PO:02:019 | Incidence of Spondyloarthritis in a Cohort of Italian patients presenting with Acute Non-granulomatous Anterior Uveitis during a five-years follow-up period

Alessandra Rai¹, Niccolò Possemato^1|2, Giorgia Citriniti², Filippo Crescentiini², Marianna Oliva², Elena Bolletta³, Pietro Gentile³, Luca De Simone³, Fabrizio Gozzi³, Luca Cimino^1|3, Pierluigi Macchioni², Carlo Salvarani^1|2 | ¹Università di Modena e Reggio Emilia Modena, Italy; ²Unità di Reumatologia, Azienda USL-IRCCS Reggio Emilia, Reggio Emilia, Italy; ³Unità di Immunologia Oculare, Azienda USL-IRCCS Reggio Emilia, Reggio Emilia, Italy

Background and aim of the study. Non-granulomatous acute anterior uveitis (NGAU) is an inflammatory eye condition frequently associated with axial Spondyloarthritis (SpA). Given the known diagnostic delay of SpA in patients with uveitis, this study aimed to identify potential risk factors associated with SpA development and to evaluate the incidence over a follow-up period of approximately five years.

Methods. This prospective monocentric study enrolled consecutive patients affected by noninfectious and nontraumatic NGAU referred to the Ocular Immunology Unit between January 2016 and January 2019. All patients underwent ophthalmic evaluation and blood test, including HLA-B27 typing. Clinical and demographic data were obtained. They were then referred to a rheumatologist to assess a definitive diagnosis or exclusion of SpA. The rheumatological assessment included 66/66 peripheral joint count, Leeds Enthesitis Index (LEI), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) and disease activity/functionally indices for Bath Ankylosing Spondylitis (BASDAI, BASFI). A concomitant diagnosis of fibromyalgia was also evaluated using the Fibromyalgia Impact Questionnaire (FIQ). Patients underwent an ultrasound examination of the main anatomical entheses and lower limb joints to assess the presence respectively of enthesitis and/or arthritis. Patients with inflammatory back pain (IBP) underwent a magnetic resonance imaging (MRI) of the sacroiliac joints. SpA classification followed the Assessment of SpA international Society (ASAS) criteria into axial or peripheral SpA. Patients without SpA at baseline were followed for an average period of five years to assess the incidence of newly diagnosed SpA.

Results. 101 patients with NGAU were enrolled (Females/Males 61/40, mean age 45.6 +/- 12.8 years, BMI 24.9 +/- 4.9, mean disease duration 40 +/- 76.6 months). Eighteen (17,8%) had a prior SpA diagnosis, while sixteen (15.8%) newly received a diagnosis of SpA: nine (56%) after the first rheumatological evaluation, and seven (44%) during the follow-up period. The overall prevalence of SpA after the baseline visit was 26,7%, increasing to 33,6% by the end of the observational period, with an incidence rate of 19,5% over a median follow up of 53,3 months. In our cohort, HLA-B27 positivity did not significantly correlate with SpA development. As expected, the multivariate logistic regression for SpA diagnosis identified as significant predictive factors the presence of IBP and BASDAI>/=4. Ultrasound detection of active enthesitis in patients fulfilling the clinical ASAS criteria for SpA significantly increased the specificity of SpA diagnosis, even without MRI, although this was not confirmed on multivariate analysis.

Conclusions. Our results confirmed a high prevalence of undiagnosed SpA among NGAU patients, suggesting the importance of early rheumatologic referral in presence of musculoskeletal symptoms. Ultrasound evaluation could significantly increase the sensitivity in the diagnosis of SpA, even without MRI, supporting its use as a valuable diagnostic tool for timely intervention.