<scp>CBC</scp> ‐Derived Biomarkers Associated With Recurrence After Sinus Surgery in Chronic Rhinosinusitis

OBJECTIVE: Recurrence of chronic rhinosinusitis (CRS) after endoscopic sinus surgery (ESS) is common; however, biomarkers for long-term risk stratification remain limited. We examined associations between complete blood count (CBC)-derived biomarkers and long-term CRS recurrence after ESS. METHODS: A retrospective cohort of 543 CRS patients undergoing ESS was analyzed using time-to-event methods. Prespecified variables comprised CBC-derived biomarkers: absolute eosinophil count (AEC); eosinophil-to-lymphocyte, -monocyte, and -neutrophil ratios; monocyte-, neutrophil-, basophil-, and platelet-to-lymphocyte ratios; systemic immune-inflammation index (SII); systemic inflammation response index; and red cell distribution width, together with prespecified clinical covariates. Variable selection was performed using LASSO-penalized Cox regression with multicollinearity screening, followed by multivariable Cox modeling to estimate adjusted hazard ratios (HRs). Incremental prognostic value and longitudinal patterns were assessed. RESULTS: A total of 254 patients (46.8%) developed recurrence. In the multivariable model, higher AEC (HR: 2.868) and SII (HR: 1.320) were associated with recurrence, along with shorter symptom duration, asthma, NSAID hypersensitivity, nasal polyps, and higher Lund-Mackay scores. Addition of AEC improved model discrimination (C-index 0.778-0.797; ΔC = 0.019; p < 0.001), whereas SII provided minimal additional value (C-index 0.797-0.798; ΔC = 0.001; p = 0.513). In longitudinal analyses, baseline AEC and SII were associated with recurrence, but their changes over time did not differ between groups, with no significant temporal trends. CONCLUSION: Higher AEC and SII were independently associated with long-term CRS recurrence after ESS, with AEC providing greater incremental prognostic value than SII. These markers may reflect underlying host predisposition rather than dynamic disease activity.