2.2 Subjects and study design
The research workflow was summed up in Figure 1. CRSwNP patients who underwent endoscopic sinus surgery (ESS) were selected from the department of otolaryngology in the XXX from Jan 2015 to Dec 2017. CRSwNP was diagnosed in accordance with the European Position Paper on Rhinosinusitis and Nasal polyps (EPOS) 2012 guidelines (2). Excluding criteria: 1) patients with fungal sinusitis, cystic fibrosis, choanal polyps and odontogenic sinusitis. 2) patients without blood routine examination and tissue specimens. 3) patients without preoperative sinus CT. 4) patients under 16 years old. 5) patients after treatment of systemic or intranasal glucocorticoid within four weeks before ESS. Patients accompanied by asthma was diagnosed according to the Global Initiative for asthma guidelines (GINA)2014(13). Patients with allergic rhinitis(AR) was confirmed base on the Allergic Rhinitis and its impact on Asthma (ARIA) 2010 guideline(14). Data for peripheral blood eosinophil counts were obtained according to routine blood test. On the strength of our previous study, systemic eosinophilia was defined as the eosinophil number in peripheral blood ≥ 0.3×109/L(5). Lund-Kennedy endoscopic (L-K) scores were assessed by two otolaryngologists who were unaware of disease condition in the retrospective study.