Methods: The reliability exercise was performed using a REDCap. One-hundred-fifty anonymized still images from AA, were assessed (50 each from chronic and acute GCA, and 50 from healthy individuals). Chronic GCA patients had a disease duration of more than one year and were in remission. Acute GCA patients had new-onset disease with glucocorticoid treatment duration ≤1 week. The members of the OMERACT Large Vessel Vasculitis Ultrasound Working Group (n=23, all ultrasound experts in GCA) were asked to assign all images to the categories of normal, acute GCA or chronic GCA applying the definitions agreed in previous Delphi exercises. In order to assess the intra-observer reliability, all task force members were asked to repeat the reliability exercise in a time range of at least two weeks later and using the same images presented in a different order. Light’s κ were used for evaluating intra- and inter-reader reliability, respectively. Κ values of 0–0.2 were considered slight, 0.2–0.4 fair, 0.4–0.6 moderate, 0.6–0.8 substantial and 0.8–1 excellent.
Results: The response rate for both rounds was 100%. The reliability of the new OMERACT definition for the US appearance of chronic GCA of the AA was substantial to excellent with Light’s kappa values of 0.79-0.80 for inter-reader reliability and mean Cohen-kappa values of 0.88. The mean inter-rater agreements were 86-87%. The mean intra-reader agreements were 92% (Table 2).
Conclusion: Inter- and intra-observer agreement on the evaluation of US still images from normal, acute and chronic GCA AA was substantial to excellent when applying the new OMERACT definitions for key elementary US lesions in GCA of the AA. Further exercises are planned in order to test the reliability in patients with chronic GCA US changes of the AA.
|Journal||Arthritis & Rheumatology|
|Publication status||Published - 1 Oct 2020|