Evaluation of the predictive validity of the ASAS axial spondyloarthritis criteria in the DESIR cohort.

OBJECTIVES: To evaluate the predictive validity of the Assessment of SpondyloArthritis international Society (ASAS) axial spondyloarthritis (axSpA), Amor, European Spondylarthropathy Study Group (ESSG) and modified New York (mNY) classification criteria.

METHODS: Patients from the DESIR cohort (inflammatory back pain suggestive of axSpA for >3 months but <3 years duration), followed for up to 5 years. Positive predictive value (PPV) of the set of criteria collected at baseline (ASAS, and its arms, Amor, ESSG and mNY: fulfilled/not fulfilled) were tested against the rheumatologist's axSpA diagnosis (fulfilled/not fulfilled) after 5 years of follow-up.

RESULTS: In total, among the 708 patients included in the DESIR cohort at baseline, data on rheumatologist's diagnosis at 5 years was available in 411 patients; amongst them, 352 (85.6%) had an axSpA diagnosis according to the rheumatologist; 268 patients fulfilled the ASAS axial SpA (axSpA) criteria at baseline and of these, 245 were diagnosed as SpA after 5 years follow-up (PPV: 91%). The PPV of the ASAS "imaging" arm and "clinical" arm was 97% and 82%, respectively. Other criteria also showed similar PPV - Amor (91%), ESSG (90%) and mNY (99%).

CONCLUSIONS: Positive predictive validity of the ASAS criteria for axSpA (including both arms) at 5 years was excellent; it is worth noting that the performances of the other criteria were also very good in the DESIR cohort.