Session Type: Poster Session (Tuesday)
Session Time: 9:00AM-11:00AM
Background/Purpose: Giant Cell Arteritis (GCA) remains challenging to diagnose as false negative temporal artery biopsy (TAB) can occur. Color doppler ultrasonography (CDUS) of the temporal, axillary and carotid arteries is useful when GCA is suspected. A wide range of sensitivities and specificities of CDUS are reported, with better results when performed by a trained sonographer using high resolution equipment. The new GCA probability score (GCAPS) is intended to risk-stratify patients with suspected GCA into those with high probability versus low probability of GCA. This study aimed to 1) compare CDUS results against TAB with final diagnosis of the specialist as the reference standard; 2) determine how GCAPS performs in relation to the final diagnosis.
Methods: A retrospective chart review was performed for all patients with suspected GCA who had a CDUS from July 2017 to May 2019, at Hopital du Sacre-Coeur de Montreal (University of Montreal). All exams were performed by the same ultrasonographer with the Zonare Z One Ultra Ultrasound SystemTM using a linear array probe (L14-5Mhz). Data collected included patient characteristics, clinical presentation, physical examination, bloodwork, initial clinical suspicion of GCA (low or moderate/high) and CDUS results of the temporal, carotid and axillary arteries. TAB results and final diagnosis as determined by the treating physician were documented. GCAPS was retrospectively calculated if all the required items were available.
Results: A total of 56 patients had a CDUS examination during the specified time period; amongst them, 31 patients had a TAB. GCA was the final diagnosis in 20 patients, as determined by the treating specialist. Sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) were 95.0%, 100%, 100%, 97.3% for CDUS; and 81.3%, 100%, 100%, 83.3% for TAB, respectively. There were no false positive CDUS in patients without GCA. Only 1 patient with GCA had a negative CDUS while the TAB was positive. A false negative TAB was observed in 3 patients with GCA, all of which had a positive CDUS. In those 3 patients with negative TAB and positive CDUS, one had extra-cranial large-vessel vasculitis on PET/CT, the second had abnormal temporal arteries on physical examination (tenderness and pulselessness) and the third had classic cranial symptoms of GCA with thrombocytosis and elevated inflammatory markers. False negative rate of CDUS was 5% as opposed to 18.7% for TAB.
GCAPS score of < 9.5 points was found in 1 patient with GCA and 21 patients without GCA. At a cut-off value of 9.5 points, Se, Sp, PPV and NPV for the GCAPS were 95.0%, 65.6%, 69.3% and 95.5% respectively. In our cohort, GCA was the final diagnosis for all patients with a GCAPS ≥ 13 points.
Conclusion: CDUS of the temporal, carotid and axillary arteries showed a high Se and Sp and helped to identify TAB negative patients with GCA. We validated that the GCAPS is a useful clinical tool in our patient population; a score < 9.5 points makes the diagnosis of GCA unlikely.
To cite this abstract in AMA style:Makhzoum J, Belhocine M, Goulet M, Rheaume M, Starnino T, Ducharme-Benard S, Febrer G, Troyanov Y, Routhier N, Meunier R, Chagnon I, Laurier M, Helou M, Morency N, Mansour A. Color Doppler Ultrasound for the Diagnosis of Giant Cell Arteritis in Montreal: A Canadian Single Center Experience [abstract]. Arthritis Rheumatol. 2019; 71 (suppl 10). https://acrabstracts.org/abstract/color-doppler-ultrasound-for-the-diagnosis-of-giant-cell-arteritis-in-montreal-a-canadian-single-center-experience/. Accessed September 28, 2020.
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