Pos0930 Utility of Ultrasound Monitoring Giant Cell Arteritis Large Vessel in Clinical Practice

Background: In patients with untreated giant cell arteritis (GCA), ultrasound (US) of cranial and extracranial large arteries (LV) reveals a homogeneous and hypoechoic wall thickening, deemed as the 'halo sign'. Once therapy is started, the halo sign and particularly the number of segments with halo (halo count) and the sum scores of the halo intima-media thicknesses (IMT), appears to be sensitive to change, with a rapid reduction in IMT in temporal arteries, and a very delayed or, in some cases, even absent in axillary and LV arteries. Objectives: The main objective of this study was to study the longitudinal assessment and predictive value of LV US through OMERACT GCA Ultrasonography Score (OGUS) 1 and halo count, and the value of added subclavian artery to assess the sensitivity to change of LV US in the longtime US follow-up of GCA. Methods: Longitudinal retrospective observational US study of LV-GCA patients. All were diagnosed by the doctor in charge and the diagnosis was confirmed during all the follow-up. Patients underwent US evaluation at diagnosis and during follow-up and images and videos were recorded for scores calculation. We calculate OGUS LV-modified, which includes only LV, axillary arteries (OGUS-2LV), and we check the value of added subclavian artery to the OGUS-2LV, so we calculated a modified OGUS including axillary and subclavian arteries (OGUS-4LV). Likewise, we calculate halo count LV, defined as the number of LV is showing a halo sign and/or IMT ≥ 1mm. We calculated Halo count-2LV which included only axillary arteries and Halo count-4LV which included both axillary and subclavian arteries. Reliability of the measures in our group showed an ICC inter-reader (0.972 (95% CI 0.960-0.980). For descriptive analyses frequencies and percentages for qualitative variables and mean and standard deviation (SD) values for continuous variables were used. Mann–Whitney U test was used for means comparison. Results: The study includes 39 patients in the basal visit, mean age 75.5±7.3 years, 18 women (46%). All have US examination of axillary and subclavian arteries at different clinical visits. Table 1 shows how the LV US reflects the mean response to treatment of the patients and how this response occurs very late compared to what we know about cranial GCA. The comparison between the different scores OGUS-4LV, OGUS-2LV, Halo count-4LV and Halo count-2LV show as specially OGUS-4LV that adds the subclavian to axillary arteries is the most sensitive to change, showing mean significant responses from the sixth month of treatment, while the halo count does not achieve this until 2 years of follow-up. The inclusion of subclavian artery in the study of LV-GCA increased the diagnosis of LV in a 10%, and also increased the sensitivity to change in the assessment. The normalization of the IMT vessel wall below the normal accepted cut-off occurs slowly with figures that depend on the indices used and vary from 45.5 to 36.4% at 2 years or from 91 to 73% at 3 years (see Table 1). Halo count =0 and OGUS below 0.8 are predictive of absence of relapse in the next months and probably open the concept of remission by image. Figure 1 shows the behavior of OGUS-LV in every patient in the follow-up. Table 1. Ultrasound scores in the follow-up of LV-GCA patients. n=number; SD=Standard Deviation; OGUS =OMERACT GCA Ultrasonography Score; 4LV=4 vessels, axillary and subclavian bilateral; 2LV=2 vessels, axillary bilateral; LV= Large Vessels; *pConclusion: Ultrasound scores have sensitivity to change as response to the treatment. The normalization of the IMT vessel wall can be achieved slowly in most patients during the follow-up. OGUS and halo count have predictive value about relapse. REFERENCES: 1 Dejaco C, Ponte C, Monti S, et al. The provisional OMERACT ultrasonography score for giant cell arteritis. Ann Rheum Dis. 2023;82(4):556-564. doi:10.1136/ard-2022-223367. Acknowledgements: NIL. Disclosure of Interests: None declared.