FRI0643 SPINE AND SACROILIAC JOINTS LESIONS ON MRI IN PATIENTS WITH EARLY AXIAL SPA: CORRELATION WITH CLINICAL AND DISEASE ACTIVITY INDICES IN 24-MONTHS FOLLOW UP (ITALIAN ARM OF SPACE STUDY)
Authors: Mariagrazia Lorenzin, Augusta Ortolan, Mara Felicetti, Pamela Polito, Stefania Vio, Marta Favero, Carmelo Lacognata, Roberta Ramonda
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Recently several studies have focused on the use of magnetic resonance imaging (MRI) that might facilitate early diagnosis and monitor the disease activity of axial spondyloarthritis (axSpA). <h3>Objectives</h3> Evaluate the prevalence of spine and pelvis MRI lesions in patients (pts) with low back pain (LBP) and suspected axSpA;investigate how MRI features evolve over time and relate to radiographic damage;identify the predictive factors for a more severe disease pattern with a higher probability of radiological progression. <h3>Methods</h3> Seventy-five pts with LBP (≥3 months, ≤2 years, onset ≤45 years) underwent a physical examination, questionnaires, laboratory tests, X-rays and MRI of the spine and sacroiliac joints (SIJ) at baseline (T0) and during a follow-up (FU) period of 24 months.Two expert rheumatologists defined axSpA diagnosis and assessed fulfilment of Assessment of SpondyloArthritis International Society ASAS criteria.Disease activity and physical functioning were assessed using: Bath Ankylosing Spondylitis Metrology Index (BASMI);Maastricht Ankylosing enthesitis Spondilities Score (MASES);Bath Ankylosing Spondylitis Disease Activity Index (BASDAI);Bath Ankylosing Spondylitis Functional Index (BASFI);Ankylosing Spondylitis disease activity score (ASDAS);Visual Analogue Scale (VAS pain);VAS night pain;VAS disease activity;Bath Ankylosing Spondylitis Patient Global Score (BASG1);BASG2;Health Assessment Questionnaire (HAQ);ESR;serum ultrasensitive CRP (hs-CRP).Spine and SIJ MRI and X-rays were scored independently by 2 readers following the SPARCC, mSASSS and score SIJ-mNY.Pts were classified in accordance ASAS criteria as:21 pts classified according to axSpA imaging arm;29 pts classified according to axSpA clinical±imaging arm;25 pts not fulfilling ASAS criteria.The Kruskal Wallis test was used to compare all indices during FU.A regression analysis was performed to identify the predictors of inflammation and radiological progression of the disease evaluated using mSASSS, score SIJ-mNY, SPARCC-SIJ and SPARCC-spine.The following independent variables were considered in this analysis:female sex,age of LBP onset,duration of LBP,presence of HLA-B27, elevated ESR/CRP, BASDAI&gt;4, use of NSAIDs. <h3>Results</h3> The median LBP onset was 28.51±8.05 years, 45.3% were male, HLA-B27 was positive in 38.7% pts; 56% pts showed bone marrow edema (BME) in spine-MRI (19%,39%,33% in cervical/thoracic/lumbar region) and 61.3% pts in SIJ-MRI (respectively 58% on the right SIJ and 50% on the left SIJ).Signs of enthesitis were found in 62.7% pts (respectively 8%,58%,11% in the cervical/thoracic/lumbar spine).Eigtheen (24%) pts presented a negative BME SIJ-MRI with a positive BME spine-MRI.Predictive factors of increased radiological activity were, respectively, for a higher SPARCC-spine score, a higher use of NSAIDs and for a higher SPARCC-SIJ score, the presence of HLA-B27 and increased ESR/CRP.The prevalence of BME lesions on MRI and SPARCC-SIJ decreased during the FU period in the 2 cohorts that met the ASAS criteria for axSpA (<b>Table 1</b>, Figure 1a-b). <h3>Conclusion</h3> At T0 a significant prevalence of BME lesions was observed both for SIJ and the spine, with predominant involvement of thoracic district.Since positive spine-MRI images were observed in absence of sacroiliitis, we can hyphothesize that this finding could have a diagnostic significance in suspected axSpA.Further studies are warranted to assess in a more exhaustive manner the role of imaging in the monitoring of activity disease and radiological progression. <h3>Disclosure of Interests</h3> None declared