Background Chronic nasal carriage of Staphylococcus aureus (SA) has been shown to increase the risk of relapse in patients with Granulomatosis with polyangiitis (GPA). B cell depletion with Rituximab (RTX) is effective in inducing and maintaining remission in GPA. However B cell depletion and hypogammaglobulinemia during RTX could increase the risk of chronic SA nasal carriage.
Objectives To investigate the effect of long-term RTX treatment on chronic SA nasal carriage, the risk of relapses, severe infections and hypogammaglobulinemia in GPA patients.
Methods Cohort study with prospectively collected nasal swab data in 29 GPA patients on RTX (median RTX dose of 9 g) treatment for a median period of 49 months. Patients (52% men, median age 50 (19-75) at RTX initiation, 86% PR3-ANCA positive, 3% MPO-ANCA positive and 10% ANCA negative, 66% and 59% with respectively pulmonary and renal involvement) had received a cumulative dose of cyclophosphamide of 17 (0-250) g.
Nasal swabs were collected prior and during RTX for a median of 3 and 9 swabs respectively. Persistent SA nasal carriage was defined as the presence of SA in more than 75% of nasal swabs.
Results The frequency of persistent SA nasal carriage did not change before (20%) and after RTX (28%) (p=0.562). Persistent SA nasal carriage did not increase the risk of relapses (p=0.646), severe infections (p=0.357) or hypogammaglobulinemia (p=1.00), but reduced the risk of chronic infections (p=0.033) during RTX.
Patients without nasal SA carriage during RTX maintenance were at increased risk to discontinue RTX due to hypogammaglobulinemia (p=0.048). They had less lung involvement (p=0.032), more disease activity at baseline (p=0.010), lower CD4 cell count after RTX 2 g (p=0.023) and larger decline of total Ig after RTX 2g (p=0.045) and at last visit (p=0.021).
Conclusions Long-term RTX maintenance therapy in GPA patients did not influence SA nasal carriage status. Persistent SA carriage during long-term RTX treatment did not increase the risk of relapses and infections and was associated with a lower risk of developing hypogammaglobulinemia. Our results suggest that long-term RTX treatment is better tolerated in GPA patients with chronic SA nasal carriage.
Disclosure of Interest None declared
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