Background The natural history of axial non radiographic axial spondyloarthritis (SpA) is not well known
Objectives To evaluate the predisposing factors of radiographic SIJ progression in early SpA.
Methods Patients: inflammatory back pain of less than 3 years duration suggestive of axial SpA (DESIR cohort). Radiographic progression: change in the radiographic status according to the modified New York (mNY) criteria (e.g. a switch from a baseline non-radiographic to a 2 year positive radiographic status based on central reading, anonimyzation of the films, adjudication by a third reader in case of discordance regarding mNY criteria between the 2 readers. Baseline potential predisposing factors: gender, age, smoking status, HLA B27, BASDAI, Positive SIJ-MRI (presence of inflammation according to the ASAS definition, based on a central reading including 2 trained readers and adjudication by a third senior reader in case of discordance regarding ASAS definition between the 2 readers). Statistical analysis: multivariable analysis (logistic regression).
Results Of the 449 evaluated patients, 326 [(age: 34±9 years old, female sex: 59%, symptoms duration: 18±11 months)] had a non-radiographic status at baseline according to the mNY criteria evaluated by the central readers and 16 of them switched to a radiographic status at year 2.The table summarizes the findings related to the baseline predisposing factors picked up in the multivariable analysis:
Conclusions These data suggest that 1) the rate of structural progression is low in early axial non-radiographic SpA, 2) both genetic (HLA B27), environmental (smoking) and inflammatory (MRI positivity) factors might contribute to this radiographic progression.
Acknowledgements DESIR is gfinancially supported by unrestricted grants from PFIZER France and the French Sopciety of Rheumatology
Disclosure of Interest None declared