PRTN3 and rheumatoid arthritis: Morning stiffness (≥60 minutes) was significantly associated with RA in the EAC (OR 2.92, 95% CI 2.47 to 3.44) and ESPOIR (OR 2.33, 95% CI 1.59 to 3.44), also after additional adjustments for ACPA, RF, SJC, symptom duration and ESR (OR 1.72.