Early Axial Spondyloarthritis Detection: Two-Year Follow-up of the Sp-EYE Study on Acute Anterior Uveitis and Chronic Back Pain Screening.

Objective: In the previous Spondyloarthritis EYE study, we confirmed the potential of a screening strategy for early axial spondyloarthritis (axSpA) detection using acute anterior uveitis (AAU) and chronic back pain (CBP) as referral criteria. This follow-up study assessed changes in diagnostic categories (definite, suspected, and no axSpA) over 2 years and identified baseline factors predicting axSpA diagnosis at 24 months.

Methods: Patients with AAU and CBP were categorized into 3 groups: definite axSpA, suspected of axSpA, and no axSpA, based on clinical and radiographic data within 6 months after baseline. Suspected cases were monitored for 24 months, with the possibility of reclassification. A competing risk analysis was used to estimate the probability of transitioning from "suspected of axSpA" to "definite axSpA" or "no axSpA," and logistic regression analysis was employed to determine if baseline factors could predict definite axSpA at 24 months.

Results: Among 81 patients, 26 were classified as no axSpA, 36 as suspected of axSpA, and 19 as definite axSpA. At 24 months, suspected patients had an 18% probability to transition to definite axSpA (4 cases) and a 60% to no axSpA (15 cases). Significant predictors of axSpA diagnosis included the following: HLA-B27 positivity, good response to nonsteroidal anti-inflammatory drugs, inflammatory back pain, increasing C-reactive protein levels, buttock pain, and higher Bath Ankylosing Spondylitis Metrology Index scores.

Conclusions: Our screening strategy identified approximately one third of previously undiagnosed axSpA cases among patients with AAU and CBP, mostly at baseline, with few additional cases at follow-up. The predictors revealed in this study could aid physicians in estimating axSpA disease probability.