Blood Eosinophil Count and Lund–Mackay Ethmoid Score as Predictors of Recurrence After Endoscopic Sinus Surgery in CRSwNP

ABSTRACT Objectives To evaluate the incremental prognostic value of blood eosinophil count (BEC) and Lund–Mackay (LM) ethmoid score beyond age and asthma for recurrence after endoscopic sinus surgery (ESS) in adults with chronic rhinosinusitis with nasal polyps (CRSwNP). Methods This retrospective cohort included adults with CRSwNP undergoing ESS from January 2022 to November 2024. The outcome was endoscopically confirmed recurrence. Cox models included age and asthma, then added BEC and LM ethmoid score. Performance was evaluated at 36 months and internally validated using 1000 bootstrap resamples. Results Among 157 patients, 51 (32.5%) experienced recurrence; 36‐month recurrence‐free survival was 72.5% (95% confidence interval [CI], 64.7%–78.9%). Earlier recurrence was associated with age (adjusted hazard ratio [HR] per 10 years, 1.26; 95% CI, 1.03–1.53), asthma (HR, 2.00; 95% CI, 1.03–3.90), BEC (HR per 0.1 × 10 9 /L, 1.23; 95% CI, 1.12–1.36), and LM ethmoid score (HR per point, 1.29; 95% CI, 1.13–1.47). Adding BEC and LM ethmoid score reduced the Akaike information criterion from 476.3 to 458.6 and 446.1. Apparent and optimism‐corrected 36‐month area under the curve values were 0.818 (bootstrap 95% interval, 0.747–0.896) and 0.804; corrected C‐index and Brier score were 0.756 and 0.154. Conclusion BEC and LM ethmoid score provided complementary information beyond age and asthma. External validation and recalibration are required before clinical use.