Figure 4: Serum APRIL levels in patients with rheumatoid arthritis (RA; N=59), ankylosing spondylitis (AS; N=61) and healthy controls (HC; N=60). Results are mean ± SEM. Statistical analysis was performed using Kruskal-Wallis test for global difference (level of significance: 0.05) and then post hoc Dunn test for comparison between RA and HC and between AS and HC (level of significance: 0.016).