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Ankylosing spondylitis (AS) is the historic term used for decades for the HLA-B27-associated inflammatory disease affecting mainly the sacroiliac joints (SIJ) and spine. Classification criteria for AS have radiographic sacroiliitis as a dominant characteristic. However, with the availability of MRI of SIJ, it could be demonstrated that the disease starts long before definite SIJ changes become visible on radiographs. The Assessment of SpondyloArthritis international Society, representing a worldwide group of experts reached consensus on changes in the nomenclature pertaining to axial spondyloarthritis (axSpA), such as the terminology of diagnosis and of assessment of disease activity tools. These are important changes in the field, as experts in axSpA are now in agreement that the term axSpA is the overall term for the disease. A further differentiation, of which radiographic versus non-radiographic is only one aspect, may be relevant for research purposes. Another important decision was that the terms AS and radiographic axSpA (r-axSpA) can be used interchangeably, but that the preferred term is r-axSpA. Based on the decision that axSpA is the correct terminology, a proposal was made to officially change the meaning of the ASDAS acronym to 'Axial Spondyloarthritis Disease Activity Score'. In addition, for simplification it was proposed that the term ASDAS (instead of ASDAS-CRP) should be preferred and applied to the ASDAS calculated with C reactive protein (CRP). It is hoped that these changes will be used consequently for education, in textbooks, manuscripts and presentations., Competing Interests: Competing interests: DvdH has received consulting fees from AbbVie, Argenx, Bayer, BMS, Galapagos, Gilead, GlaxoSmithKline, Janssen, Lilly, Novartis, Pfizer, Takeda, UCB Pharma. She is Director of Imaging Rheumatology bv, associate editor of ARD, editorial board member of J Rheumatol and RMD Open, advisor of ASAS. AM has received consulting fees from AbbVie, Amgen, BMS, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, UCB Pharma and Viatris. SR has received research grants and/or consulting fees from AbbVie, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, UCB, Sanofi. MD has received consulting fees from Pfizer, AbbVie, UCB, Amgen, BMS, Galapagos, Lilly, Novartis, Merck. FAvG has received consultation fees from Novartis, BMS, AbbVie, MSD, Janssen, Lily, UCB. LG has received research grants and/or consulting fees from AbbVie, Acelyrin, Eli Lilly, Fresenius Kabi, Janssen, Novartis, Pfizer, UCB. RDI has received consulting fees from Abbvie, Janssen, Novartis, UCB. RBML has received consulting fees from AbbVie, BMS, Galapagos, Eli-Lilly, Novartis, Jansen, Pfizer and UCB, is director of Rheumatology Consultancy BV and past-president and executive member of ASAS. HM-O has received grant support from Janssen, Novartis and UCB. Honoraria and/or speaker fees from AbbVie, Biogen, Eli-Lilly, Janssen, Moonlake, Novartis, Pfizer, Takeda and UCB. VN-C has received consultancy/speaker/research grants from Abbvie, BMS, Fresenius Kabi, Galapagos, Janssen, Lilly, Moonlake, MSD, Novartis, Pfizer, Roche, UCB. AP, Patient with AxSpa, Eupati Fellow, Patient Expert, Advocator, President of Cyprus League of People with Rheumatism, President of AGORA Federation, Secretary of Axial Spondylarthritis International Federation (ASIF), EULAR-Advocacy Committee Member-Pare Committee Member. DP has received research support from AbbVie, Eli Lilly, MSD, Novartis, Pfizer, consulting fees from AbbVie, Biocad, Bristol-Myers Squibb, Eli Lilly, Janssen, Moonlake, Novartis, Pfizer and UCB, and speaker fees from AbbVie, Canon, DKSH, Eli Lilly, Janssen, MSD, Medscape, Novartis, Peervoice, Pfizer and UCB. MP has received consulting fees from Novartis as well as support for attending meetings and/or travel from Abbvie, Jannsen, Novartis and UCB. MR has receieved consulting/speaker fees from Abbvie, Chugai, Boehringer, Eli-Lilly, Janssen, Novartis, UCB. PDS-B has received consulting/ speaker's fees from AbbVie, Celltrion, Eli Lilly, GSK, Janssen, Novartis, Pfizer and UCB. AS has received speaking and/or consulting fees from Abbvie, Novartis, UCB and Lilly. JS has received gees for consultancies and for being a member of speakers’ bureau from Abbvie, Merck, Novartis and UCB. FEVdB has received consulting fees from Abbvie, Amgen, Eli Lilly, Galapagos, Janssen, Moonlake, Novartis and UCB. IvdH-B has received consulting/speaker’s fees from UCB, Lilly, AbbVie, MSD, BMS, Novartis. PMM has received consulting/speaker’s fees from Abbvie, BMS, Celgene, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Orphazyme, Pfizer, Roche and UCB. XB has received consulting/speaker’s fees Abbvie, Amgen, BMS, Chugai, Galapagos, Gilead, Lilly, MSD, Novartis, Pfizer, Roche, Sandoz, UCB, Zuellig Pharma and is Member of the Editorial Board of ARD, ASAS President and EULAR President Elect., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ on behalf of EULAR.)

Background: Radiographic progression and course of inflammation over 2 years in patients with non-radiographic axial spondyloarthritis (nr-axSpA) from the phase 3, randomized, PREVENT study are reported here., Methods: In the PREVENT study, adult patients fulfilling the Assessment of SpondyloArthritis International Society classification criteria for nr-axSpA with elevated CRP and/or MRI inflammation received secukinumab 150 mg or placebo. All patients received open-label secukinumab from week 52 onward. Sacroiliac (SI) joint and spinal radiographs were scored using the modified New York (mNY) grading (total sacroiliitis score; range, 0-8) and modified Stoke Ankylosing Spondylitis Spine Score (mSASSS; range, 0-72), respectively. SI joint bone marrow edema (BME) was assessed using the Berlin Active Inflammatory Lesions Scoring (0-24) and spinal MRI using the Berlin modification of the AS spine MRI (ASspiMRI) scoring (0-69)., Results: Overall, 78.9% (438/555) of patients completed week 104 of the study. Over 2 years, minimal changes were observed in total radiographic SI joint scores (mean [SD] change, - 0.04 [0.49] and 0.04 [0.36]) and mSASSS scores (0.04 [0.47] and 0.07 [0.36]) in the secukinumab and placebo-secukinumab groups. Most of the patients showed no structural progression (increase ≤ smallest detectable change) in SI joint score (87.7% and 85.6%) and mSASSS score (97.5% and 97.1%) in the secukinumab and placebo-secukinumab groups. Only 3.3% (n = 7) and 2.9% (n = 3) of patients in the secukinumab and placebo-secukinumab groups, respectively, who were mNY-negative at baseline were scored as mNY-positive at week 104. Overall, 1.7% and 3.4% of patients with no syndesmophytes at baseline in the secukinumab and placebo-secukinumab group, respectively, developed ≥ 1 new syndesmophyte over 2 years. Reduction in SI joint BME observed at week 16 with secukinumab (mean [SD], - 1.23 [2.81] vs - 0.37 [1.90] with placebo) was sustained through week 104 (- 1.73 [3.49]). Spinal inflammation on MRI was low at baseline (mean score, 0.82 and 1.07 in the secukinumab and placebo groups, respectively) and remained low (mean score, 0.56 at week 104)., Conclusion: Structural damage was low at baseline and most patients showed no radiographic progression in SI joints and spine over 2 years in the secukinumab and placebo-secukinumab groups. Secukinumab reduced SI joint inflammation, which was sustained over 2 years., Trial Registration: ClinicalTrials.gov, NCT02696031., (© 2023. The Author(s).)

Objectives: To compare MRI and conventional radiography of SI joints for detection of structural lesions typical for axial spondyloarthritis (axSpA)., Methods: Adult patients from the Assessment of SpondyloArthritis international Society (ASAS) cohort with symptoms suggestive of axSpA and both SI joint MRI and radiographs available for central reading were included. Radiographs were evaluated by three readers according to the modified New York (mNY) criteria grading system. The presence of structural damage on radiographs was defined as fulfilment of the radiographic mNY criterion and, additionally, a lower threshold for sacroiliitis of at least grade 2 unilaterally. MRI scans were assessed for the presence of structural changes indicative of axSpA by seven readers. Diagnostic performance [sensitivity, specificity, positive and negative predictive values (PPV and NPV) and positive and negative likelihood ratios (LR+ and LR-)] of MRI and radiographs (vs rheumatologist's diagnosis of axSpA) were calculated., Results: Overall, 183 patients were included and 135 (73.7%) were diagnosed with axSpA. Structural lesions indicative of axSpA on MRI had sensitivity 38.5%, specificity 91.7%, PPV 92.9%, NPV 34.6%, LR+ 4.62 and LR- 0.67. Sacroiliitis according to the mNY criteria had sensitivity 54.8%, specificity 70.8%, PPV 84.1%, NPV 35.8%, LR+ 1.88 and LR- 0.64. Radiographic sacroiliitis of at least grade 2 unilaterally had sensitivity 65.2%, specificity 50.0%, PPV 78.6%, NPV 33.8%, LR+ 1.30 and LR- 0.69., Conclusion: Structural lesions of the SI joint detected by MRI demonstrated better diagnostic performance and better interreader reliability compared with conventional radiography., (© The Author(s) 2022. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

The possibility of detection of structural damage on magnetic resonance imaging (MRI) of sacroiliac joints raises the question of whether MRI can substitute radiographs for diagnostic evaluation and to a further extent for classification of axial spondyloarthritis (axSpA). In this viewpoint, we will argue that it is time to replace conventional radiographs with MRI for the assessment of structural changes in sacroiliac joints. This message is based on current data on the following questions: (1) How reliable are conventional radiographs in the diagnosis of axSpA overall and radiographic axSpA in particular? (2) How does T1-weighted MRI compare to radiographs in the detection of sacroiliitis? (3) Are there now other (better) MRI sequences than T1-weighted, which might be more suitable for the detection of structural lesions? (4) Which MRI sequences should be performed for the diagnostic evaluation of the sacroiliac joints? (5) Do we have data to define sacroiliitis based on structural changes detected by MRI?, Competing Interests: Competing interests: DP: research support from AbbVie, Eli Lilly, MSD, Novartis and Pfizer; consulting fees from AbbVie, Biocad, Eli Lilly, Galapagos, Gilead, GlaxoSmithKline, Janssen, MSD, Moonlake, Novartis, Pfizer, Samsung Bioepis and UCB; speaker fees from AbbVie, Bristol-Myers Squibb, Eli Lilly, Janssen, MSD, Medscape, Novartis, Peervoice, Pfizer and UCB. TD: research grants to the institution from Canon MS and the Berlin Institute of Health; consulting and lecture fees from Eli Lilly, Novartis, MSD, Roche and Canon MS. XB: grants from Abbvie, BMS, Eli-Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, Roche, Sandoz, Sanofi and UCB; consulting fees from Abbvie, BMS, Eli-Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, Roche, Sandoz, Sanofi and UCB; honoraria from Abbvie, BMS, Eli-Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, Roche, Sandoz, Sanofi and UCB; meeting attendance support from Abbvie, BMS, Eli-Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, Roche, Sandoz, Sanofi and UCB; leadership roles as editorial board member of Annals of Rheumatic Diseases, ASAS president. KGAH: consulting fees from AbbVie and lecture honoraria from Novartis, Pfizer and MSD; cofounder of BerlinFlame GmbH. JS: honoraria for consultancy or being a member of a speaker’s bureau from Abbvie, Novartis, MSD and UCB., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: To investigate the longitudinal association between radiographic sacroiliitis progression and treatment with tumor necrosis factor inhibitors (TNFi) in patients with early axial spondyloarthritis (SpA) in a long-term inception cohort., Methods: We included patients from the German Spondyloarthritis Inception Cohort who underwent radiographic assessment of the sacroiliac joints at baseline and at least once more during the 10-year follow-up. Two central readers scored the radiographs according to the modified New York criteria for ankylosing spondylitis. The sacroiliac sum score was calculated as a mean of the scores determined by both readers. TNFi use was assessed according to exposure in the current and/or previous 2-year radiographic interval. The association between TNFi use and radiographic sacroiliitis progression was examined by longitudinal generalized estimating equation analysis with adjustment for potential confounders., Results: In this long-term inception cohort, 10-year follow-up data on 737 radiographic intervals assessed in 301 patients with axial SpA (166 patients with nonradiographic axial SpA and 135 patients with radiographic axial SpA) were obtained. Having received ≥12 months of treatment with TNFi in the previous 2-year radiographic interval was associated with a significant decrease in the sacroiliitis sum score (β = -0.09 [95% confidence interval (95% CI) -0.18, -0.003]; analyses adjusted for age, sex, symptom duration, HLA-B27 status, Bath Ankylosing Spondylitis Disease Activity Index score, C-reactive protein, and nonsteroidal antiinflammatory drug intake). In contrast, among patients receiving TNFi in the current radiographic interval, there was no significant association with change in the sacroiliitis sum score (β = 0.05 [95% CI -0.05, 0.14]). This effect of having received ≥12 months of treatment with TNFi in the previous 2-year radiographic interval was stronger in patients with nonradiographic axial SpA as compared to patients with radiographic axial SpA (β = -0.16 [95% CI -0.28, -0.03] versus β = -0.04 [95% CI -0.15, 0.07])., Conclusion: Treatment with TNFi was associated with the reduction in radiographic sacroiliitis progression in patients with axial SpA. This effect became evident between 2 and 4 years after treatment was initiated., (© 2022 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Aim: To identify all possible definitions of "early SpA" employed in the literature, including "early axial SpA (axSpA)" and "early peripheral SpA (pSpA)"., Methods: A systematic literature review was conducted in Medline, EMBASE and the Cochrane Library for studies that included any mention of "early SpA" or its subtypes. The proportion of studies including a definition was calculated, and the different definitions were assessed., Results: Out of 9651 titles identified, 336 publications reporting data from 183 studies were included. Over time, an increasing number of publications were identified. In total, 114 (62%) studies reported a specific definition: 33% of them based it on symptom duration, 31% on radiographic damage, 28% on disease duration, 5% on both symptom/disease duration and radiographic damage, and 3% on other aspects. Overall, 61 (33%) studies included the term "early axSpA", whereas 60 (33%) included "early ankylosing spondylitis (AS)". Regarding the studies that referred to "early axSpA", the most used definition was symptom/disease duration <5 years, whereas for "early AS" was symptom/disease duration <10 years. After 2010, the definition of "early axSpA" based on the absence of radiographic sacroiliitis was less used compared to before 2010 (17% vs 38%)., Conclusion: Over time, the term "early SpA" and its subtypes is increasingly used. More than one third of the studies did not include a definition of the term and the studies reporting one showed a large heterogeneity. These results emphasize the need for a standardised definition of early SpA., (Copyright © 2022. Published by Elsevier Inc.)

Axial spondylarthritis in adulthood (SpAA) is frequently initially manifested as a sacroiliitis, whereas this not true for enthesitis-related arthritis (EAA), which begins in childhood and adolescence. Classically, EAA begins with peripheral arthritis and only a part transitions into a juvenile SpA (jSpA) or SpAA. The criteria used for classification of SpAA and EAA are currently being validated and revised. For the first time imaging is included for EAA. For both diseases nonsteroidal anti-inflammatory drugs (NSAID) are initially used therapeutically, followed by biologicals or synthetic targeted disease-modifying drugs in refractory courses. Steroids should be avoided in long-term treatment. For optimal transition and further care in adulthood, a close cooperation between internistic and pediatric rheumatologists is necessary., (© 2022. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Objectives: To propose a data-driven definition for structural changes of sacroiliac (SI) joints in the context of axial spondyloarthritis (axSpA) imaging on a large collective of CT datasets., Methods: 546 individuals (102 axSpA, 80 non-axSpA low back pain and 364 controls without back pain) with SI joint CTs were evaluated for erosions, sclerosis and ankylosis using a structured scoring system. Lesion frequencies and spatial distribution were compared between groups. Diagnostic performance (sensitivity (SE), specificity (SP), positive predictive values, negative predictive values and positive and negative likelihood ratios) was calculated for different combinations of imaging findings. Clinical diagnosis served as standard of reference., Results: Ankylosis and/or erosions of the middle and dorsal joint portions yielded the best diagnostic performance with SE 67.6% and SP 96.3%. Inclusion of ventral erosions and sclerosis resulted in lower diagnostic performance with SE 71.2%/SP 92.5% and SE 70.6%/SP 90.0%, respectively., Conclusions: Sclerosis and ventrally located erosions of SI joints have lower specificity on CT of the SI joint in the context of axSpA imaging. Ankylosis and/or erosions of the middle and dorsal joint portions show a strong diagnostic performance and are appropriate markers of a positive SI joint by CT., Competing Interests: Competing interests: KGAH reports lecture fees from AbbVie, MSD and Novartis outside the submitted work. KZ reports funding (research grant) from the Assessment of Spondyloarthritis international Society (ASAS) during the conduct of this study. DP reports grants and personal fees from AbbVie, Eli Lilly, MSD, Novartis, Pfizer and personal fees from Bristol-Myers Squibb, Roche, UCB, Biocad, GlaxoSmithKline, Gilead, Janssen, Samsung Bioepis and UCB outside the submitted work. FP reports grants and personal fees from Novartis, Lilly and UCB, as well as personal fees from AbbVie, AMGEN, BMS, Hexal, MSD, Pfizer and Roche outside the submitted work. JS reports personal fees from AbbVie, Janssen, Merck, Novartis, UCB and Lilly, outside the submitted work. TD reports funding (research grant) from the ASAS and lecture fees from Canon Medical, AbbVie, MSD and Novartis pharma, outside the submitted work. For all other authors, none were reported., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Psoriatic arthritis (PsA) is a heterogenous, chronic, inflammatory musculoskeletal disease that can lead to peripheral and axial damage and loss of function. Axial involvement occurs in 25% to 70% of patients with PsA, varying greatly depending on its definition, with the key manifestations being sacroiliitis and/or spondylitis. However, there are no agreed-upon classification or diagnostic criteria for axial involvement in PsA and no consensus on treatment paradigms, which complicates management of PsA. There have only been a few studies assessing biologics in patients with PsA with axial involvement, and most treatment plans are based on evidence from patients with axial spondyloarthritis. Rheumatologists therefore face many challenges in the management of axial PsA, including diagnosis, differential diagnosis, and choice of appropriate treatment. In this review, we summarize the clinical presentation, imaging characteristics, differential diagnoses, treatment options, and prognosis of axial PsA, with the aim of increasing rheumatologists' knowledge of this phenotype of PsA and thereby aiding its optimal management., Competing Interests: Declarations of Interest D. Poddubnyy has received research grants from AbbVie, Eli Lilly, MSD, Novartis, and Pfizer and has received consultancy or speaker fees from AbbVie, Biocad, Bristol Myers Squibb, Eli Lilly, Gilead, GlaxoSmithKline, Janssen, MSD, Novartis, Pfizer, Samsung Bioepis, and UCB. D.R. Jadon has received research grants from Pfizer, Eli Lilly, Merck, GSK, Biogen, and Celgene and has received educational grants from Novartis, Eli Lilly, Biogen, Gilead, Pfizer, UCB, AbbVie, Janssen, Amgen, Bristol Myers Squibb, Roche, and Celltrion; his research time was also partially funded by the Cambridge Arthritis Research Endeavour. F. Van den Bosch has received consultancy and/or speaker fees from AbbVie, Celgene, Eli Lilly, Galapagos, Gilead, GSK, Janssen, Novartis, Pfizer, and UCB. P.J. Mease has received research grants from Celgene, Novartis, AbbVie, Amgen, Bristol Myers Squibb, Gilead, Eli Lilly, Pfizer, Sun Pharma, and UCB; consulting fees from Celgene, Corrona, Novartis, AbbVie, Amgen, Boehringer Ingelheim, Bristol Myers Squibb, Galapagos, Gilead, GSK, Janssen, Eli Lilly, Merck, Pfizer, Sun Pharma, and UCB; and speakers bureau fees from AbbVie, Amgen, Janssen, Novartis, Pfizer, and UCB. D.D. Gladman has received research grants from AbbVie, Amgen, Celgene, Eli Lilly, Novartis, Pfizer, and UCB and consulting fees from AbbVie, Amgen, Bristol Myers Squibb, Celgene, Galapagos, Gilead, Janssen, Lilly, Novartis, Pfizer, and UCB., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: To determine the clinical profile of axial psoriatic arthritis (PsA) in a worldwide setting. Secondly, to identify factors associated with the development of axial involvement in patients with PsA., Methods: Data from 3684 patients with axial spondyloarthritis (axSpA) or PsA from the ASAS-perSpA study were analysed. The ASAS-perSpA is a cross-sectional study that recruited consecutive patients with SpA (as diagnosed by their rheumatologist) from 68 centers worldwide and collected patient and disease data. First, 2651 axSpA patients and 367 PsA patients with any history of axial involvement (axPsA) were compared using logistic regression to later identify predictive factors for rheumatologist diagnosis of axPsA. Secondly, 367 axPsA patients were compared with 666 PsA patients lacking axial involvement (peripheral PsA [pPsA]) and the characteristics associated with axial manifestations were explored by logistic regression analysis., Results: Patients with axPsA were older and less frequently males or HLA*B27 positive in comparison with axSpA patients. Additionally, while patients with axPsA had more peripheral manifestations and psoriasis, other extra-musculoskeletal manifestations (IBD and uveitis) were more frequent in those with axSpA. In the multivariable analysis, older age at diagnosis (OR = 1.04), peripheral arthritis (OR = 7.32) and dactylitis (OR = 2.82) were significantly associated with the diagnosis of axPsA. However, uveitis (OR = 0.22), IBD (OR = 0.12), HLA*B27 carriership (OR = 0.26) or sacroiliitis on imaging (OR = 0.5) were inversely associated with axPsA diagnosis as compared to axSpA. Axial involvement in patients with PsA was significantly associated with male gender (OR = 1.68), elevated CRP (OR = 2.87) and the absence of psoriasis (OR = 0.33)., Conclusion: In this worldwide setting axPsA was defined by rheumatologists as a unique phenotype, with disease features lying between axSpA and pure pPsA., Competing Interests: Declaration of Competing Interest Dr. Benavent received personal fees from Roche and personal fees from Abbvie, outside the submitted work. Dr. Plasencia-Rodríguez received research grants/honoraria from AbbVie, Lilly, Novartis, Pfizer, Sanofi, Biogen and UCB. Dr. Poddubnyy reports grants and personal fees from AbbVie, personal fees from Bristol-Myers Squibb, grants and personal fees from Eli Lilly, grants and personal fees from MSD, grants and personal fees from Novartis, grants and personal fees from Pfizer, personal fees from Roche, personal fees from UCB, personal fees from Biocad, personal fees from GlaxoSmithKline, personal fees from Gilead outside the submitted work. Dr. Kishimoto reports personal fees from AbbVie, personal fees from Amgen-Astellas BioPharma, personal fees from Ayumi Pharma, personal fees from BMS, personal fees from Chugai, personal fees from Daiichi-Sankyo, personal fees from Eisai, personal fees from Eli Lilly, personal fees from Gilead, personal fees from Janssen, personal fees from Kyowa Kirin, personal fees from Novartis, personal fees from Ono Pharma, personal fees from Pfizer, personal fees from Tanabe-Mitsubishi, personal fees from UCB Pharma, outside the submitted work. Dr. Proft reports personal fees from AbbVie, personal fees from AMGEN, personal fees from BMS, personal fees from Celgene, personal fees from MSD, grants and personal fees from Novartis, personal fees from Pfizer, personal fees from Roche, grants and personal fees from UCB, outside the submitted work. Dr. Sawada has nothing to disclose. Dr. López-Medina has nothing to disclose. Dr. Dougados has nothing to disclose. Dr. Navarro-Compán reports personal fees and other from ABBVIE, personal fees from MSD, grants, personal fees and other from NOVARTIS, personal fees and other from PFIZER, personal fees from UCB, personal fees from LILLY, outside the submitted work., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Radiographs of the sacroiliac joints are commonly used for the diagnosis and classification of axial spondyloarthritis. The aim of this study was to develop and validate an artificial neural network for the detection of definite radiographic sacroiliitis as a manifestation of axial spondyloarthritis (axSpA)., Methods: Conventional radiographs of the sacroiliac joints obtained in two independent studies of patients with axSpA were used. The first cohort comprised 1553 radiographs and was split into training (n = 1324) and validation (n = 229) sets. The second cohort comprised 458 radiographs and was used as an independent test dataset. All radiographs were assessed in a central reading session, and the final decision on the presence or absence of definite radiographic sacroiliitis was used as a reference. The performance of the neural network was evaluated by calculating areas under the receiver operating characteristic curves (AUCs) as well as sensitivity and specificity. Cohen's kappa and the absolute agreement were used to assess the agreement between the neural network and the human readers., Results: The neural network achieved an excellent performance in the detection of definite radiographic sacroiliitis with an AUC of 0.97 and 0.94 for the validation and test datasets, respectively. Sensitivity and specificity for the cut-off weighting both measurements equally were 88% and 95% for the validation and 92% and 81% for the test set. The Cohen's kappa between the neural network and the reference judgements were 0.79 and 0.72 for the validation and test sets with an absolute agreement of 90% and 88%, respectively., Conclusion: Deep artificial neural networks enable the accurate detection of definite radiographic sacroiliitis relevant for the diagnosis and classification of axSpA.

Secondary hyperparathyroidism (sHPT) as a result of chronic kidney disease (CKD) is a common health problem and has been reported to manifest at the sacroiliac joints (SIJ). The aim of this investigation was to systematically assess sacroiliac joint changes in asymptomatic sHPT as detected by high-resolution CT. Included in this IRB-approved retrospective case-control study were 56 patients with asymptomatic sHPT as well as 259 matched controls without SIJ disease. Demographic data were retrieved from electronic patient records. High-resolution computed tomography datasets of all patients were subjected to a structured scoring, including erosions, sclerosis, osteophytes, joint space alterations and intraarticular calcifications. Chi 2 tests were used to compare frequencies of lesions. Erosions were significantly more prevalent in patients with sHPT, and were found mainly in the ventral (28.6% vs. 13.9%; p = 0.016) and middle (17.9% vs. 7.7%; p = 0.040) iliac portions of the SIJ. Partial ankylosis was rare in both cohorts (3.6% vs. 5.0%; p > 0.999); complete ankylosis was not observed. Neither extent not prevalence of sclerosis or calcifications differed significantly between groups. Joint lesions reminiscent of sacroiliitis can be found in a substantial portion of asymptomatic patients with secondary hyperparathyroidism. Further investigations into the clinical significance of these findings are warranted.

Objective: The aim was to investigate the reliability and validity of radiographic sacroiliitis assessment in anteroposterior (AP) lumbar radiographs compared with conventional pelvic radiographs in patients with axial spondyloarthritis (axSpA)., Methods: Patients from the German Spondyloarthritis Inception Cohort were selected based on the availability of pelvic and AP lumbar radiographs with visible SI joints at baseline and year 2. Two readers scored the images independently in a random order according to the modified New York criteria. The sacroiliitis sum score was calculated as the mean of both readers. Patients were classified as radiographic (r-)axSpA if radiographic sacroiliitis of grade ≥2 bilaterally or grade ≥3 unilaterally was present in the opinion of both readers and as non-radiographic (nr-)axSpA otherwise. The reliability and validity of sacroiliitis assessment in AP lumbar radiographs was assessed using intraclass correlation coefficients (ICCs), absolute agreement and κ statistics., Results: A total of 226 sets of radiographs were scored from 113 patients included in the study. The ICC for the sacroiliitis sum score was 0.91 at both baseline and year 2. A total of 62 (54.9%) and 55 (48.7%) patients were classified as r-axSpA at baseline and 65 (57.5%) and 60 (53.1%) patients at year 2 based on evaluation of pelvic and AP lumbar radiographs, respectively. The absolute agreement between the methods on the classification was 84.9 and 85.0% at baseline and year 2, respectively, with the κ of 0.70 at both time points., Conclusion: Radiographic sacroiliitis can be assessed in AP lumbar radiographs with a similar reliability to conventional pelvic radiographs., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: The Assessment of SpondyloArthritis international Society (ASAS) MRI working group conducted a multireader exercise on MRI scans from the ASAS classification cohort to assess the spectrum and evolution of lesions in the sacroiliac joint and impact of discrepancies with local readers on numbers of patients classified as axial spondyloarthritis (axSpA)., Methods: Seven readers assessed baseline scans from 278 cases and 8 readers assessed baseline and follow-up scans from 107 cases. Agreement for detection of MRI lesions between central and local readers was assessed descriptively and by the kappa statistic. We calculated the number of patients classified as axSpA by the ASAS criteria after replacing local detection of active lesions by central readers and replacing local reader radiographic sacroiliitis by central reader structural lesions on MRI., Results: Structural lesions, especially erosions, were as frequent as active lesions (≈40%), the majority of patients having both types of lesions. The ASAS definitions for active MRI lesion typical of axSpA and erosion were comparatively discriminatory between axSpA and non-axSpA. Local reader overcall for active MRI lesions was about 30% but this had a minor impact on the number of patients (6.4%) classified as axSpA. Substitution of radiography with MRI structural lesions also had little impact on classification status (1.4%)., Conclusion: Despite substantial discrepancy between central and local readers in interpretation of both types of MRI lesion, this had a minor impact on the numbers of patients classified as axSpA supporting the robustness of the ASAS criteria for differences in assessment of imaging., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Patients with spondyloarthritis with radiographic sacroiliitis are traditionally classified according to the modified New York (mNY) criteria as ankylosing spondylitis (AS) and more recently according to the Assessment of SpondyloArthritis international Society (ASAS) criteria as radiographic axial spondyloarthritis (r-axSpA)., Objective: To investigate the agreement between the mNY criteria for AS and the ASAS criteria for r-axSpA and reasons for disagreement., Methods: Patients with back pain ≥3 months diagnosed as axSpA with radiographic sacroiliitis (mNY radiographic criterion) were selected from eight cohorts (ASAS, Esperanza, GESPIC, OASIS, Reuma.pt, SCQM, SPACE, UCSF). Subsequently, we calculated the percentage of patients who fulfilled the ASAS r-axSpA criteria within the group of patients who fulfilled the mNY criteria and vice versa in six cohorts with complete information., Results: Of the 3882 patients fulfilling the mNY criteria, 93% also fulfilled the ASAS r-axSpA criteria. Inversely, of the 3434 patients fulfilling the ASAS r-axSpA criteria, 96% also fulfilled the mNY criteria. The main cause for discrepancy between the two criteria sets was the reported age at onset of back pain., Conclusion: Almost all patients with axSpA with radiographic sacroiliitis fulfil both ASAS and mNY criteria, which supports the interchangeable use of the terms AS and r-axSpA., Competing Interests: Competing interests: AM reports grants and speaker/consultancy fees from AbbVie, Pfizer, BMS, UCB and Merck, outside the submitted work; DvdH reports speaker/consultancy fees from AbbVie, Amgen, Astellas, AstraZeneca, BMS, Boehringer Ingelheim, Celgene, Daiichi, Eli-Lilly, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi, Takeda and UCB outside the submitted work and is the Director of Imaging Rheumatology bv.; EDM reports grants and speaker/consultancy fees from AbbVie, BMS, MSD, Novartis, Pfizer, Roche and UCB outside the submitted work; DP reports grants and speaker/consultancy fees from AbbVie, MSD, Novartis and Pfizer and speaker/consultancy fees from BMS, Lilly, Roche, UCB and Celgene outside the submitted work; MR reports speaker/consultancy fees from AbbVie, BMS, Celgene, Chugai, Eli-Lily, Janssen, MSD, Novartis, Pfizer and UCB outside the submitted work; AvT reports grants from Pfizer, AbbVie, UCB and Biogen and grants and speaker/consultancy fees from Novartis outside the submitted work; FAvG reports grants from MSD, Novartis, AbbVie, the Dutch Arthritis Society, Stichting Vrienden van Sole Mio, UCB and Pfizer outside the submitted work; SR reports speaker/consultancy fees from AbbVie, Eli-Lilly, Novartis and Sanofi and grants and speaker/consultancy fees from MSD outside the submitted work. AB, AC, MD, LG and MJS have nothing to disclose. GESPIC has been financially supported by the German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung—BMBF), as part of the German competence network in rheumatology (Kompetenznetz Rheuma). As funding by BMBF was reduced according to schedule in 2005 and stopped in 2007, complementary financial support has been obtained also from Abbott/Abbvie, Amgen, Centocor, Schering-Plough and Wyeth. Since 2010 GESPIC is supported by Abbvie, additional support has been obtained also from ArthroMark (grants number FKZ 01EC1401A) and METARTHROS (grant number FKZ 01EC1407A) projects funded by BMBF., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: To evaluate radiographic progression in the sacroiliac (SI) joints and to identify its predictors during long-term treatment (up to 6 years) with the tumor necrosis factor (TNF) inhibitor etanercept in patients with early axial spondyloarthritis (SpA)., Methods: Patients with early axial SpA who were treated with etanercept for up to 6 years in the Etanercept versus Sulfasalazine in Early Axial Spondyloarthritis (ESTHER) trial were selected based on the availability of radiographs of the SI joints. Two readers who were blinded with regard to clinical data scored the radiographs according to the modified New York criteria (range 0-4 per SI joint). A sacroiliitis sum score (total range 0-8) was calculated as the mean of the scores of the 2 readers. Active and chronic inflammatory changes in the SI joints on magnetic resonance imaging (MRI) performed at baseline, year 2, and year 4 were assessed according to the Berlin MRI scoring system., Results: Of the 76 patients originally included in the study, 42 had radiographs of the SI joints available at baseline and at least 1 follow-up time point (year 2, 4, or 6). The mean ± SD change in the sacroiliitis sum score was 0.13 ± 0.73, -0.27 ± 0.76, and -0.09 ± 0.68, in the time intervals baseline to year 2, year 2 to year 4, and year 4 to year 6, respectively. In the longitudinal mixed model analysis, elevated C-reactive protein level (β = 0.58 [95% confidence interval 0.24, 0.91]) and MRI SI joint osteitis score (β = 0.06 [95% confidence interval 0.03, 0.10]) were independently associated with progression of the sacroiliitis sum score., Conclusion: Our findings indicate that long-term anti-TNF therapy decelerates the progression of structural damage in the SI joints. Elevated CRP level and presence of osteitis on MRI were independently associated with radiographic sacroiliitis progression., (© 2019, American College of Rheumatology.)

Objective: To compare proton density-weighted short-tau inversion recovery (PD-STIR) and T2-weighted fat-suppressed turbo spin echo (T2-FS) sequences for detecting osteitis lesions of the sacroiliac joints (SIJ) in patients with chronic low back pain (CLBP)., Methods: This prospective study included 110 patients with CLBP and suspected spondyloarthritis and 18 healthy controls. All 128 participants (age range: 19-57 yrs) underwent 3.0 Tesla magnetic resonance imaging (MRI) of the SIJ including PD-STIR and T2-FS. Two readers independently scored PD-STIR and T2-FS images for osteitis in separate sessions. Sum scores and signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated. Images were further analyzed as to whether they fulfilled the Assessment of SpondyloArthritis international Society (ASAS) criterion of a positive MRI (MRI+). Interreader agreement was calculated using intraclass correlation coefficients., Results: Average osteitis sum scores were higher for T2-FS images (mean sum score of 4.10 in T2-FS vs 2.55 in PD-STIR, p = 0.017). Mean SNR was 16.54 for PD-STIR and 37.30 for T2-FS (p = 0.0289). Mean CNR was 4.14 for PD-STIR and 20.20 for T2-FS (p = 0.0212). For both readers, the ASAS MRI+ definition was more often fulfilled by T2-FS than by PD-STIR images, resulting in more patients being classified as having axial spondyloarthritis (axSpA): 68 patients using T2-FS versus 58 patients using PD-STIR. Interreader intraclass correlation coefficients were very good for both PD-STIR (0.91) and T2-FS (0.86)., Conclusion: T2-FS sequences improve image quality and hence the detection of osteitis compared to the PD-STIR sequence. More patients were classified as axSpA based on a positive MRI by T2-FS.

Objective: Radiographs of sacroiliac (SI) joints are used for the detection of structural damage in patients with axial spondyloarthritis (axSpA), but are often difficult to interpret. Here, we address the question how the T1-weighted MRI (T1w MRI) sequence compares with radiography for SI joints' structural lesions using low-dose CT as the standard of reference., Methods: Radiographs, T1w MRI and low-dose CT of the SI joints from 110 patients (mean age 36.1 (19-57) years, 52% males and 48% females; 53% with axSpA, 21 non-radiographic axSpA and 32% radiographic axSpA, 47% with non-SpA) referred to the rheumatologist because of unclear chronic back pain, but possible axSpA, were scored for structural lesions (erosions, sclerosis, joint space changes and an overall impression of positivity)., Results: Using low-dose CT as the standard of reference, T1w MRI showed markedly better sensitivity with significantly more correct imaging findings compared with radiography for erosions (79% vs 42%; p=0.002), joint space changes (75% vs 41%; p=0.002) and overall positivity (85% vs 48%; p=0.001), respectively, while there were no differences between X-rays and MRI-T1 sequence regarding specificity (>80% for all scores). Only for sclerosis, MRI-T1 was inferior to radiography (sensitivity 30% vs 70%, respectively), however, not statistically significant (p=0.663)., Conclusions: T1w MRI was superior to radiography in the detection of structural lesion of the SI joints in patients with axSpA. Future studies should focus on finding an agreement on the definition of MRI-T1 positivity., Competing Interests: Competing interests: None declared., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Objectives: To review and update the existing definition of a positive MRI for classification of axial spondyloarthritis (SpA)., Methods: The Assessment in SpondyloArthritis International Society (ASAS) MRI working group conducted a consensus exercise to review the definition of a positive MRI for inclusion in the ASAS classification criteria of axial SpA. Existing definitions and new data relevant to the MRI diagnosis and classification of sacroiliitis and spondylitis in axial SpA, published since the ASAS definition first appeared in print in 2009, were reviewed and discussed. The precise wording of the existing definition was examined in detail and the data and a draft proposal were presented to and voted on by the ASAS membership., Results: The clear presence of bone marrow oedema on MRI in subchondral bone is still considered to be the defining observation that determines the presence of active sacroiliitis. Structural damage lesions seen on MRI may contribute to a decision by the observer that inflammatory lesions are genuinely due to SpA but are not required to meet the definition. The existing definition was clarified adding guidelines and images to assist in the application of the definition., Conclusion: The definition of a positive MRI for classification of axial SpA should continue to primarily depend on the imaging features of 'active sacroiliitis' until more data are available regarding MRI features of structural damage in the sacroiliac joint and MRI features in the spine and their utility when used for classification purposes., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Purpose of Review: The concept of axial spondyloarthritis with two forms or subtypes (nonradiographic and radiographic) has been established over the last few years. However, debates concerning especially the nonradiographic form of the disease are still ongoing. Here we summarise recent data on similarities and differences (and their possible explanations) between nonradiographic axial spondyloarthritis and radiographic axial spondyloarthritis (ankylosing spondylitis)., Recent Findings: Nonradiographic and radiographic forms are about equally frequent among patients first diagnosed with axial spondyloarthritis and have in general similar clinical characteristics, especially related to clinical signs of disease activity and similar rates of treatment response. Nonradiographic axial spondyloarthritis is characterised by a higher prevalence of females and lower percentage of patients with elevated C-reactive protein that might reflect the presence of a certain proportion of patients who develop structural damage in the axial skeleton very slowly or do not develop it at all. Elevated C-reactive protein and active sacroiliitis on magnetic resonance imaging are strongest predictors of structural damage development in the sacroiliac joints and, therefore, of progression from nonradiographic to radiographic stage. The same parameters predict a good clinical response to therapy with tumour necrosis factor alpha blocking agent in axial spondyloarthritis, but especially if used in nonradiographic disease., Summary: Currently available data support the concept of axial spondyloarthritis as one entity. Nonradiographic axial spondyloarthritis seems to be, however, more heterogeneous than ankylosing spondylitis because of the presence of patients with a self-limiting disease or a slow disease course.

Objective: We investigated the performance of magnetic resonance imaging (MRI) compared to conventional radiographs for detection of chronic structural changes in the sacroiliac joints (SIJ) in patients with axial spondyloarthritis (SpA)., Methods: We included 112 patients with definite axial SpA (68 with ankylosing spondylitis and 44 with nonradiographic axial SpA), for whom radiographs and MRI scans of the SIJ performed at the same time were available. Radiographs and MRI of the SIJ were scored for subchondral sclerosis (score 0-2), erosions (score 0-3), and joint space changes (score 0-5) in each SIJ. Readers provided an overall impression of the extent of damage according to the scoring system of the modified New York criteria., Results: In total, 224 SIJ from 112 patients were available for analysis. There was rather low agreement between MRI and radiographs concerning definite erosions of SIJ (κ = 0.11), moderate agreement for definite subchondral sclerosis (κ = 0.46) and definite joint space abnormalities (κ = 0.41), and almost perfect agreement for joint ankylosis (κ = 0.85). MRI demonstrated a good overall performance in detection of definite "chronic" sacroiliitis, with a sensitivity of 84% and a specificity of 61%. For sacroiliitis fulfilling the modified New York criteria, MRI had a sensitivity of 81% and a specificity of 64% using radiographs as the reference method., Conclusion: MRI demonstrated good overall performance for detection of chronic structural changes in the SIJ as compared to radiographs.

Objective: To assess the progression of radiographic sacroiliitis in a cohort of patients with early axial spondyloarthritis over a period of 2 years and to explore predictors of progression., Methods: 210 patients with axial spondyloarthritis from the German Spondyloarthritis Inception Cohort have been selected for this analysis based on availability of radiographs at baseline and after 2 years of follow-up. Radiographs were centrally digitised and the sacroiliac joints were scored independently according to the grading system of the modified New York criteria for ankylosing spondylitis (AS) by two trained readers. The readers scored both time points simultaneously but were blinded for the time point and for all clinical data., Results: 115 patients (54.8%) fulfilled the modified New York criteria for AS in their radiographic part in the opinion of both readers at baseline, while 95 patients (45.2%) were classified as non-radiographic axial spondyloarthritis. More patients with non-radiographic spondyloarthritis (10.5%) compared with AS (4.4%) showed an estimated 'true' progression by at least one grade according to both readers, although the difference between the two groups was statistically non-significant. The rate of progression from non-radiographic axial spondyloarthritis to AS was 11.6% over 2 years. An elevated level of C-reactive protein (CRP) at baseline was a strong positive predictor of radiographic sacroiliitis progression in non-radiographic axial spondyloarthritis and AS (OR 3.65 and 5.08, respectively, p<0.05)., Conclusion: Progression of radiographic sacroiliitis by at least one grade after 2 years occurs only in a small percentage of patients with early axial spondyloarthritis. An elevated level of CRP was found to be a strong positive predictor of sacroiliitis progression.