POS0029 ENHANCING THE DIAGNOSTIC ACCURACY AND AVOIDING OVERDIAGNOSIS IN AXIAL SPONDYLOARTHRITIS THROUGH CENTRAL EVALUATION OF IMAGING: IMPROVE-axSpA, A NATIONWIDE TELEMEDICINE PROJECT

Background: Axial spondyloarthritis (axSpA) is often diagnosed late, while there is also a problem of over- and misdiagnosis in patients with chronic back pain. Imaging, especially magnetic resonance imaging (MRI), is important for diagnosis and differential diagnosis, but interpreting imaging findings in sacroiliac joints requires specific expertise. Objectives: The Improve-axSpA project was aimed to assess the effectiveness of telemedicine support in enhancing the diagnostic accuracy of patients suspected of having axSpA. Methods: We established a central telemedicine platform that allowed the collection of clinical and imaging information from patients who presented to rheumatologists and orthopaedists with suspicion of axSpA in Germany and Austria. Participating centres were encouraged to recruit appropriate patients consecutively. Collected information included the suspected diagnosis and imaging findings, demographic and laboratory data, information on potential mechanical stress factors, characteristics of back pain and SpA features as assessed by the local physician. The central expert evaluation included detailed assessment of the submitted data including imaging and the final conclusion on the presence or absence of axSpA. Results: A total of 40 study centres submitted 476 cases for the central evaluation until November 2023. The distribution of the diagnoses according to the local and central assessment is presented in Table 1. A total of 134/476 patients (28%) were locally diagnosed with axSpA. Only in 69 (51.5%) of those cases axSpA could be confirmed after central evaluation, while in 47 patients (35.1%) an alternative reason of back pain (in the majority of cases Degenerative/ mechanical disorders, non-specific back pain) were found to be more likely. In contrast, among 159 patients with no axSpA according to local assessment, in 136 (85.5%) no axSpA was confirmed by central evaluation. In 183 cases with inconclusive local diagnosis, axSpA was more frequently excluded than confirmed (75% vs. 16%). In a total of 46 patients, the diagnosis could not be finally determined after central assessment, this being related in most cases to insufficient imaging. Several important differences could be found between patients with centrally confirmed vs. excluded axSpA: patients without SpA were older, more often females (and more often with a history of pregnancies and more deliveries), had lower CRP, higher BMI and were less frequently HLA-B27-positive (see Table 2). At the same time, other SpA-characteristics including inflammatory back pain, as well as imaging characteristics as reported by the local rheumatologist were not discriminative between the groups. However, the presence or absence of SpA compatible active inflammatory and structural changes on MRI of sacroiliac joints according to the central assessment were highly discriminative between the groups with confirmed and excluded SpA (Table 2). Conclusion: These data suggest a high risk of overdiagnosis of SpA in daily clinical practice. Telemedicine tools with central evaluation of clinical and imaging information may be helpful in the diagnostic process for patients with suspected axSpA. Correct identification of axSpA or its exclusion is heavily but not solely depended on imaging and requires expertise by both rheumatologists and radiologists with accessible information to all clinical and imaging outcomes. REFERENCES: NIL. Acknowledgements: The study is supported by Novartis Pharma GmbH. We thank all participating physicians and patients. Disclosure of Interests: Denis Poddubnyy AbbVie, Canon, DKSH, Eli Lilly, Janssen, MSD, Medscape, Novartis, Peervoice, Pfizer, and UCB, AbbVie, Biocad, Bristol-Myers Squibb, Eli Lilly, Janssen, Moonlake, Novartis, Pfizer, and UCB, AbbVie, Eli Lilly, MSD, Novartis, Pfizer, Marc Kämmerer: None declared, Marcus Kremers: None declared, Annette Wiedon Novartis Pharma GmbH, Imke Redeker: None declared, Xenofon Baraliakos AbbVie, Amgen, Bristol Myers Squibb, Chugai, Galapagos, Gilead, Lilly, MSD, Novartis, Pfizer, Roche, Sandoz, and UCB.