Session Type: Poster Session (Sunday)
Session Time: 9:00AM-11:00AM
Background/Purpose: Active MRI lesions typical of axSpA were reported in 61.6% and 2.2% of axSpA and not-axSpA patients, respectively, from the ASAS classification cohort (ASAS-CC)1. Discrepancy between local and central reader evaluation of MRI scans regarding could result in differences in numbers of patients fulfilling the imaging arm of the ASAS classification criteria. But final classification may not be impacted if discrepant patients still fulfill the clinical arm. We aimed to assess the impact of reader discrepancy in detection of active MRI lesions on the number of patients classified as having axSpA in patients recruited to the ASAS-CC.
Methods: MRI images of the sacroiliac joints (SIJs) were available from 253 cases in the ASAS-CC, and these also had clinical and radiographic data. Seven central readers from the ASAS-MRI group recorded MRI lesions in an eCRF that included wording of lesions defining active lesions typical of axSpA in the SIJ (MRI-active) that was exactly the same as in the original ASAS-CC eCRF permitting comparisons between central and local site readers. Active lesions were deemed to be present according to majority agreement (≥4/7) of central readers and also any 2 central readers. We calculated the number of patients that were classified differently after central evaluation for overall fulfilment of the ASAS criteria and for the imaging arm.
Results: Discordance between central and local readers for detection of MRI-active was recorded in 70(27.1%) and 47(18.2%) of cases according to 2-reader and majority (≥4/7) central reader data, respectively (kappa (95%CI) of 0.62(0.52-0.71) and 0.58(0.49-0.67)). With central reading as external standard the false-positive rate for MRI-SI was 47.9% and 33.3% (‘local overcall’) for 2-reader and majority reader data. False-negative rate was 5.4% and 3.1%, respectively. A total of 159(62.8%) patients fulfilled the ASAS axSpA criteria based on local-reading, and 149(58.9%) and 143(56.5%) patients based on 2-reader and majority central-reading, respectively (Table). 25(9.9%) and 20(7.9%) patients who were classified as axSpA after local reading were no longer classified as axSpA after 2-reader and majority reader central evaluation. 7(2.8%) and 4(1.6%) classified as axSpA after central reading were not after local assessment. When fulfillment of the imaging arm was required (irrespective of the clinical arm), 45(17.8%) and 31(12.3%) cases were classified as axSpA after local MRI inflammation reading but not after 2-reader and majority central reading evaluation, and 5(1.9%) and 3(1.2%) cases that were not classified as axSpA after local MRI inflammation reading were classified as axSpA after central reading.
Conclusion: Despite substantial overcall for positive MRI SIJ inflammation by local readers when central readers are considered the reference standard, the number of patients classified as having axSpA did not change substantially. However, it is unclear whether reader discrepancy could have affected the final diagnosis, the gold standard for assessment of the performance of the ASAS criteria. Also, the gap of >10 years between local and central reading has to be taken into account.
1. Rudwaleit et al. Ann Rheum Dis 2009;68: 777-83
To cite this abstract in AMA style:Maksymowych W, Juhl Pedersen S, Weber U, Machado P, Baraliakos X, Sieper J, Wichuk S, Poddubnyy D, Rudwaleit M, van der Heijde D, Landewé R, Paschke J, Østergaard M, Lambert R. What Is the Impact of Discrepancy Between Central and Local Readers in Evaluation of MRI Scans on the Classification of Axial Spondyloarthritis? Data from the ASAS Classification Cohort Study [abstract]. Arthritis Rheumatol. 2019; 71 (suppl 10). https://acrabstracts.org/abstract/what-is-the-impact-of-discrepancy-between-central-and-local-readers-in-evaluation-of-mri-scans-on-the-classification-of-axial-spondyloarthritis-data-from-the-asas-classification-cohort-study/. Accessed April 11, 2021.
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