When these factors were introduced into a multivariate model, only age, gender, asthma comorbidity, prior surgery, bilateral CT scores, tissue neutrophil counts, blood eosinophil counts, and tissue IL-13 levels were significantly and independently associated with difficult-to-treat disease in patients with CRSwNP (Figure 7B). The gene discussed is IL13; the disease is chronic rhinosinusitis with nasal polyps.