THU0313 DISEASE PATTERN AND TIME TO DIAGNOSIS IN A FAST-TRACK GIANT CELL ARTERITIS CLINIC USING ULTRASOUND AS PRIMARY DIAGNOSTIC TOOL

Abstract

Background:Giant Cell Arteritis (GCA) is a vasculitis predominantly affecting the large vessels from aorta and its proximal branches and extra-cranial arteries. Precise and fast diagnosis is important in order to initiate proper treatment and avoid ischaemic events, e.g. irreversible visual loss. Unnecessary and prolonged glucocorticoid treatment is also unwanted due to its significant side effects. Therefore, immediate diagnosis of GCA is recommended, and the primary diagnostic tool, according to EULAR recommendation, is vascular ultrasound (US)1. In 2018, a GCA Fast-Track Clinic (FTC) was implemented in our department covering a population of approximately 900.000. Patients even with a low á-priori suspicion of GCA were accepted. It is the aim to have patients seen within one office day.Objectives:In this retrospective study, to describe clinical data from patients seen in the FTC in a 1-year period from September 1st, 2018 and to investigate the time required for making a diagnosis, and to which extent US as the primary diagnostic tool was adequate for making the final diagnosis.Methods:All patients, irrespective of clinical presentation, had US of bilateral temporal-, facial-, axillary and common carotid arteries done (exam time 30 min.). All US were done by ultrasonographers with experience and training in vascular US. Immediately after the initial US, patients were seen by a senior registrar in rheumatology at our out-patient clinic. The senior registrar was aware of the conclusion of the US. Decisions on further diagnostic procedures were solely up to this rheumatologist. From electronic patient report files, all patients’ clinical- and US-findings as well as results from other diagnostic procedures (temporal artery biopsy (TAB) and positron emission tomography computed tomography (PET-CT)) were evaluated. Furthermore, final diagnosis and fulfilment of ACR1990 classification criteria for temporal arteritis at three months was noted, as was the number of days required for diagnosis.Results:A total of 120 patients were seen in the FTC and had a vascular US done. Demographic and clinical data are seen in table 1. Of 120 patients, 42 (35%) had a clinical diagnosis of GCA at three months and 42% fulfilled ACR1990 criteria for temporal arteritis. Based on US alone, 36% of patients had GCA. A diagnosis or exclusion of GCA were done on median 1 day (in 55% of patients). However, in cases where further diagnostics (TAB and PET-CT) were necessary, the time for diagnosis increased substantially. See table 2 for data on waiting time from referral, diagnoses and time required for diagnosis.Table 1Demographic and clinical data (n=120)Females72%Age (years)74 (46-98)Symptom duration (days)16 (1-180)New onset headache72%Jaw claudication21%Temporal artery abnormality33%Visual symptoms42%Visual loss (permanent visual loss)18% (19%)Constitutional symptoms32%Fever11%Weight loss18%Polymyalgia symptoms33%Glucocorticoid therapy68%Duration of glucocorticoid (days)3 (1->365)Haemoglobin (mmol/L)8.0 (5.0-10.0)C-reactive protein (mg/L)22 (0-290)Sedimentation rate (mm/hr)38 (2-146)Values are percentage, median (range)Table 2Office days from referral to visit1 (0-20)Days for diagnosis/exclusion of GCA1 (1-46)GCA clinical diagnosis35%GCA ACR1990 criteria42%Nr. of US (% w. GCA)120 (36%)Nr. of PET-CT (% w. GCA)44 (23%)Nr. of TAB (% w. GCA)34 (21%)Polymyalgia diagnosis17%Arthritis diagnosis5%Other diagnosis17%Conclusion:In this newly established GCA FTC, fast and precise diagnosis of GCA or exclusion of this was possible in majority of patients referred, even though referral criteria were liberal. In 55% of patients, further diagnostic procedures were considered unnecessary, and a diagnosis on day 1 could be established based on US, clinical findings and existing paraclinical data.