Fig. 3

Association of synovial irisin with radiographic progression according to the Kellgren-Lawrence (KL) criteria within each knee osteoarthritis inflammatory phenotype (KOIP). The panels show the boxplots and stripcharts for irisin by patient groups in each KOIP group separately according to the patients’ progression status, as well as the group medians and their corresponding 95% confidence intervals. The legends display the fold changes (FC) between the groups, their 95% confidence intervals (between brackets), and the p-value for group comparisons derived from a Mann-Whitney test. A positive FC indicates higher average levels of irisin in progressors while negative FCs represent higher irisin levels in stable patients. Irisin values are represented in a transformed scale according to Tukey’s ladder of powers to symmetrize their distribution and make them more suitable for graphical representation (transformation parameter, g = 0); y-axis labels are shown in the original scale. FC, fold change; pv, p-value; KL, Kellgren-Lawrence; KOIP, knee osteoarthritis inflammatory phenotype