AB1009 Concordance between "A Positive MRI of the Sacroiliac Joints" Based on the Local Reading versus A Centralised Reading: Experience from the Desir-Cohort. (10th June 2014) - van den Berg, R.
Abstract : Background: Reading of MRIs of the sacroiliac joints (MRI-SI) in clinical trials is usually performed by ≥1 trained readers while in daily practice this is done by local radiologists/rheumatologists. However, this varies in cohorts and in the DEvenir des Spondylarthropathies Indifferenciées Récentes (DESIR)-cohort, MRIs-SI at inclusion were first read by the local radiologist/rheumatologist, then by central readers. The impact of reading by multiple readers in various centres as in daily practice, instead of a centralized reading, is unknown. Objectives: To compare the local reading (LocR) to centralized reading (CentR) regarding the presence or absence of inflammation on MRI-SI. Methods: The 25 participating centers included patients aged 18-50 with inflammatory back pain (IBP; ≥3 months, ≤3 years) in the DESIR-cohort (n=708). Available baseline MRIs-SI were read by local radiologists/rheumatologists with access to clinical and laboratory data, on the presence of inflammatory lesions in both SI-joints. A grade 0 corresponds to "normal", a grade 1 to "doubtful", and a grade 2 to "definite inflammatory lesions". For this analysis, a positive MRI was defined as at least one SI-joint marked grade 2. Next, 2 well-calibrated central readers independently read all MRIs-SI according to the ASAS definition 1, blinded for clinical and laboratory data. In case the readers disagreed, an experienced radiologist served as adjudicator. An MRI-SI was marked positive if 2/3 readers agreed. Agreement between the 2 central readers, between LocR and CentR and between LocR and the central readers separately was calculated (Kappa; % agreement). Results: In this analysis patients with complete MRI-SI data (n=663) were included. Inter reader agreement between the 2 central readers is acceptable (Kappa 0.73), and the percentage agreement (87.5%) is good (table). The adjudicator scored 84/663 (12.7%) MRIs-SI because of disagreement between the 2 central readers. Comparison between CentR (2/3) and LocR shows the same levels of agreement (kappa 0.70, % agreement 86.6%; table). In 38/663 patients (5.7%), the MRI-SI was positive by LocR but negative by CentR; in 51 patients (7.7%) it was the other way around. There was no difference in agreement between LocR and CentR if MRIs-SI were scored by local rheumatologists or by local radiologists (data not shown). Comparisons of LocR versus the separate readers show very similar results (table). Conclusions: Both inter reader agreement between the 2 central readers and agreement between the local and centralized readings is acceptable to good. This indicates that local rheumatologists/radiologists perform as good as trained readers in identifying inflammation on MRI-SI in patients with recent onset IBP, thereby suggesting that MRI-SI is a reliable assessment in diagnosing and classifying the majority of patients with spondyloarthritis. References: Rudwaleit ARD 2009;68:1520-7 Disclosure of Interest: None declared DOI: 10.1136/annrheumdis-2014-eular.3510