Diagnostic value of serum and tissue eosinophil in diagnosis of asthma among patients with chronic rhinosinusitis.

Background: Chronic rhinosinusitis (CRS) is one of the most common chronic inflammatory diseases of sinonasal mucosa. Asthma among CRS patients is often underdiagnosed which makes the management of CRS more challenging. Therefore, using serum and tissue eosinophil as an indicator and predictor of asthma in CRS patients is vital for further preventing recurrent and increasing the effectiveness of treatment for CRS.

Objective: To determine the association and diagnostic ability of serum and tissue eosinophils in the diagnosis of asthma among CRS patients.

Methods: A cross-sectional study was conducted involving 24 CRS patients with asthma and without asthma, respectively, from the Otorhinolaryngology clinic of two tertiary hospitals located on the East Coast of Peninsular Malaysia. Serum and tissue eosinophils (obtained from nasal polyp) levels between both groups were compared. Association between serum and tissue eosinophils with asthma was evaluated using logistic regression analysis, adjusting for important sociodemographic characteristics. The diagnostic ability of serum and tissue eosinophil was then evaluated by assessing the receiver operating characteristic curve.

Results: A total of 48 CRS patients with a mean [SD] age of 47.50 [14.99] years were included. Patients with asthma had significantly higher serum [0.48 vs 0.35 × 10/L] and tissue eosinophil [100 vs 8.5 per HPF] levels. Tissue eosinophils were found to be an independent predictor of asthma with adjusted OR 1.05, p < 0.001, after adjusting for age and serum eosinophils. The area under the receiver operating characteristic curve for serum eosinophil was 69.0%. At optimal cut-off value (0.375 × 10/L), the sensitivity and specificity for serum eosinophil was 75.0% and 70.8%. The area under the receiver operating characteristic curve for tissue eosinophil was 93.4%. At the optimal cut-off value (58.0 per HPF), the sensitivity and specificity for tissue eosinophils were 79.2% and 91.7%, respectively.

Conclusion: This study indicates a significantly higher level of serum and tissue eosinophils in CRS with asthma. However, there was no correlation between serum and tissue eosinophils in both group. Based on this study, the CRS patient needs to be screened for asthma if the level of serum eosinophil is > 0.375 × 10/L and tissue eosinophil > 58 per HPF.