SAT0639 Interobserver agreement of the omeract ultrasonographic criteria for the diagnosis of calcium pyrophosphate deposition disease at the wrist, among panel of radiologists and rheumatologists

Background The OMERACT ultrasound (US) task force subdivision “US in CPPD” has created definitions for US identification of crystal deposits in joints and tested interobserver agreement for several joints1. The knee and the wrist were the most reliable sites for assessing CPPD. Objectives To assess whether the high level of inter-observer agreement of US for the detection of Calcium Pyrophosphate Deposition Disease (CPPD) in the triangular fibrocartilage complex (TFCC) of the wrist found by the experienced rheumatologists of the OMERACT group2 could be reproduced in real life Methods The OMERACT US criteria for identification of CPPD were utilised for this exercise on pre-recorded static images using a dichotomous score among several radiologists (n=2) and rheumatologists (n=5) with varying level of experience in musculoskeletal ultrasonography (range: 2–10 years). Firstly, the same 15 US images of the wrist that had been evaluated by the OMERACT panel were sent for evaluation to the local participants in order to calculate the inter-observer agreement. Secondly, 22 additional wrist US images extracted from locally performed examinations, in patients with a high suspicion of CPPD arthritis were evaluated. These local US examinations were performed in real life conditions, by different operators, on different machines and without prior standardisation of the procedure. For comparison, interobserver of wrist radiographs was also evaluated for all local patients Results The mean overall agreement and kappa values on the OMERACT panel US images were 0.89 and 0.78 respectively. These values are similar to those obtained previously by the OMERACT panel during the web exercise with the same images (0.80 and 0.68 respectively). The interobserver agreement was lower with the local US images (0.70 and 0.49 respectively), probably due primarily to the absence of strict standardisation of US procedure and inferior image quality. For comparison, the performance on the local radiographs was similar (0.70 and 0.47 respectively). Conclusions Our results confirm that the new OMERACT US definitions for assessing wrist CPPD are reliable when applied to pre-recorded static images. Scanning technique and standardisation of the procedure appear to be an important aspect with regards to the assessment of CPP deposition at the wrist. References [1] Filippou G, Sc Definition and reliability assessment of elementary ultrasonographic findings in Calcium Pyrophosphate Deposition Disease. Results of an international multi-observer study by the OMERACT Calcium Pyrophosphate Deposition Disease Ultrasound sub-task force. J Rheumatol2017. [2] Filippou G. How to identify Calcium Pyrophosphate Deposition Disease by Ultrasound: the reliability of the OMERACT definitions in an extended set of joints. An international multi-observer study by the OMERACT Calcium Pyrophosphate Deposition Disease Ultrasound sub-task force in revisionAnn Rheum Disease. Disclosure of Interest None declared