In the mixed cohort of 53 RA and AS patients, PON activity only numerically increased after 6 months (121.0 ± 87.4 U/L; p = 0.107) and 12 months (120.1 ± 82.6 U/L; p = 0.140) compared to baseline (114.1 ± 79.3 U/L) (Figure 1A). Here, PON1 is linked to rheumatoid arthritis.