LOW RATE OF SWITCHING FROM NR-AXSPA TO R-AXSPA AFTER 10 YEARS OF FOLLOW UP IN EARLY AXIAL SPONDYLOARTHRITIS. DATA FROM DESIR COHORT
Authors: Anna Molto et al.
There is a debate on whether non-radiographic axSpA is an early stage of radiographic axSpA or rather an own entity. This study using data from the French DESIR cohort analyzed the proportion of patients with nr-axSpA that switched to r-axSpA (fulfilling the modified New York Criteria, mNY) during a 10 yr follow up. Patients with less than 3 yrs disease duration (early axSpA) were included. In the patients with available radiographs at baseline and 10 years (n=299) a total of 5.7% switched from nr-axSpA to r-axSpA. In the intention to follow this population (n=704) the probability of a switch to r-axSpA increased by 0.91% per year. The probability decreased to 0.48% after adjusting for TNF-Inhibitor use. Bone marrow edema at the SI-joint in the MRI at baseline was associated with a higher risk of switching to r-axSpA, Other baseline factors associated with mNY positivity were male sex, disease duration over 1.5 yrs and smoking (in HLA-B27+ pts).
This cohort study shows that only a low percentage of patients with early nr-axSpA change to r-axSpA status over 10 years. The large majority of patients with nr-axSpA will remain nr-axSpA. The fact that TNF-Inhibitor treatment was associated with a lower annual increase of probability to change, argues for a preventive effect on radiographic changes in the sacroiliac joints. This is also supported by the finding that bone marrow edema at the SI-joints in the MRI was associated with a higher probability to change to r-axSpA.