192. Too Many Ultrasounds? Developing Referral Criteria for a Fast-Track Temporal Artery Ultrasound Service
Creators: name: Thurkka Rajeswaran1
name: Smith2, Kate
name: Borsha  Sarker2
name: Richard  Wakefield2, 3
name: Andrew  Barr4,
name: Sarah Mackie2, 3
Publisher: name: Zenodo
Year: 2022
Subjects: Vasculitis
ANCA
Abstracts
Giant Cell Arthritis
MPA
GPA
EGPA
Takayasu
IgA vasculitis

description: <strong>Background: </strong>In January 2019 we introduced temporal and axillary ultrasound (TAUS) to the giant cell arteritis (GCA) diagnostic service at Leeds Teaching Hospitals Trust. Over the subsequent year we saw a steady increase in referral numbers. During the 2020 COVID pandemic, almost all referrals were sent for TAUS, but false-positives were sometimes observed in low-probability cases, usually due to atherosclerosis; this has been reported by others (De Miguel et al., 2017, Fernández-Fernández et al., 2020). The increasing number of TAUS conducted per week also raised concerns about sustainability of the service. However, judgement of pre-test probability, even using risk scores, requires face to face evaluation by an individual with clinical expertise in GCA; this may delay referral for TAUS for patients with medium or high pre-test probability of GCA. As part of our service evaluation, we therefore examined our retrospective data to determine whether restricting TAUS to those with CRP&gt;5.0mg/L was a reasonable option. <strong>Methods: </strong>This was part of our ongoing service evaluation and was a retrospective analysis. We examined consecutive patients who had undergone TAUS for new presentation of GCA (excluding those having repeat scans for relapse assessment). The highest CRP before starting steroids was recorded, alongside the GCA diagnosis, defined by consultant confirmation of GCA diagnosis and continued treatment for GCA for at least 6 months following first presentation. <strong>Results: </strong>We examined consecutive scans between 21st Jan 2019 and 25th Aug 2020. Of 293 scans done, 242 were new presentations of suspected GCA. Of these 242, 96 patients with new suspected GCA had a normal CRP (&lt;5mg/L). Of these 96, five patients were ultimately diagnosed with GCA. However, of these five, three were already taking long-term, low-dose steroids for polymyalgia rheumatica (PMR), and therefore this cannot be said to be a pre-steroid CRP. The fourth, who presented with visual loss, may have self-treated with prednisolone in the community prior to having the CRP drawn; over time, he had two negative TAUS and two negative TABs but was treated for GCA. The fifth had a negative TAUS and negative TAB but was treated for GCA due to a symptomatic response to steroid therapy. <strong>Conclusions: </strong>After the introduction of TAUS for suspected GCA, nearly 40% of our referrals with suspected GCA had CRP&lt;5mg/L but, excluding those with prior PMR, none of these had a positive TAUS or TAB. Therefore with agreement of our department we have now created a referral criteria for TAUS of a pre-steroid CRP&gt;5mg/L (with exceptions possible at consultant discretion). Notably, our laboratory reference range for “normal” is &lt;10mg/L in older patients but we chose to implement this more conservative definition of “normal” for the purposes of GCA diagnosis. Introducing this single TAUS referral criterion has resulted in a noticeable reduction in the number of TAUS required per month. <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