IL37 and rheumatoid arthritis: In the subgroup analysis, both IL-17 and IL-23 were compared in different subgroups, such as younger versus elderly RA, male versus female, early versus advanced RA, seropositive versus seronegative, cDMARDs/steroid versus naive, etc. It was found that serum IL-17 levels were higher in the advanced disease group compared to the early disease group.