Incidence of Chronic Rhinosinusitis in Patients Who Receive Rituximab

Rituximab causes B-cell depletion and hypogammaglobulinemia, increasing risk for infections. This study aims to determine the incidence of chronic rhinosinusitis (CRS) in patients following rituximab therapy.

Retrospective cohort study using chart review of patients prescribed rituximab between January 2019 and January 2025.

Multisite study across Mayo Clinic Enterprise locations in Arizona, Florida, Minnesota, and Wisconsin.

Patients with documented rituximab use were included; those with pre-existing CRS were excluded. Demographic and clinical data-including timing and duration of rituximab therapy, CRS diagnosis, comorbidities (asthma, allergic rhinitis, GERD), and need for sinus surgery-were collected. Descriptive statistics summarized patient characteristics. Group comparisons were performed using t-tests, Mann-Whitney U, and chi-square tests. Analyses were conducted using SPSS v28.

Among 17,851 patients prescribed rituximab (median age 64.0 years, M:F ratio 1.1:1), 1105 (6.2%) developed CRS, with an annual incidence of 1.03% (1032 cases per 100,000 person-years). The median duration of rituximab therapy for those diagnosed with CRS was 5.9 months (IQR, 0.5-42.6). Most CRS cases occurred after rituximab discontinuation (62.7%, n = 693) compared to during active treatment (37.3%, n = 412). The median delay between rituximab discontinuation and CRS diagnosis was 17.0 months (IQR, 4.3-41.7).

This study demonstrates an annual incidence of 1.03% for CRS diagnoses following rituximab. While prior studies report varying CRS incidences in the general population (0.25%-0.73%), our findings suggest increased risk among rituximab users. Most CRS diagnoses occurred after rituximab discontinuation, emphasizing the need for a comprehensive medication history review during CRS evaluation.