198. Lessons learned from a multidisciplinary approach to giant cell arteritis diagnosis
Creators: name: Smith1, Kate
name: Borsha Sarker1
name: Richard J. Wakefield1, 2
name: Thurkka Rajeswaren3
name: Taze4, Dilek
name: Charabarty4, Aruna
name: Barr5, Andrew
name: Sarah L. Mackie1, 2
Publisher: name: Zenodo
Year: 2022
Subjects: Vasculitis
ANCA
Abstracts
Giant Cell Arthritis
MPA
GPA
EGPA
Takayasu
IgA vasculitis

description: <strong>Background: </strong>During the first year of offering TAUS, we advised clinicians not to change their usual practice with regard to requesting TAB. We set up a monthly multidisciplinary team meeting (MDTM) with pathologists and sonographers to facilitate team learning. Here, we focus on lessons learnt from the results of patients who had both TAUS and TAB. <strong>Methods: </strong>A positive ultrasound was defined as at least one non-compressible temporal artery halo and/or axillary artery intimal-medial thickening (&gt;1.0mm) . A positive biopsy required the presence of inflammatory infiltrate in one or more arterial wall layers. <strong>Results: </strong>279 consecutive patients with suspected GCA had a first TAUS between 01/01/2019 and 30/08/2020. Mean age was 70 (range: 46-100); 74% female. 82/279 had TAB: results are compared with TAUS in Fig. 1. The sensitivity and specificity of TAUS compared to TAB was 17/23(74%) and 44/59(75%). 4 of the 5 TAB+/TAUS- cases were histologically mild: adventitial-invasive (n=2), focal inflammation (n=2). The fifth had clinically and histologically typical GCA but the TAB was performed before the ultrasound, suggesting that only one temporal artery branch was involved. In no case did the discrepancy seem likely to be explained by steroid therapy before TAUS (1 week or less for all 5). Of the 9 TAB-/TAUS+ cases, 2 TAUS showed focal halo (skip lesions) in cases with typical GCA clinically. 5 TAB had features of vascular ageing including intimal thickening, and had acute bacteraemia (n=2) or extensive prior history of atherosclerosis (n=3). The remaining 2 were genuinely uncertain cases and were both treated for GCA acknowledging diagnostic uncertainty. Re-evaluating the equivocal ultrasound scans, six of the seven cases could be attributed to “bifurcation halo” ; in these cases, either the vessel was not fully compressible, or it had a halo appearance but was compressible. If the equivocal TAUS had been reclassified as negative, the specificity of TAUS compared to TAB would have improved to 50/59 (85%) without detriment to sensitivity. <strong>Conclusions: </strong>In evaluation of suspected GCA, TAUS and TAB are usually but not always concordant. Using the MDTM and audit of discrepant results has enabled us as a team to learn lessons: The MDTM enables discrepant results to be discussed and this feedback allows clinical or imaging thresholds to be refined. TAB can detect cases that TAUS misses due to focal/adventitial inflammation. TAUS can detect cases that TAB misses due to skip lesions sparing sections of artery. False positive TAUS is usually explained by age-related intimal thickening. Isolated halo sign at a vascular bifurcation is not sufficient for a positive TAUS. If MDTM reviews all cases, genuinely ambiguous cases are rare. <strong>Disclosures:</strong> SM: Support from Roche/Chugai to attend EULAR 2019. Support from Pfizer to attend ACR 2021. Consultancy on behalf of my institution for: Roche/Chugai, AbbVie, AstraZeneca, Sanofi, Pfizer. <strong>Figure 1.</strong>