IL17A and chronic rhinosinusitis with nasal polyps: Similarly, Kim et al, in a study of 70 patients with CRSwNP, found IL-17A and IL-23 to be negatively correlated with age.56 Wang et al conducted a multi-centre study of 573 patients across 6 countries in Europe, Asia, and Australia and found geographical variation in biomarkers.17 IL-17 was increased in CRSwNP compared to CRSsNP and controls in Adelaide and Beijing, but increased in CRSsNP compared to CRSwNP and controls in Tochigi.