis (SRC) is a rare but one of the most recognised complications of systemic sclerosis (SSc). Corticosteroid (CS) use has been considered as a major risk factor for SRC. Several studies reported the efficacy of rituximab (RTX) with an acceptable safety profile in SSc. However, data on the long-term effect of high-dose CS concomitant to RTX on kidney function are lacking. METHODS: We retrospectively analysed SSc patients (n = 35) treated with a lower dosage and short-interval RTX and concomitant high-dose CS at the Department of Internal Medicine at the Medical University of Graz between 2010 and 2019. The kidney function was assessed using the estimated glomerular filtration rate (eGFR) at every RTX admission. The annual decline of kidney function was evaluated by linear mixed model analysis. RESULTS: At the RTX initiation, one patient had a decreased kidney function indicated by eGFR < 60 mL/min/1.73 m2 (median: 96 mL/min/1.73 m2 ; interquartile range (IQR): 43-136). Patients received RTX and complementary high-dose CS for a median follow-up time of 3.4 years (range 0.6-9.5). A linear mixed model analysis with the patient as random effect and time from first RTX as fixed effect estimated an annual decline of 1.98 mL/min/1.73 m2 of the eGFR (95% confidence interval: [-2.24, -1.72]; P <.001). During the follow-up period, no patient experienced SRC or a significant drop in kidney function. CONCLUSIONS: A regular, high-dose CS given contemporary to RTX seems to be a safe option for kidney function in patients with SSc. Our findings provide additional knowledge in risk evaluation and planning of individualised therapies or designing clinical studies using RTX.