POS1430 RELIABILITY OF THE OMERACT GIANT CELL ARTERITIS ULTRASOUND SCORE (OGUS): RESULTS OF A PATIENT-BASED EXERCISE OF VASCULAR ULTRASONOGRAPHY EXPERTS AND NON-EXPERTS
Authors: C. Duftner, N. Redlinger, G. Bruyn, V. Chadachan, S. Chrysidis, M. Correyero-Plaza, B. Dalsgaard Nielsen, B. Dasgupta, E. De Miguel, A. Diamantopoulos, D. Reffat, G. Fulvio, N. Gkikopoulos, W. Hartung, A. Hocevar, V. A. Kurteva, E. Manger, P. Mercatelli, I. Midtgard, S. Monti, R. Müller, K. Mykkänen, C. Ponte, A. C. Sarbu, L. Seitz, W. A. Schmidt, C. Dejaco
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> In giant cell arteritis (GCA), various ultrasound composite scores, including the provisional OMERACT GCA ultrasonography score (OGUS), the Southend Halo score and the Halo count, have recently been introduced as a monitoring tool for clinical trials [1,2]. Patient-based reliability of these ultrasonography (US) composite scores remain elusive so far. <h3>Objectives:</h3> To test the reliability of the OGUS and the other US scores in a patient-based reliability exercise involving experts and non-experts in vascular ultrasonography. <h3>Methods:</h3> Twelve experts and 12 non-experts were asked to evaluate 6 GCA patients. Each patient was scanned twice (2 rounds separated by ≥3 hours) by each participant. Experts had a half-day meeting ahead to align on US settings and procedures. Non-experts received a training module (90 minutes of theoretical and 240 minutes of practical instructions) after round 1. US examinations were conducted at bilateral common superficial temporal arteries, frontal and parietal branches as well as the axillary arteries. The Intima-media complex was measured at the thickest site of the deep wall of individual arteries, preferentially in longitudinal scan to calculate the OGUS, the Southend score and the Halo count. In case of missing values, a normalized score was calculated by considering the available segments. Inter- and intra-reader reliability were tested by Intraclass correlation coefficient (ICC). <h3>Results:</h3> Mean age of GCA patients was 78±5.1 years, 2 (33%) were female. All had established disease and were in clinical remission, median disease duration was 22.5 (IQR 16.3-28.3) months. Experts and non-experts had a median of 16.5 years (IQR 9.8-20.0) and 1.8 years (IQR 0-3.3) of experience with vascular US, respectively. According to experts, all patients had at least one pathological vessel, mean OGUS was 0.83 (±0.07), mean Southend score was 19.0 (±4.6) and mean Halo count was 2.8 (±1.4). As depicted in Table 1, expert inter-rater ICC of the OGUS was moderate in both rounds, fair for the Southend score and the Halo count in round 1 and moderate in round 2. Expert intra-rater reliability was good for all scores. For non-experts, inter-rater reliability was poor in round 1 for all scores as well as for individual measurements. In round 2, a moderate reliability was found for the OGUS, the normalized Halo count and individual IMT measurements, while reliability remained poor for the normalized Southend score (detailed in Table 1). <h3>Conclusion:</h3> We demonstrate fair to moderate inter-rater reliability and good intra-rater reliability of the OGUS, the Southend score and the Halo count among experts. A short training program for non-experts improved their inter-rater reliability. <h3>REFERENCES:</h3> [1] Dejaco C, Ponte C, Monti S, et al. The provisional OMERACT ultrasonography score for giant cell arteritis. Ann Rheum Dis 2023;82:556-64. [2] van der Geest KSM, Borg F, Kayani A, et al. Novel ultrasonographic halo score for giant cell arteritis: assessment of diagnostic accuracy and association with ocular ischaemia. Ann Rheum Dis 2020;79:393–9. <h3>Acknowledgements:</h3> We thank the Austrian team of Canon for providing the Ultrasound machines, used in the reliability exercise. <h3>Disclosure of Interests:</h3> <b>None declared.</b>