Background The transition from psoriasis (PsO) to psoriatic arthritis (PsA) and the early diagnosis of PsA is of considerable scientific and clinical interest for the prevention and interception of PsA. Objective To formulate EULAR points to consider (PtC) for the development of data-driven guidance and consensus for clinical trials and clinical practice in the field of prevention or interception of PsA and for clinical management of people with PsO at risk for PsA development. Methods A multidisciplinary EULAR task force of 30 members from 13 European countries was established, and the EULAR standardised operating procedures for development for PtC were followed. Two systematic literature reviews were conducted to support the task force in formulating the PtC. Furthermore, the task force proposed nomenclature for the stages before PsA, through a nominal group process to be used in clinical trials. Results Nomenclature for the stages preceding PsA onset, 5 overarching principles and 10 PtC were formulated. Nomenclature was proposed for three stages towards PsA development, namely people with PsO at higher risk of PsA, subclinical PsA and clinical PsA. The latter stage was defined as PsO and associated synovitis and it could be used as an outcome measure for clinical trials evaluating the transition from PsO to PsA. The overarching principles address the nature of PsA at its onset and underline the importance of collaboration of rheumatologists and dermatologists for strategies for prevention/interception of PsA. The 10 PtC highlight arthralgia and imaging abnormalities as key elements of subclinical PsA that can be used as potential short-term predictors of PsA development and useful items to design clinical trials for PsA interception. Traditional risk factors for PsA development (ie, PsO severity, obesity and nail involvement) may represent more long-term disease predictors and be less robust for short-term trials concerning the transition from PsO to PsA. Conclusion These PtC are helpful to define the clinical and imaging features of people with PsO suspicious to progress to PsA. This information will be helpful for identification of those who could benefit from a therapeutic intervention to attenuate, delay or prevent PsA development.

Objective The aim of this work was to investigate the association between disease activity measured by the Ankylosing Spondylitis Disease Activity Score (ASDAS) and radiographic spinal progression in patients with early axial spondyloarthritis (axSpA). Methods Altogether, 178 patients with definite axSpA (100 with ankylosing spondylitis and 78 with non-radiographic axSpA) were included. Spinal radiographs (baseline and year 2) were assessed according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) and for the presence of syndesmophytes. Clinical and lab data were collected at baseline and every 6 months thereafter. Time-averaged (over 2 years) values of the C-reactive protein based ASDAS were calculated. Results There was a clear positive association between disease activity according to ASDAS and radiographic spinal progression. In the logistic regression analysis, mSASSS progression by ≥2 points over 2 years was significantly associated with the time-averaged ASDAS: unadjusted OR=1.64 (95% CI 1.03 to 2.62), adjusted (for presence of syndesmophytes at baseline, smoking status and intake of non-steroidal anti-inflammatory drugs) OR=1.80 (95% CI 1.04 to 3.13). Syndesmophyte formation/progression demonstrated an even stronger association with the time-averaged ASDAS: unadjusted OR=2.62 (95% CI 1.46 to 4.68), adjusted OR=2.45 (95% CI 1.26 to 4.77). Conclusions Persisting high disease activity according to the ASDAS is associated with accelerated radiographic spinal progression in early axSpA.

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.

Objectives To define the instruments for the Assessment of SpondyloArthritis international Society–Outcomes Measures in Rheumatology (ASAS-OMERACT) core domain set for axial spondyloarthritis (axSpA). Methods An international working group representing key stakeholders selected the core outcome instruments following a predefined process: (1) identifying candidate instruments using a systematic literature review; (2) reducing the list of candidate instruments by the working group, (3) assessing the instruments’ psychometric properties following OMERACT filter 2.2, (4) selection of the core instruments by the working group and (5) voting and endorsement by ASAS. Results The updated core set for axSpA includes seven instruments for the domains that are mandatory for all trials: Ankylosing Spondylitis Disease Activity Score and Numerical Rate Scale (NRS) patient global assessment of disease activity, NRS total back pain, average NRS of duration and severity of morning stiffness, NRS fatigue, Bath Ankylosing Spondylitis Function Index and ASAS Health Index. There are 9 additional instruments considered mandatory for disease-modifying antirheumatic drugs (DMARDs) trials: MRI activity Spondyloarthritis Research Consortium of Canada (SPARCC) sacroiliac joints and SPARCC spine, uveitis, inflammatory bowel disease and psoriasis assessed as recommended by ASAS, 44 swollen joint count, Maastricht Ankylosing Spondylitis Enthesitis Score, dactylitis count and modified Stoke Ankylosing Spondylitis Spinal Score. The imaging outcomes are considered mandatory to be included in at least one trial for a drug tested for properties of DMARD. Furthermore, 11 additional instruments were also endorsed by ASAS, which can be used in axSpA trials on top of the core instruments. Conclusions The selection of the instruments for the ASAS-OMERACT core domain set completes the update of the core outcome set for axSpA, which should be used in all trials.

Objectives: Osteitis condensans ilii (OCI) has become an important differential diagnosis for axial spondyloarthritis (axSpA). The objective of this matched case–control study was to investigate demographic, clinical, laboratory and MRI characteristics of OCI as compared with axial spondyloarthritis (axSpA). Methods: A total of 60 patients diagnosed with OCI were included in the final analysis. From 27 of these patients, MRIs of the sacroiliac joints were available. OCI patients were matched with a 1:1 ratio by back pain duration to patients with definite axSpA in order to compare clinical, laboratory and MRI characteristics. Results: The OCI patients were nearly all females (96.7 vs 46.7%), had a significantly lower prevalence of inflammatory back pain (39.5 vs 88.9%), a significantly lower percentage of HLA-B27 positives (35.2 vs 80.0%) and a lower prevalence of the majority of other SpA features as compared with axSpA patients. Interestingly, there was no difference in the prevalence of osteitis in the sacroiliac joints (92.6 vs 85.2% in OCI and axSpA, respectively, P = 0.44), but there was a difference in the prevalence of erosions (7.4 vs 66.7%, respectively, P = 0.0001). In addition, in OCI nearly all lesions were localized in the anterior part of the sacroiliac joints while in axSpA lesions were localized predominantly in the middle part of the joint (for osteitis: 96 vs 4% in OCI and 28.6 vs 71.4% in axSpA; P = 0.0002 for the inter-group difference). Conclusion: Clinical and imaging features of OCI compared with axSpA are described that should help in differential diagnosis.

Introduction: Non-radiographic axial spondyloarthritis (nr-axSpA) represents a subtype of axial spondyloarthritis (axSpA) with no significant structural damage in sacroiliac joints and spine. In addition, patients with nr-axSpA demonstrate a substantial burden of illness, and a considerable share of them might progress to radiographic axSpA (r-axSpA) over time. The amount and quality of published data allows crude estimation of progression rate and factors related to a higher risk of progression. Areas covered: This review discusses the available data reporting the rates and predictors of radiographic progression in the sacroiliac joints and in the spine in patients with nr-axSpA as well as predisposing factors for such a progression. Expert commentary: Most of the studies report about 10–40% of patients with nr-axSpA to progress to r-axSpA over a period of 2–10 years. Multiple risk factors for the radiographic sacroiliitis progression are outlined and explored. There are not enough data to presume that any treatment modality may influence progression from nr-axSpA to r-axSpA, with TNFi showing some promising results. Radiographic progression in the spine is in general low in nr-axSpA; thus, long-term studies are required to investigate the natural course of the progression and possible treatment effects.