Tissue eosinophilia in chronic sinusitis: quantification techniques.

OBJECTIVE To ascertain the reliability of a proposed method for quantifying tissue eosinophilia in sinus mucosa. DESIGN Prospective cohort study. INTERVENTIONS AND OUTCOME MEASURES Pathology slides from patients undergoing endoscopic sinus surgery for chronic rhinosinusitis were independently assessed by 2 reviewers. Using a proposed systematic counting method, the degree of tissue eosinophilia was quantified. Disease severity was assessed by computed tomographic (CT) staging. Intrarater, interrater, and intrapatient reliability was determined using correlational reliability analysis. The degree of correlation between tissue eosinophilia and CT stage was determined. RESULTS One hundred thirty-two slides from 65 patients were reviewed. The mean (SD) eosinophil density was 23.4 (37.2) eosinophils per high-power field. Only 12 patients (18%) had no eosinophils on histopathologic analysis. Strong intrarater (r> or =0.91 for each rater, P<.001) and interrater reliability (r> or =0.82 between raters, P<.001) was noted for the quantification method. A moderate degree of correlation was found between CT scan stage and degree of tissue eosinophilia (Spearman rho = 0.62, P<.001). CONCLUSIONS The proposed method for quantifying tissue eosinophilia in sinus mucosa is reliable and valid. A relatively strong correlation exists between CT scan stage and tissue eosinophilia in chronic rhinosinusitis.