Predictive Value of Blood Eosinophil Ratio for Risk Stratification in Patients With Eosinophilic Chronic Rhinosinusitis With Nasal Polyps.

Background: Eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) is associated with severe symptoms and poor outcomes, but the diagnostic criteria remain elusive. The objective of this study is to identify preoperative predictors of ECRSwNP using multiple diagnostic thresholds and to propose a clinically actionable risk stratification model. Methods: A retrospective analysis was conducted on 1081 CRSwNP patients who underwent endoscopic sinus surgery. Receiver operating characteristic (ROC) curves were generated to predict ECRSwNP based on clinical features and identify reliable predictors. Results: Both the blood eosinophil count and ratio were identified as indicators for predicting ECRSwNP. The ratio exhibited the strongest correlation with that of tissue (r = 0.401, p < 0.001). The optimal blood eosinophil ratio cutoffs exhibited variability according to tissue-based criteria, ranging from 2.65% to 4.65%. For blood eosinophil ratios, thresholds of 2.65% (for > 10% tissue ratio) and 3.85% (for > 27% tissue ratio) exhibited divergent predictive profiles: the former yielded high positive predictive value (PPV = 79.87%), while the latter yielded high negative predictive value (NPV = 84.39%). To reconcile conflicting PPV/NPV profiles between thresholds, we defined a threshold of 3.25% (median between 2.65% and 3.85%). Patients could be divided into a group with a low risk(LR-ECRSwNP) for being defined as ECRSwNP and another group with a high risk(HR-ECRSwNP), of which the median values with interquartile ranges (IQRs) were 15.20 (2.20, 31.50)/HPF and 12.06 (1.84, 21.77)% tissue eosinophils for the low risk group and 30.67 (16.53, 77.90)/HPF and 23.92 (14.09, 45.66)% tissue eosinophils for the high risk group. The HR-ECRSwNP demonstrated significantly higher tissue eosinophil counts and ratios than the LR-ECRSwNP (p < 0.001). Conclusion: Blood eosinophil ratio ≥ 3.25% identifies CRSwNP patients at high risk for eosinophilic inflammation, providing a preoperative stratification tool. While correlations between blood and tissue eosinophils were moderate, this threshold balances sensitivity and specificity across heterogeneous diagnostic criteria.