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SAT0207 Reading of the Sacroiliac Joints on Plain Radiographs: Agreement between Clinical Practice and Trained Central Reading of the Desir-Cohort
  1. R. van den Berg1,
  2. G. Lenczner2,
  3. A. Feydy3,
  4. D. van der Heijde1,
  5. M. Reijnierse1,
  6. A. Saraux4,
  7. A. Rahmouni5,
  8. M. Dougados6,
  9. P. Claudepierre7
  1. 1LUMC, Leiden, Netherlands
  2. 2Clinique Hartmann, Neuilly Sur Seine
  3. 3Paris Descartes University, Cochin Hospital, Paris
  4. 4Hôpital de la Cavale Blanche, Brest
  5. 5Hôpital Henri Mondor, Créteil
  6. 6maxime.dougados@cch.aphp.fr, Paris
  7. 7Université Paris Est Créteil, Chenevier-Mondor Hospital, Créteil, France

Abstract

Background In daily practice, radiologists/rheumatologist judge sacroiliac (SI) joints on X-rays (X-SI). However, reliable identification of radiographic sacroiliitis is difficult. Consequently, large inter- and intra-observer variations have been reported, even after specific training1. In cohorts and clinical trials the reading is usually done by ≥1 trained readers. However, in the DEvenir des Spondylarthropathies Indifferenciées Récentes (DESIR)-cohort, X-SIs at inclusion were first read by the local radiologist/rheumatologist, then by centralized read.

Objectives To compare the local (by multiple readers in various centers) to centralized read (by a few trained readers) on sacroiliitis yes/no.

Methods Patients (pts) aged 18-50 with inflammatory back pain (IBP; ≥3 months, ≤3 years) from 25 participating centers were included in the DESIR-cohort (n=708). Available baseline X-SIs were read by local radiologists/rheumatologists with access to clinical data, according to a method derived from the modified New York (mNY) criteria2. Grade 2 and 3 from the mNY were pooled together in 1 combined grade “DESIR-2”. Local sacroiliitis was defined by at least unilateral grade ≥DESIR-2. Next, 2 well-calibrated centralized readers independently read all X-SIs according to the original mNY, blinded for clinical data. In case of disagreement, an experienced radiologist was adjudicator. An X-SI was marked positive if 2/3 readers agreed on bilateral ≥2 or unilateral ≥3. Agreement between the 2 centralized readers, and between the local and centralized read was calculated (Kappa; % agreement).

Results Pts with complete X-SI data (n=689) were included in this analysis. Inter reader agreement between the 2 centralized readers is moderate (Kappa 0.54), while percentage agreement (84.3%) is good (table). The low Kappa can partially be explained by the high numbers of normal X-SIs. However, the adjudicator needed to read 108/689 X-SIs (15.7%) because of disagreement among the 2 centralized readers. Comparison between the centralized and the local read shows similar levels of agreement (table). Overall, more X-SIs are read positive by local readers (n=184) than by centralized readers (n=145). In 77 pts, X-SI was read positive by local readers but negative by centralized read; in 38 pts it was the other way around.

Conclusions Agreement between the centralized and local read, but also the inter reader agreement between the 2 centralized readers, is moderate, thereby showing that early detection of sacroiliitis on X-SIs is a challenge. In patients with recent onset IBP, trained readers do not perform better than local rheumatologists/radiologists in recognizing sacroiliitis on X-SI, suggesting that the role of X-SI as diagnostic criterion for axSpA should be re-evaluated.

References

  1. van Tubergen ARD 2003;62:519-25.

  2. van der Linden A&R 1984;27:361–8.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.2131

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