Performance of the classification criteria in patients with late-onset axial spondyloarthritis

To evaluate the performance of four different classification criteria for spondyloarthritis (SpA) in patients with late-onset symptoms and to compare the clinical, laboratory and radiographic outcomes among the patients with symptoms before and after 45 years of age.

A total of 329 patients with SpA were enrolled in this prospective cohort. Patients with psoriatic arthritis, reactive arthritis, colitis associated arthritis and peripheral or undifferentiated SpA were excluded. The remaining individuals were divided into two groups based on their ages at the time of onset of symptoms: from 16 to 45 years of age (adult-onset, A-O) and after 45 years of age (late-onset, L-O). The clinical data were collected, including BASDAI, BASFI, BASMI, mSASSS, ASDAS, as were concomitant diseases and medications, efficacy and safety data. The performance of four SpA classification criteria, including modified New York, ESSG, Amor and ASAS, was evaluated in both groups. p value <.05 was considered as significant.

Thirty-two patients (9.72%) had L-O axial SpA. Mean age of diagnosis and symptoms were 57.6 (8.0) years and 7.6 (5.1) years, respectively. L-O patients had statistically worse functional impairment and higher disease activity. However, they had lower radiographic sacroiliac and spine damage (p < .001).

Our data showed that almost 10% of the patients with SpA had late-onset of symptoms. Moreover, they had higher disease activity, worse physical function and lower spine radiographic damage than A-O SpA patients. Additionally, the ASAS classification criteria had the best performance and might be used in clinical practice.