Use of mucosal eosinophil count as a guide in the management of chronic rhinosinusitis

Background: Chronic rhinosinusitis (CRS) is a local inflammatory process driven by eosinophils. Mucosal eosinophil count (MEC) has previously been demonstrated to be a reliable indicator of disease severity. We aim to evaluate use of MEC in guiding medical management of CRS after functional endoscopic sinus surgery (FESS). Methods: We retrospectively reviewed patients with CRS who underwent FESS from 2004 to 2017. Tissue MEC per high-power field (HPF) was determined by pathologic examination. MECs were compared by polyp status, postoperative medication requirements, and revision surgery. Patients received normal saline (NS) nasal irrigations with additional treatment as needed for disease control: 1-drug therapy (1-DT) intranasal steroid spray (ISS), 2-drug therapy (2-DT) ISS plus budesonide nasal irrigations (BNI) or leukotriene receptor antagonist (LRA), or 3-drug therapy (3-DT) ISS plus BNI and LRA. Correlations between MEC and 22-item Sino-Nasal Outcome Test (SNOT-22), preoperative computed tomography (CT), and nasal endoscopy scores were evaluated. Results: A total of 156 patients were included. Fifty-seven were managed with 1-DT, 35 with 2-DT, and 62 with 3-DT. Across all patients, mean postoperative 6-month and 1-year SNOT-22 (18.1 ± 17.0, 18.1 ± 20.2, respectively) and nasal endoscopy (3.6 ± 3.8, 3.6 ± 4.1, respectively) scores were significantly lower than preoperative scores (37.4 ± 22.8, 6.5 ± 4, respectively). With increasing MEC, odds of requiring 2-DT (odds ratio [OR] = 1.1, p = 0.0002), 3-DT (OR = 1.12, p < 0.0001), and revision surgery (OR = 1.11, p < 0.0001) were significantly increased. Preoperative endoscopy (ρ = 0.44, p < 0.0001) and CT scores (ρ = 0.51, p < 0.0001) and postoperative 6-month (ρ = 0.55, p < 0.0001) and 1-year (ρ = 0.4, p < 0.0001) endoscopy scores demonstrated good correlation with MEC. Conclusion: MEC correlates with objective clinical disease severity and may guide aggressiveness of management for the individual patient.