M. de Hooge

FRI0245 How Reliable is the Scoring of Msasss in Clinical Practice in Centers Participating in Desir? Comparison with the Gold Standard Central Reading

Background Spinal X-rays are considered as gold standard for assessing structural damage in the spine in AS, and a scoring system, the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) is the preferred assessment method. In clinical studies and therapeutic trials, the mSASSS scoring process is usually done by ≥1 trained readers. In daily practice, the ability of rheumatologists and radiologists to adequately use the mSASSS without a specific training is unknown. In addition, it is not known what the impact would be in studies when using the score of multiple readers in various centres as in daily practice, instead of using a centralized scoring with a few trained readers Objectives To compare the results of the mSASSS of the local reading of baseline spinal X-rays to the centralized reading as the gold standard Methods Patients aged 18-50 with recent chronic back pain (≥3 months, ≤3 years) from 25 participating centers in France were included in the DESIR (Devenir des Spondylarthropathies Indifferenciées Récentes) -cohort (n=708). All available baseline X-rays of cervical and lumbar spine were scored by the local radiologist/rheumatologist who might have access to clinical data, according to the mSASSS scoring method. In addition, 2 well-calibrated centralized readers independently scored the same X-rays, blinded for any other data. In case the centralized readers disagreed, an experienced radiologist served as adjudicator. Agreement between the 2 centralized readers, and between the local and centralized scores was calculated (Kappa; percentage agreement). To calculate the agreement between readers a cut-off of ≥1 for mSASSS was used. When comparing centralized readers with local readers the mSASSS of the centralized readers was combined Results Patients with complete X- ray data (n=664) were included in these analyses. The large majority of patients had a normal mSASSS both scored by the central and local readers. The agreement between the 2 centralized readers was 89.3% with a kappa of 0.50 (see Table 1). Comparing the local readings with the centralized scores there was an agreement in 72.2% of the cases with a kappa of 0.19. The local readers scored an mSASSS ≥1 in 169 cases, while this was in 119 cases if scored by central readers Table 1 Reader 2 Reader 1 mSASSS ≥1 mSASSS <1 mSASSS ≥1 45 29 mSASSS <1 42 548 Kappa = 0.50/Agreement = 89.3% Centralized score (2/3) Local score mSASSS ≥1 mSASSS <1 mSASSS ≥1 52 117 mSASSS <1 67 427 Kappa = 0.19/Agreement = 72.2% Conclusions The agreement between two trained central readers is better than between central and local readers. Local readers overestimate damage in the spine in comparison to the gold standard of central reading Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.1522

OP0189 Tumor necrosis factor inhibitor treatment reduces spinal radiographic progression in ankylosing spondylitis by decreasing disease activity: a longitudinal analysis in a large prospective cohort

Background Whether tumor necrosis factor inhibitors (TNFi) have an influence on radiographic progression in ankylosing spondylitis (AS) remains controversial. Objectives To investigate the impact of TNFi use on spinal radiographic progression in AS. Methods Patients fulfilling the modified NY Criteria for AS (as assessed by central reading) in the Swiss Clinical Quality Management Cohort with at least 2 years of clinical and radiographic follow-up were included. Spinal X-rays were taken every 2 years and scored independently by 2 blinded readers according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) in chronological time order. Average score of the readers was used. Radiographic progression was defined as an increase by ≥2 mSASSS units over 2 years. The relationship between TNFi use before a 2 year X-ray interval and progression within the interval was investigated using binomial generalized estimating equation models with adjustment for potential confounding and multiple imputation of missing covariate data. Ankylosing Spondylitis Disease Activity Score (ASDAS) was regarded as a potential intermediate variable mediating the effect of TNFi on radiographic progression. It was added to the model as a time-varying variable in a sensitivity analysis. Results A total of 420 patients with AS contributed to data for 597 x-ray intervals in adjusted analyses (1–5 intervals per patient); BL characteristics: male sex 66%, HLA-B27 81%, mean (SD) age 40.4 (10.9) years, disease duration 13.9 (9.8) years, mSASSS 6.4 (12.4), ASDAS 2.8 (1.1)). 39% of the patients were already on TNFi at first X-ray. Mean mSASSS progression in 2 years was 0.9 (2.7) units. The multivariable model (Table) shows that prior use of TNFi reduced the odds of progression in the next 2 year interval by 49% (odds ratio (OR) 0.51, 95% confidence interval (CI) 0.28–0.92, p=0.03). BL mSASSS and male sex also significantly affected progression. Adding ASDAS as a covariate to the model decreased the estimated effect of TNFi on progression: OR 0.65, 95% CI 0.36–1.17, p=0.15. In this model, a decrease in ASDAS by 1 unit would lower the odds for progression by 0.62 (p=0.001).Table 1. Longitudinal multivariable analysis of radiographic progression Variable OR 95% CI P value TNFi use prior to X-ray interval 0.51 0.28–0.92 0.03 NSAID use at start X-ray interval 0.81 0.40–1.63 0.55 mSASSS at start X-ray interval 1.06 1.04–1.07 <0.001 Male gender 3.01 1.56–5.77 0.001 Disease duration 1.01 0.99–1.04 0.38 Current smoking 0.94 0.55–1.61 0.83 HLA-B27 0.99 0.46–2.12 0.98 Nb of exercise sessions per week 0.93 0.80–1.08 0.35 Peripheral arthritis 1.00 0.56–1.79 1.00 Conclusions TNFi seem to reduce radiographic progression in patients with AS and this effect is mediated, at least in part, by a decrease in disease activity. Acknowledgements Supported by the Stiftung für Rheumaforschung and a research grant from the investigator initiated studies program of MSD. Disclosure of Interest C. Molnar: None declared, A. Scherer: None declared, X. Baraliakos: None declared, M. de Hooge: None declared, R. Micheroli: None declared, P. Exer: None declared, R. Kissling: None declared, G. Tamborrini: None declared, L. Wildi: None declared, M. Nissen: None declared, P. Zufferey: None declared, J. Bernhard Consultant for: Merck Sharp & Dohme, Pfizer, Roche, U. Weber Consultant for: Abbvie, R. Landewé: None declared, D. van der Heijde: None declared, A. Ciurea Consultant for: Abbvie, Celgene, Eli Lilly, Janssen-Cilag, Merck Sharp & Dohme, Novartis, Pfizer, UCB

AB1096 Local Radiologists Score More Abnormalities in Comparison to Central Readers Leading to More Patients Fulfilling the Classification Criteria of Axial Spa: Data from the Space-Cohort

Background The interpretation of findings on MRI and radiographs of the sacroiliac joints (MRI-SI and X-SI respectively) is known to vary amongst radiologists and trained readers as recently shown in the DESIR-cohort in France1. Since imaging is used in the ASAS axial spondyloarthritis (axSpA) criteria for the classification of patients, different findings can result in a different SpA classification. Objectives To objectify if classification (ASAS axSpA criteria) of patients (pts) in the SPACE-cohort differed based on evaluation of MRI-SI and X-SI by radiologists (local evaluation) and two blinded readers (central reading). Methods The SpondyloArthritis Caught Early (SPACE)-cohort includes pts with chronic back pain (≥3 months, ≤2 years, onset <45 years) visiting the rheumatology outpatient clinics of five participating centres in the Netherlands, Norway and Italy. Local radiologists provided information on bone marrow oedema compatible with sacroiliitis and signs of radiographic sacroiliitis compatible with axSpA without formal scoring. MRI-SI were scored by the central readers according to the ASAS definition and X-SI were scored according to the mNY criteria. In case of disagreement, an experienced reader served as adjudicator. MRI-SI and X-SI were considered positive if 2/3 readers agreed. Pts were classified according to the ASAS axSpA criteria using the scores of local evaluation and again using the scores of central reading. Results In total, 143/395 pts (36.2%) fulfilled the ASAS axSpA criteria based on central reading and 170/395 pts (43,0%) based on local evaluation. MRI-SI was rated discordant in 34 pts (8.4%) and concordant in 27 pts (6.8%); these figures were 19 pts (4.8%) and 12 pts (3.0%) for X-SI. In 43 pts (10.9%) a different reading resulted in a different rating of presence of axSpA; 35 pts (8.9%) classified no SpA by central reading were identified as axSpA by local evaluation; 8 pts (2.0%) classified axSpA by central reading were no SpA by local evaluation. Furthermore, discrepancies were observed when interested in whether pts fulfilled the imaging and clinical arm within the ASAS axSpA criteria (see table). Twenty-two pts (5.6%) fulfilled the imaging arm by local evaluation, but fulfilled the clinical arm only based on central reading. In contrast only 4 pts (1.0%), who fulfilled only the clinical arm based on local evaluation, were reclassified into the imaging arm by central reading. Conclusions In pts with chronic back pain 10.9% of pts were classified differently based on scores of trained central readers and local evaluation of radiologists. This was due to difference in reading in both MRI-SI and X-SI. However, in a greater proportion of pts the classification did not change even with discrepant reading because of the clinical arm of the ASAS classification criteria. References van den Berg. Ann Rheum Dis 2014. Disclosure of Interest None declared

SAT0262 Should Imaging of the SI Joints be Repeated After 1 Year? Impact on the Classification of Patients According to the ASAS Axial SPA Criteria

Background It is known that in axial spondyloarthritis (axSpA) inflammatory lesions on MRI of the SI joints (MRI-SI) can change over time. The usefulness of repeating imaging in the diagnostic process is unclear. Objectives To investigate how patients with short-term chronic back pain are classified by the ASAS axSpA- criteria at baseline and after 1-year follow-up, focussing on the role of imaging. Methods Patients in the SPACE-cohort (back pain: ≥3 months, ≤2 years, onset <45 years) with (suspicion of) axSpA underwent MRI and X-rays of the SI-joints at baseline and 1-year follow-up. Patients with complete MRI- and X-SI data at both timepoints were included in the analysis (n=185). MRI-SI and X-SI were scored by 3 different well-calibrated readers independently according to the ASAS-definition for a positive MRI and the mNY-criteria, blinded for patient characteristics and time sequence. Fulfillment of ASAS-MRI or mNY-criteria was considered positive if 2/3 readers agreed. At each timepoint, patients were classified according the ASAS axSpA-criteria and grouped in the different arms (imaging arm: mNY+/- or MRI+/-; clinical arm, fulfilment of both arms and possible axSpA). At year one, in contrary to the normal application of the criteria, where a positive feature remains positive:we grouped patients according to the finding at that timepoint, ignoring previous imaging findings. Results At baseline, 92/185 patients (49.7%) fulfilled the ASAS criteria (clinical arm: 53; imaging arm: 15, both arms: 24) (table). At 1 year, 14 additional patients fulfilled the criteria (8 clinical arm; 5 imaging arm only; 1 both arms). After 1 year, in 12 patients MRI-SI became positive. As a result, 14/93 (15.1%) of the no SpA or possible SpA patients at baseline could be classified additionally as axSpA because of additional SpA features (n=8), a positive MRI (n=4) or sacroiliitis according to the mNY-criteria (n=2), On the other hand, MRI-SI became negative after 1 year in 12 other patients. Of these patients, 10 still fulfilled the ASAS criteria (clinical arm (n=7) or both arms (n=3)). Only 4 patients (classified as axSpA at baseline) would be missed if imaging would have been performed only at 1 year (due to negative MRI or x-ray findings). Conclusions In our cohort, a signifcant number of patients with no SpA or possible SpA at baseline developed (additional) SpA features leading to fulfilment of axSpA criteria at year one. However, our data show the robustness of the axSpA criteria and there is only limited evidence for repeating imaging after one year. Disclosure of Interest None declared

SAT0589 Replacing Radiographic Sacroiliitis by Structural Lesions on MRI of the Sacroiliac Joints: Impact on the Classification of Patients According to the Asas Axial SPA Criteria

Background Conventional radiography is the most common used method to detect structural lesions in the sacroiliac joints (SIJ) in axial SpondyloArthritis (axSpA). However, reliability is a problem. Besides inflammatory lesions on MRI, which are used to define a positive MRI in the ASAS criteria, structural lesions are visible on MRI. Objectives To investigate the impact of replacement of x-rays by structural lesions on MRI on the ASAS axSpA classification of patients. Methods Patients in the SPACE cohort (chronic back pain: ≥3 months, ≤2 years, onset <45 years) with (suspicion of) axSpA underwent MRI and X-rays of the SIJs. Three well-calibrated readers, blinded for patient characteristics, read all available baseline MRI-SI (ASAS definition) and X-SI (mod New York). MRI-SI and X-SI were considered positive if 2/3 readers agreed. In addition, MRI T1-weighted images (viewed simultaneously with STIR) were assessed on the presence of structural lesions (in each of the quadrants of each SIJ). Lesions were marked present if 1 lesion was seen on ≥2 consecutive slices. Mean scores of 2 out of 3 agreeing readers (based on ASAS definition) were used. Earlier, we proposed cut-offs to define a positive MRI-SI based on structural lesions (MRI-SI-struct) based on <5% presence among no-SpA patients. These proposed cut-offs are: erosions ≥3, fatty lesions ≥3, fat lesions and/or erosions ≥5. Patients were classified according to the ASAS axSpA-criteria and grouped in the different arms, using the various definitions of MRI-SI-struct instead of X-SI. Results For this analysis 294 patients with complete imaging data were included. Using the cut-off for fatty lesions and/or erosions ≥5, classification did not change in 275+3+8 (286) patients (97.3%) (table). In the remaining 8 patients, 5 patients (1.7%) would not be classified axSpA if only MRI-SI-struct was performed, while 3 patients (1.0%) would be additionally classified as axSpA. Furthermore, an additional 8 patients would be classified by different arms. Very similar results were found when replacing X-rays by the definition of a positive MRI-SI-struct for the presence of fatty lesions or erosions alone (both cut-off of >3), and for the scores of the 2 readers individually. Conclusions The replacement of x-rays by assessment of structural lesions on MRI does not lead to a different ASAS axSpA classification in the majority of the patients;. These data are promising, however, this is in a cohort of patients with a relatively low number of patients fulfilling the axSpA criteria and in the early phases of the disease. Therefore these data need to be confirmed in patients with established disease. Disclosure of Interest None declared

FRI0554 Young Patients with Back Pain and Maximally 1 Spondyloarthritis Feature: Is it Necessary to Test HLA-B27 or Image the Sacroiliac Joints?

Background Axial SpondyloArthritis (axSpA) is a heterogeneous disease. The likelihood of diagnosis varies depending upon the presence of the specific SpA-features. It is debated whether additional examinations (i.e. HLA-B27 testing and imaging of the sacroiliac joints (SIJ)) should be performed in patients with a low suspicion of axSpA (0-1 present SpA-features) after clinical examination, physical examination, CRP/ESR measurement. Objectives To investigate if HLA-B27 testing and imaging of the SIJ is useful in young patients with back pain and maximally 1 SpA feature. Methods The SPACE cohort includes patients with chronic back pain (CBP; ≥3 months ≤2 years, onset <45 years) recruited from 5 participating centres across Europe. All patients underwent full diagnostic work-up: MRI and x-rays SIJ, HLA-B27 testing and assessment of all other SpA-features. Patients were classified according to the ASAS axSpA-criteria and according to the clinical rheumatologist diagnosis. Results In this analysis, 133 patients were included. Of the 38/133 (28.6%) patients without SpA-features; 4/38 (10.5%) were classified according to the ASAS-axSpA criteria after additional investigations (table). Three of them were also diagnosed as axSpA by the rheumatologist. Four additional patients were diagnosed axSpA but did not fulfil the ASAS axSpA criteria. Of the 95/133 (71.4%) patients with 1 SpA-feature; 22/95 (23.2%) patients fulfilled the ASAS criteria via the imaging arm. SpA features in these patients were: 7 IBP, 5 IBD, 4 positive family history for SpA, 3 good response to NSAIDs, 2 raised CRP/ESR, 1 enthesitis. Seventeen of these 22 patients were also diagnosed as axSpA by the rheumatologist. Six additional patients were diagnosed axSpA but did not fulfil the ASAS axSpA criteria. Conclusions In patients with CBP and maximally 1 SpA feature after medical history, physical examination and CRP/ESR measurement, subsequent HLA-B27 testing and imaging led to fulfilment of the ASAS axSpA-criteria in 11% and 23%, respectively. In addition axSpA was the clinical diagnosis in almost twenty percent of this group. Therefore, in patients with maximally 1 SpA feature, axSpA cannot be ruled out without additional imaging and/or HLA-B27 testing. Disclosure of Interest None declared

SAT0195 Is IT Worth to Include MRI of the Spine in the ASAS Classification Criteria for Axial Spondyloarthritis; Data from the Desir-Cohort

Background Spinal MRI lesions suggestive of axial Spondyloarthritis (axSpA) are not included in the ASAS definition of a positive MRI, but do occur in the absence of affected sacroiliac joints (SIJ). It is unknown how often this happens and if it is useful to perform a MRI of the spine in patients (pts) with negative MRI-SIJ Objectives To investigate the prevalence of a positive MRI-spine in pts with short symptom duration and a negative MRI-SIJ Methods Pts aged 18-50 with inflammatory back pain (IBP) (≥3 months, ≤3 years) from 25 participating centers in France were included in the DESIR-cohort (n=708). All available baseline MRIs of the spine were independently scored by 2 well-calibrated central readers who were blind to any other data. MRIs-SI were scored according to the ASAS definition1 (lesions highly suggestive of sacroiliitis plus ≥1 lesion on ≥2 consecutive slices or >1 lesion on 1 slice). Inflammatory lesions on MRI-spine suggestive of spondylitis were scored when visible on ≥2 consecutive slices and according to the ASAS consensus definition2 (≥3 lesions). In case of disagreement, an experienced radiologist served as adjudicator. MRI was considered positive if 2/3 readers agreed Results All pts with MRI-spine and MRI-SIJ (n=650) were included in the analyses. There were 231 pts (35,5%) with a positive MRI-SIJ and 102 pts (15.7%) with a positive MRI-spine; 67 pts (10.3%) were positive for both MRI-SIJ and MRI-spine, 384 (59.1%) were negative for both; and 35 pts (5.4%) had a positive MRI-spine but a negative MRI-SI. Thirty of these were <45 years at symptom onset (entry criterion for ASAS axSpA criteria); 8 of these 30 pts fulfilled the modified New York criteria, 16 of these 30 pts fulfilled the clinical arm of the ASAS axSpA criteria and 6 pts did not fulfil the criteria. All these 6 pts were HLA-B27 negative. Therefore, if the MRI-spine would be considered to count for imaging for the ASAS criteria, 6 additional pts would have been classified and 16 pts would have fulfiled both the imaging and clinical arm; Two of the 5 pts with age >45 years at symptom onset fulfilled the mNY criteria. Overall, only 25 pts (3.8%) had a pos MRI-spine without sacroiliitis on MRI or radiographs Conclusions In 3.8% of IBP pts aged 18-50 ≥3 spinal inflammatory lesions suggestive of axSpA are found in absence of sacroiliitis on MRI or radiograph. Therefore the yield of including MRI-spine as additional imaging criterion in the ASAS axSpA classification criteria is considered unacceptably low References Rudwaleit, ARD 2009;68:1520-7. Hermann, ARD 2012;71:1278-88. Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.4054

FRI0244 Prevalence of MRI Spinal Lesions Typical for Axial Spondyloarthritis in Patients with Inflammatory Back Pain

Background Since 2012, a cut-off value of ≥3 inflammatory lesions was suggested by the ASAS/OMERACT group, as positive MRI of the spine (MRI-spine). Moreover, fatty lesions on MRI-spine are associated with axial Spondyloarthritis (axSpA). Objectives To determine the prevalence of inflammatory (BME) and fatty lesions on MRI of the spine in patients (pts) with and without axSpA Methods Pts aged 18-50 with inflammatory back pain (≥3 months, ≤3 years) from 25 participating centers in France were included in the DESIR-cohort (n=708). All available baseline MRIs were independently scored by 2 well-calibrated readers, blinded to any other data. In case of disagreement, an experienced radiologist served as adjudicator. BME and fatty lesions typical for axSpA were scored when visible on ≥2 consecutive slices. Prevalence of MRI lesions was calculated based on several cut-offs and lesions were considered present if 2/3 readers agreed Results All pts with symptom onset <45 yrs with MRI-spine (n=549) were included in the analyses. Pts fulfilling the ASAS criteria could either fulfill both arms, only the imaging arm or only the clinical arm. The first 2 groups were subdivided; pts with radiographic sacroiliitis (mNY+) & sacroiliitis on MRI (MRI+), pts with mNY+ & no sacroiliitis on MRI (MRI-), pts without radiographic sacroiliitis (mNY-) & MRI+. BME lesions occur in all different subgroups of the ASAS criteria and in pts without axSpA (table). The prevalence in no SpA group (which can be seen as false positives) is only 6.1%. With a cut-off ≥2 BME lesions false positives drop below 5% while the prevalence in the ASAS axSpA groups is still reasonable. Especially prevalence in pts with mNY+ & MRI+ is very high; 61.9% (both arms positive) and 43.8% (imaging arm only positive). Fatty lesions are seen slightly less often seen in all patient groups. However the same trend is seen as with BME lesions; Even with cut-off ≥1 the prevalence in no SpA group is low (5.5%), with cut-off ≥2 false positives drop below 5% and again pts with mNY+ & MRI+ have the highest percentage of spinal fatty lesions Conclusions In a low percentage of pts without axSpA BME and fatty lesions is found indicating that spinal BME and fatty lesions are specific for patients with axSpA. These lesions are especially prevalent in pts with sacroiliitis on imaging. In this cohort, a cut-off ≥2 or ≥3 BME lesions and similarly ≥2 or ≥3 fatty lesions discriminate best between pts with and without axSpA Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.1986

SAT0196 Scoring of Spinal Lesions Compatible with Axial Spondyloarthritis on MRI in Clinical Practice by Local Radiologist or Rheumatologist in Desir; Comparison with Central Reading

Background In clinical practice radiologists and rheumatologists assess whether lesions compatible with axial SpondyloArthritis (axSpA) are present on spinal MRI Objectives To compare the results of local readings (LocR) to centralized reading (CentR) as external standard of BME and structural lesions on MRI-spine, in patients (pts) with inflammatory back pain (IBP) Methods Pts aged 18-50 with recent IBP (≥3 months, ≤3 years) from 25 participating centers in France were included in the DESIR-cohort (n=708). All available baseline MRIs-spine were scored on BME and structural lesions as present, absent or doubtful by the local radiologist/rheumatologist who might have access to clinical data. In addition, 2 well-calibrated centralized readers independently scored the same MRIs for BME lesions and structural lesions (fatty lesions, erosions and (bridging) syndesmophytes). In case the centralized readers disagreed, an experienced radiologist served as adjudicator. Agreement between CentR and LocR was calculated excluding the cases assessed as doubtful by LocR (kappa κ) Results BME/structural lesions were in 492/492 pts scored by a radiologist, 206/205 by a rheumatologist and in 32/32 pts by both. The k agreement between LocR and CentR was 0.27 for BME lesions and 0.13 for structural lesions. For radiologists, κ=0.36 for BME, and κ=0.15 for structural lesions. For rheumatologists κ=0.006 for BME and κ=0.12 for structural lesions. Overall, local specialists are highly overrating positive findings: 42.3% and 85.7% of the positive MRIs for BME are scored negative by the central read (radiologists and rheumatologist respectively). Similarly findings for structural lesions: 48.4% and 70% of MRIs positive for structural lesions are scored normal by central reading Conclusions Both local radiologists, but especially rheumatologists overrate the presence of BME lesions and structural lesions on MRI of the spine compared to trained central readers. These results do not even take doubtful cases into account Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.5456

AB0982 Comparison of the Performance of the BASRI and Msasss in Patients with Early Inflammatory Back Pain from the DESIR Cohort

Background For assessing structural damage in AS on spinal X-rays Bath Ankylosing Spondylitis Radiology Index (BASRI) and modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) scoring systems can be used Objectives To present the prevalence of abnormalities based on the BASRI and mSASSS in patients (pts) with recent inflammatory back pain (IBP) and to compare these 2 scores Methods Pts aged 18-50 with recent IBP (≥3 months, ≤3 years) from 25 participating centres in France were included in the DESIR (Devenir des Spondylarthropathies Indifferenciées Récentes)-cohort (n=708). Available baseline spinal X-rays (cervical and lumbar) were scored by 2 well-calibrated central readers independently, blinded for clinical data. When readers disagreed, an experienced radiologist served as adjudicator. BASRI and mSASSS were calculated from the mean of the scores of the 2 readers (and adjudicator if applicable). Pts were classified according to the ASAS axial SpondyloArthritis (ASAS axSpA) criteria into pts fulfilling the imaging arm, either fulfilling or not fulfilling the modified New York (mNY) criteria, fulfilling the clinical arm and not fulfilling (no-axSpA pts) the criteria Results Pts with complete X-ray data (n=599) were included in these analyses. Overall, 559 pts (93.3%) had no definite abnormalities assessed by mSASSS <2, and 564 (94.2%) by BASRI <2; 93.0% and 93.5% within the ASAS axSpA group (n=431), respectively (see table). A BASRI of ≥2 was scored more frequently in the imaging arm compared to the clinical arm and no-axSpA pts (table). When comparing mSASSS and BASRI readings, using a cut-off of ≥2 (definite abnormalities) for both scoring methods, we found a very high percentage of agreement in all the different patient groups: range 95.4% to 98.2%. Only in few pts syndesmophytes were found (table). More syndesmophytes were present in cervical spine than in lumbar spine. The number of syndesmophytes in cervical vs lumbar spine was 6 vs 3 in the no-axSpA group, 6 vs 1 in the clinical arm, 5 vs 1 in the imaging mNY-group, and 8 vs 1 in the imaging mNY+ group ASAS axSpA, n=431 No-SpA, n=168 Imaging arm mNY+ Imaging arm mNY− Clinical arm n=131 n=110 n=190 mSASSS <2 123 (93.9%) 100 (90.9%) 178 (93.7%) 158 (94.0%) mSASSS ≥2 & <5 4 (3.1%) 8 (7.3%) 9 (4.7%) 7 (4.2%) mSASSS ≥5 & <10 3 (2.3%) 2 (1.8%) 1 (0.5%) 0 mSASSS ≥10 & ≤15 1 (0.8%) 0 2 (1.1%) 3 (1.8%) Total BASRI <2 117 (89.3%) 104 (94.5%) 182 (95.8%) 161 (95.8%) Total BASRI =2 10 (7.6%) 4 (3.6%) 7 (3.7%) 5 (3.0%) Total BASRI =3 2 (1.5%) 2 (1.8%) 0 1 (0.6%) Total BASRI =4 2 (1.5%) 0 1 (0.5%) 0 Total BASRI =5 0 0 0 1 (0.6%) No syndesmophytes 125 (95.4%) 105 (95.5%) 182 (95.8%) 161 (95.8%) ≥1 & <5 syndesmophytes 6 (4.6%) 3 (2.7%) 8 (4.2%) 5 (3.0%) ≥5 & <10 syndesmophytes 0 2 (1.8%) 0 2 (1.2%) Conclusions The agreement between mSASSS and BASRI ≥2 is very high in all groups. Abnormalities typical for AS such as syndesmophytes are generally infrequent in this early cohort, but if observed, syndesmophytes are more frequent in the cervical spine compared to the lumbar spine. An mSASSS and BASRI of ≥2 is more often seen in pts fulfilling the ASAS classification criteria compared to no-SpA pts Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.2662