Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.

The New ASAS Criteria for Axial SpA Does Not Predict the Development of mNYC AS at 8 Years in a Cohort of Very Early IBP Patients.

Aydin2,  Sibel Z., Bennett1,  Alex, Emery2,  Paul, McGonagle2,  Dennis, Marzo-Ortega2,  Helena

Defence Medical Rehabilitation Centre, Headley Court, Epsom, Surrey, United Kingdom
Section of Musculoskeletal Diseases, The Leeds Institute of Molecular Medicine. University of Leeds, Leeds, United Kingdom


Axial SpA can be identified by using the new ASAS criteria. We aimed to test the predictive value of the imaging (MRI) and HLA-B27 arms of these criteria for the future development of Ankylosing Spondylitis (AS).


An inception cohort of 33 patients with early inflammatory back pain (IBP) (median symptom duration 24 weeks) were retrospectively evaluated against both arms (imaging and HLA-B27) of the criteria. Plain radiographs and MRIs of the SIJs at baseline and radiographs after a mean duration of 8-years were assessed. MRIs were scored according to the ASAS definition of a "positive MRI" and the predictive value of both arms was compared. Further scoring to identify patients with severe MRI sacroiliitis (grade 3 according to the Leeds MRI SIJ Scoring System) was also available.


All patients could be classified as axial SpA with more patients fulfilling the imaging (85%, n=28/33) than the clinical arm (58%, n=19/33) of the criteria. Eight patients with baseline evidence of radiographic sacroiliitis fulfilling the mNYC were excluded from the predictive analysis. Of the rest (25/33), n=4 patients developed AS at follow-up (all had a positive baseline MRI and 2 were HLA-B27+ve) and 11/33 had an increase in the radiographic sacroiliitis scores at 8 years. For prediction of new AS the MRI arm showed 100% sensitivity and 19% specificity whereas the HLA-B27 arm had 50% sensitivity and 43% specificity. No differences were seen between both arms for developing new AS or for progression of sacroiliitis when applying the ASAS definition of a positive MRI.

However an association was seen between development of AS (PPV 67%, NPV 91%, LR: 10) and progression of sacroiliitis (PPV 71%, NPV 76%, LR: 4.8) when using the Leeds definition of severe MRI sacroiliitis.


Neither arm of the new ASAS classification criteria predicted the progression of radiographic sacroiliitis (including the development of mNYC AS) over an 8 year period in this cohort of very early IBP. This may be due to the inclusion of "mild" MRI sacroilitis in the ASAS definition of a "positive MRI" since severe MRI sacroiliitis was a better predictor.

Table 1. New AS or worsening of sacroiliitis by X-rays according to the MRI findings and HLA-B27 positivity

  Positive MRI (ASAS definition)Severe MRI (Leeds Scoring System)HLA-B27
New AS (mNYC) n = 25+401220.057221
 -174 120 129 
Progression of sacroiliitis n = 33+1010.6560.03740.7
 -174 219 1110 

To cite this abstract, please use the following information:
Aydin, Sibel Z., Bennett, Alex, Emery, Paul, McGonagle, Dennis, Marzo-Ortega, Helena; The New ASAS Criteria for Axial SpA Does Not Predict the Development of mNYC AS at 8 Years in a Cohort of Very Early IBP Patients. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :553
DOI: 10.1002/art.28322

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