Characterization of Chronic Rhinosinusitis Patients Based on Markers of Type 2 Inflammation: Findings From the European CRS Outcome Registry (CHRINOSOR)

Primary chronic rhinosinusitis (CRS) can be classified based on the sinuses involved and the dominant endotype of the mucosal inflammation. Since the introduction of type 2 targeted biologics as treatment option for CRS, assessment of the inflammatory status has gained importance in CRS patients. We here aimed to characterize CRS patients with and without elevated markers of type 2 inflammation. CRS patients who visited the outpatient ENT clinic in one of the 10 tertiary centers in 7 European countries were invited to use the Galenus Health mobile application for the monitoring of their disease. CRS patients (n = 281) were stratified according to blood eosinophil counts or BEC (< 150 cells/μL: 21.6% of patients, ≥ 150 cells/μL: 78.4%; < 250 cells/μL: 36.3%, ≥ 250 cells/μL: 63.7%) and serum total IgE (< 100 IU/mL: 59.9%, ≥ 100 IU/mL: 40.1%). BEC and serum total IgE did not correlate well (Spearman r = 0.06; p = 0.39). CRS patients with BEC ≥ 150 cell/μL or ≥ 250 cells/μL, respectively, showed increased NPS, SNOT-22, VAS for total CRS symptoms, loss of smell, nasal blockage, runny nose compared to patients with BEC below 150 or 250 cells/μL. CRS patients with increased serum total IgE (≥ 100 IU/mL) did not show differences in the outcome parameters compared to patients with levels below 100 IU/mL. CRS patients with asthma (58.9%) showed increased SNOT-22 and VAS loss of smell compared to patients without asthma. A significant proportion of CRS patients exhibit a type 2 endotype, characterized by blood eosinophilia (78%), increased serum total IgE (40%) and/or concomitant asthma (59%). Our results underline the usefulness of eosinophils as a marker of type 2 inflammation and severity but challenge the utility of serum total IgE since it does not correlate with any of the markers of severity.