Eosinophilic and Non-eosinophilic Chronic Rhinosinusitis with Nasal Polyps and Their Clinical Comparison in Indian Population

Eosinophilic chronic rhinosinusitis with nasal polyps (eCRSwNP) and non-eosinophilic chronic rhinosinusitis with nasal polyps (neCRSwNP) are two distinct endotypes of chronic rhinosinusitis with nasal polyps (CRSwNP). The aim of the study was to find the prevalence of eCRSwNP and neCRSwNP, their clinical comparison and to establish predictive values for clinical and diagnostic factors to differentiate between eCRSwNP and neCRSwNP in Indian population with CRSwNP. This study was a prospective cohort, multi- institutional study. A total of 162 patients who were diagnosed with nasal polyps at different military hospitals in India during the period from 2011 to 2020 were selected for study. They were diagnosed in accordance with EPOS guidelines. They were randomly divided into two groups as eCRSwNP and neCRSwNP based on the response to oral corticosteroids for 2 weeks duration and the prevalence of eCRSwNP was established. Blood samples were collected and endoscopic sinus surgery was performed in all patients after atleast 2 months of last steroid dose. Preop CT scan scores, preop nasal endoscopy scores, preop blood eosinophil counts, preop tissue eosinophil counts were compared between the groups. Postop followup was done at 6 months by comparing CT scan scores and nasal endoscopy scores. Predictive values for clinical and diagnostic factors were established to diagnose eCRSwNP in Indian population. Out of a total 162 patients, 121 (74.6%) patients were classified into eCRSwNP and 41 (23.6%) into neCRSwNP out of a total of 162 patients with CRSwNP. CRSwNP was seen in the 4th decade. eCRSwNP was seen in the later part and neCRSwNP was seen in the early part. eCRSwNP was more common in males and neCRSwNP was more common in females. Smoking, asthma and aspirin intolerance were more commonly seen in eCRSwNP than neCRSwNP, p < 0.001, p = 0.020 respectively. Preop total CT scan score, preop bood absolute eosinophil count,preop blood eosinophil percentage, tissue eosinophil percentage, postop nasal endoscopy score, postop CT scan score were stastically significant in eCRSwNP, p < 0.001 except preop total nasal endoscopic score. Tissue absolute eosinophil count had best predictive accuracy plotted with receiver operating characteristic (ROC) curve analysis, area under curve (AUC) 0.923(95% CI, 0.876–0.970). The cutoff points determined to diagnose eCRSwNP were ≥ 15 for preop total CT scan score,  ≥ 378 × 10⁶/L for preop absolute blood eosinophil count,  ≥ 6.5% for preop blood eosinophil percentage,  ≥ 14% for tissue eosinophil percentage,  ≥ 16 for absolute tissue eosinophil count, ≥ 1 for 6 months postop total nasal endoscopy score,  ≥ 2 for 6 months postop total CT scan score. eCRSwNP and neCRSwNP are two distinct endotypes of nasal polyps present in Indian population with CRSwNP. Two thirds of the patients with nasal polyps were eCRSwNP and the prevalence in Indian population is more than the East Asian population but less than the Western population. There is a high chance of recurrence and treatment failures for eCRSwNP than neCRSwNP. The cutoff points for various non invasive diagnostic predictors are useful to diagnose the patients with eCRSwNP during the outpatient visits and hence plan for better treatment strategies.