J Brandt

The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis (part II): validation and final selection

Objective: To validate and refine two sets of candidate criteria for the classification/diagnosis of axial spondyloarthritis (SpA). Methods: All Assessment of SpondyloArthritis international Society (ASAS) members were invited to include consecutively new patients with chronic (⩾3 months) back pain of unknown origin that began before 45 years of age. The candidate criteria were first tested in the entire cohort of 649 patients from 25 centres, and then refined in a random selection of 40% of cases and thereafter validated in the remaining 60%. Results: Upon diagnostic work-up, axial SpA was diagnosed in 60.2% of the cohort. Of these, 70% did not fulfil modified New York criteria and, therefore, were classified as having “non-radiographic” axial SpA. Refinement of the candidate criteria resulted in new ASAS classification criteria that are defined as: the presence of sacroiliitis by radiography or by magnetic resonance imaging (MRI) plus at least one SpA feature (“imaging arm”) or the presence of HLA-B27 plus at least two SpA features (“clinical arm”). The sensitivity and specificity of the entire set of the new criteria were 82.9% and 84.4%, and for the imaging arm alone 66.2% and 97.3%, respectively. The specificity of the new criteria was much better than that of the European Spondylarthropathy Study Group criteria modified for MRI (sensitivity 85.1%, specificity 65.1%) and slightly better than that of the modified Amor criteria (sensitivity 82.9, specificity 77.5%). Conclusion: The new ASAS classification criteria for axial SpA can reliably classify patients for clinical studies and may help rheumatologists in clinical practice in diagnosing axial SpA in those with chronic back pain. Trial registration number: NCT00328068.

The Assessment of SpondyloArthritis international Society classification criteria for peripheral spondyloarthritis and for spondyloarthritis in general

Objective To evaluate new classification criteria for peripheral spondyloarthritis (SpA) in patients with SpA with peripheral manifestations only. Methods In this Assessment of SpondyloArthritis international Society (ASAS) study, two prespecified sets of criteria were compared against the European Spondylarthropathy Study Group (ESSG) and Amor criteria in newly referred consecutive patients with undiagnosed peripheral arthritis, and/or enthesitis, and/or dactylitis that usually began before 45 years of age. The clinical diagnosis (SpA vs no SpA) made by the ASAS rheumatologist served as reference standard. Results In all, 24 ASAS centres included 266 patients, with a final diagnosis of SpA being made in 66.2%. After adjustments a final set of criteria showed the best balance between sensitivity (77.8%) and specificity (82.9%): arthritis and/or enthesitis and/or dactylitis plus (A) one or more of the following parameters: psoriasis, inflammatory bowel disease, preceding infection, human leucocyte antigen B27, uveitis, sacroiliitis on imaging, or (B) two or more other parameters: arthritis, enthesitis, dactylitis, inflammatory back pain in the past, family history of SpA. The new criteria performed better than modified versions of the ESSG (sensitivity 62.5%, specificity 81.1%) and the Amor criteria (sensitivity 39.8%, specificity 97.8%), particularly regarding sensitivity. In the entire ASAS population of 975 patients the combined use of ASAS criteria for axial SpA and ASAS criteria for peripheral SpA also had a better balance (sensitivity 79.5%, specificity 83.3%) than the modified ESSG (sensitivity 79.1%, specificity 68.8%) and Amor criteria (sensitivity 67.5%, specificity 86.7%), respectively. Conclusions The new ASAS classification criteria for peripheral SpA performed well in patients presenting with peripheral arthritis, enthesitis and/or dactylitis.

The Assessment of SpondyloArthritis international Society (ASAS) handbook: a guide to assess spondyloarthritis

The field of spondyloarthritis (SpA) has experienced major progress in the last decade, especially with regard to new treatments, earlier diagnosis, imaging technology and a better definition of outcome parameters for clinical trials. In the present work, the Assessment in SpondyloArthritis international Society (ASAS) provides a comprehensive handbook on the most relevant aspects for the assessments of spondyloarthritis, covering classification criteria, MRI and x rays for sacroiliac joints and the spine, a complete set of all measurements relevant for clinical trials and international recommendations for the management of SpA. The handbook focuses at this time on axial SpA, with ankylosing spondylitis (AS) being the prototype disease, for which recent progress has been faster than in peripheral SpA. The target audience includes rheumatologists, trial methodologists and any doctor and/or medical student interested in SpA. The focus of this handbook is on practicality, with many examples of MRI and x ray images, which will help to standardise not only patient care but also the design of clinical studies.

The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis (part I): classification of paper patients by expert opinion including uncertainty appraisal

Objective: Non-radiographic axial spondyloarthritis (SpA) is characterised by a lack of definitive radiographic sacroiliitis and is considered an early stage of ankylosing spondylitis. The objective of this study was to develop candidate classification criteria for axial SpA that include patients with but also without radiographic sacroiliitis. Methods: Seventy-one patients with possible axial SpA, most of whom were lacking definite radiographic sacroiliitis, were reviewed as “paper patients” by 20 experts from the Assessment of SpondyloArthritis international Society (ASAS). Unequivocally classifiable patients were identified based on the aggregate expert opinion in conjunction with the expert-reported level of certainty of their judgement. Draft criteria for axial SpA were formulated and tested using classifiable patients. Results: Active sacroiliitis on magnetic resonance imaging (MRI) (odds ratio 45, 95% CI 5.3 to 383; p<0.001) was strongly associated with the classification of axial SpA. The knowledge of MRI findings led to a change in the classification of 21.1% of patients. According to the first set of candidate criteria (sensitivity 97.1%; specificity 94.7%) a patient with chronic back pain is classified as axial SpA in the presence of sacroiliitis by MRI or x rays in conjunction with one SpA feature or, if sacroilitiis is absent, in the presence of at least three SpA features. In a second set of candidate criteria, inflammatory back pain is obligatory in the clinical arm (sensitivity 86.1%; specificity 94.7%). Conclusion: The ASAS group has developed candidate criteria for the classification of axial SpA that include patients without radiographic sacroiliitis. The candidate criteria need to be validated in an independent international study.

New criteria for inflammatory back pain in patients with chronic back pain: a real patient exercise by experts from the Assessment of SpondyloArthritis international Society (ASAS)

Objective: Inflammatory back pain (IBP) is an important clinical symptom in patients with axial spondyloarthritis (SpA), and relevant for classification and diagnosis. In the present report, a new approach for the development of IBP classification criteria is discussed. Methods: Rheumatologists (n = 13) who are experts in SpA took part in a 2-day international workshop to investigate 20 patients with back pain and possible SpA. Each expert documented the presence/absence of clinical parameters typical for IBP, and judged whether IBP was considered present or absent based on the received information. This expert judgement was used as the dependent variable in a logistic regression analysis in order to identify those individual IBP parameters that contributed best to a diagnosis of IBP. The new set of IBP criteria was validated in a separate cohort of patients (n = 648). Results: Five parameters best explained IBP according to the experts. These were: (1) improvement with exercise (odds ratio (OR) 23.1); (2) pain at night (OR 20.4); (3) insidious onset (OR 12.7); (4) age at onset <40 years (OR 9.9); and (5) no improvement with rest (OR 7.7). If at least four out of these five parameters were fulfilled, the criteria had a sensitivity of 77.0% and specificity of 91.7% in the patients participating in the workshop, and 79.6% and 72.4%, respectively, in the validation cohort. Conclusion: This new approach with real patients defines a set of IBP definition criteria using overall expert judgement on IBP as the gold standard. The IBP experts’ criteria are robust, easy to apply and have good face validity.

Progression of radiographic damage in patients with ankylosing spondylitis - Defining the central role of syndesmophytes

Background: Structural changes such as erosions, syndesmophytes and ankylosis are characteristic of ankylosing spondylitis (AS). These can be quantified by the modified Stokes Anklylosing Spondylitis Spinal Score (mSASSS). It is unknown which radiographic feature is most relevant for the assessment of change and the prediction of future damage in AS. Objectives: To analyse radiographic progression in AS by using different assessments to define the most important changes. Methods: Spinal radiographs of 116 patients with AS were scored by the mSASSS at baseline (BL) and after 2 years. Radiographic progression was assessed by differentiating (1) any change; (2) progression to syndesmophytes/ankylosis (definite change); and (3) changes exceeding the smallest detectable change (SDC) as predefined. A growth angle of 45° was used to differentiate syndesmophytes from spondylophytes. Results: Some radiographic progression after 2 years was detected in 42% of patients, novel syndesmophytes in 31% of patients, and, using the SDC (calculated at 2 mSASSS units) as cut-off, progression was seen in 28% of patients. Thus, in 74% of the patients changes were because of syndesmophytes and/or ankylosis. Using the predefined cut-off, only 12% of all syndesmophytes were spondylophytes. Patients with such changes were of older age. Definite radiographic progression was found in 44% of the patients with syndesmophytes/ankylosis at BL (n = 57) versus 19% (p = 0.03) of the patients without such changes (n = 59). Conclusions: Syndesmophytes and ankylosis are the most relevant structural changes in AS, and also in the mSASSS. Development of just one syndesmophyte within 2 years indicates progression of structural changes in AS; this is relevant for clinical practice. Syndesmophytes are the best predictors of radiographic progression.

Inflammation in ankylosing spondylitis: a systematic description of the extent and frequency of acute spinal changes using magnetic resonance imaging

Background: Magnetic resonance imaging (MRI) is increasingly used to detect inflammation in the spine of patients with ankylosing spondylitis (AS). Objectives: To detect differentially the presence and extent of inflammation in the three spinal segments of patients with AS by MRI. Methods: In 38 patients with active AS, acute spinal lesions were assessed by T1 weighted, gadolinium enhanced, spin echo MRI (T1/Gd-DTPA) and short τ inversion recovery (STIR) sequences. MRI was quantified by the validated scoring system ASspiMRI-a. Acute spinal lesions were detected in the whole spine and in each spinal segment. One vertebral unit (VU) was defined as the region between two virtual lines drawn through the middle of each vertebral body. Results: A greater number of inflammatory spinal lesions were found by the STIR sequence than by Gd-DTPA: inflammation was present in 30.6% of the VUs as assessed by STIR, compared with 26.8% of the same VUs assessed by T1/Gd-DTPA. Inflammation was found more commonly in the thoracic spine (TS) than in the cervical (CS) or the lumbar spine (LS) with both techniques. When STIR was used, spinal inflammation in the CS, the TS, and LS was detected in 10/38 (26%), 28/38 (74%), and 9/38 (24%) patients, respectively. The VU T7/8 was found to be the VU most often affected by both techniques (27.8% by T1/Gd-DTPA and 34.5% by STIR). Conclusions: Spinal inflammation is a common manifestation in patients with AS, and appears more frequently in the TS. The scoring system ASspiMRI-a can be used for evaluation of acute spinal changes in AS.

Up regulation of the production of tumour necrosis factor α and interferon γ by T cells in ankylosing spondylitis during treatment with etanercept

Background: Treatment of active ankylosing spondylitis (AS) with the recombinant, soluble tumour necrosis factor α (TNFα) receptor molecule etanercept has been shown to be clinically highly effective. The precise mechanism of action, however, is not known. Objective: To assess the change in the cytokine secreting ability of CD4+ and CD8+ T cells and macrophages during etanercept treatment. Patients and methods: Peripheral blood mononuclear cells from 10 patients with AS treated with 25 mg etanercept and 10 patients with AS treated with placebo were investigated during treatment given twice weekly subcutaneously. Production of cytokines by T cells was investigated after in vitro stimulation by flow cytometry. Results: Twelve weeks of etanercept treatment induced a significant increase in the number of interferon γ (IFNγ) positive (14.2% (9.6–19.5%) before v 24.4% (13.4–36.4%) after) and TNFα positive CD4+ T cells (p=0.008 for both cytokines) and IFNγ positive (37.5% (19.0–45.4%) before v 52.9% (33.2–60.0%) after) and TNFα positive CD8+ T cells (p=0.008 for both cytokines) upon phorbol myristate acetate/ionomycin stimulation, but not in the placebo group. Furthermore, etanercept treatment induced a significant increase in the number of IFNγ positive CD8+ T cells (p=0.024 at 12 weeks) and a non-significant increase of TNFα positive CD8+ T cells after in vitro stimulation with the aggrecan derived peptides. Conclusions: Neutralisation of peripheral TNFα does not induce a down regulation of the ability of T cells to produce TNFα but rather an up regulation, possibly due to a counterregulatory mechanism.

Which spinal lesions are associated with new bone formation in patients with ankylosing spondylitis treated with anti-TNF agents? A long-term observational study using MRI and conventional radiography

Objective To study the relationship of spinal inflammation and fatty degeneration (FD) as detected by MRI and new bone formation seen on conventional radiographs (CRs) in ankylosing spondylitis (AS). Methods CRs at baseline, 2 years and 5 years and spinal MRIs at baseline and 2 years of 73 AS patients treated with infliximab in European AS Infliximab Cohort were available. Relative risks (RR) were calculated with a general linear model after adjustment for within-patient variation. Results In a total of 1466 vertebral edges (VEs) without baseline syndesmophytes, 61 syndesmophytes developed at 5 years, the majority of which (57.4%) had no corresponding detectable MRI lesions at baseline. VEs with both inflammation and FD at baseline had the highest risk (RR 3.3, p=0.009) for syndesmophyte formation at 5 years, followed by VEs that developed new FD or did not resolve FD at 2 years (RR=2.3, p=0.034), while inflammation at baseline with no FD at 2 years had the lowest risk for syndesmophyte formation at 5 years (RR=0.8). Of the VEs with inflammation at baseline, >70% resolved completely, 28.8% turned into FD after 2 years, but only 1 syndesmophyte developed within 5 years. Conclusions Parallel occurrence of inflammation and FD at baseline and development of FD without prior inflammation after 2 years were significantly associated with syndesmophyte formation after 5 years of anti-tumour necrosis factor (TNF) therapy. However, the sequence ‘inflammation–FD–new bone formation’ was rarely observed, an argument against the TNF-brake hypothesis. Whether an early suppression of inflammation leads to a decrease of the risk for new bone formation remains to be demonstrated.

Markov model into the cost-utility over five years of etanercept and infliximab compared with usual care in patients with active ankylosing spondylitis

Objective: To estimate the incremental cost-utility of etanercept and infliximab compared with usual care in active ankylosing spondylitis. Methods: A Markov model over five years with cycle times of three months was computed. Patients included all had active disease, defined as Bath ankylosing spondylitis disease activity index (BASDAI) ⩾4 and could reach low disease activity, defined as BASDAI <4. Non-response to tumour necrosis factor α (TNFα) inhibitors was always followed by cessation of treatment. Response to TNFα inhibitors could be followed at any time by either relapse to BASDAI ⩾4, leading to cessation of treatment, or toxicity, leading to cessation of treatment if major. Probabilities for efficacy, relapse, and toxicity were derived from two European randomised controlled trials. Utilities and costs assigned to the BASDAI disease states were derived from a two year observational Dutch cohort. In sensitivity analyses probabilities of effectiveness, toxicity, costs, and utilities were varied. Results: Over five years the total quality adjusted life years varied from 2.57 to 2.89 for usual care, compared with 3.13 to 3.42 and 3.07 to 3.35 for etanercept or infliximab. Cumulative costs were between €49 555 to 69 982 for usual care compared with €59 574 to 91 183 or €28 3330 to 106 775 for etanercept and infliximab. This resulted in incremental cost-utility ratios varying between €42 914 and 123 761 per QALY for etanercept compared with usual care and €67 207 to 237 010 for infliximab. The model was sensitive to drug prices. Conclusion: Etanercept and infliximab have large clinical effects in ankylosing spondylitis. The present model suggests the high drug costs restricts efficient use in all patients who have a BASDAI >4. The validity of the model is limited by insufficient insight in the natural course of the disease and long term effectiveness and toxicity of TNFα inhibitors.