Oral Steroid Use and Asthma Comorbidity in Central Compartment Atopic Disease: The Predictive Role of Olfactory Dysfunction and Eosinophilia

BACKGROUND: Central compartment atopic disease (CCAD) is a distinct phenotype of chronic rhinosinusitis with nasal polyps (CRSwNP), characterized by central nasal cavity inflammation. Although well described in Western populations, data from East Asia remain limited. We aimed to characterize CCAD's clinical features, identify predictors of postoperative oral corticosteroid (OCS) use, and explore CCAD's association with comorbid asthma. METHODS: In this propensity score-matched case-control study, patients with bilateral CRSwNP were classified as CCAD or non-CCAD using endoscopic findings. Clinical characteristics, laboratory markers, and surgical outcomes were compared. Subgroup analysis within CCAD evaluated predictors of postoperative OCS use and comorbid asthma. RESULTS: Compared with non-CCAD CRSwNP, CCAD patients had more severe subjective olfactory dysfunction (p = 0.035) and a distinct allergic inflammatory profile, including higher blood and tissue eosinophils, serum immunoglobulin E, and eosinophil cationic protein. Within the CCAD cohort, patients requiring postoperative OCS use had greater tissue eosinophilia; a threshold of ≥ 21 cells/high-power field independently predicted OCS need (hazard ratio = 12.4, 95% confidence interval = 1.6-93.4, p = 0.015). Comorbid asthma was associated with higher Lund-Mackay scores and blood eosinophilia (p = 0.012 and p = 0.007, respectively). CONCLUSIONS: CCAD is associated with greater subjective olfactory dysfunction and a distinct allergic inflammatory profile. Tissue eosinophilia independently predicts postoperative corticosteroid use, while advanced disease and elevated blood eosinophils predict comorbid asthma. These findings support risk stratification and personalized postoperative management in CCAD.