Association Between Eosinophilic Chronic Rhinosinusitis and Bronchiectasis in a Japanese Cohort

Objective Chronic rhinosinusitis (CRS) frequently coexists with bronchiectasis. Among the CRS phenotypes, CRS with nasal polyps (CRSwNP), which is predominantly characterized by type 2 (T2) inflammation, has been associated with bronchiectasis in Western populations. However, CRSwNP exhibits substantial inflammatory heterogeneity in Asia. From an inflammatory perspective, eosinophilic chronic rhinosinusitis (ECRS), a clinically defined CRS phenotype reflecting T2-dominant inflammation, may be more relevant to bronchiectasis. However, this association remains unclear. Methods We retrospectively analyzed patients aged ≥ 16 years who underwent paranasal sinus computed tomography (CT) followed by chest CT at a tertiary care center. The patients were classified into three groups: non-CRS, non-ECRS CRS, and ECRS groups. The association between CRS phenotypes and the presence of bronchiectasis was evaluated. Results A total of 74 patients were included (non-CRS, n = 39; non-ECRS CRS, n = 24; and ECRS, n = 11). The prevalence of bronchiectasis differed significantly among the groups: 31% in non-CRS, 42% in non-ECRS CRS, and 91% in ECRS (p = 0.001). In the multivariable analysis, increasing age [odds ratio (OR), 1.04; 95% confidence interval (CI), 1.00-1.07; p = 0.030] and ECRS (OR, 11.3; 95% CI, 1.15-111; p = 0.038) were independently associated with bronchiectasis. Conclusions ECRS is associated with bronchiectasis. These findings suggest that T2-dominant upper airway inflammation may contribute to the structural changes in the lower airways.