SAT0271 The Impact of Clinical Features and Corticosteroids on Biopsy Findings in GIANT Cell Arteritis
Authors: K. Jakobsson, L. Jacobsson, A.J. Mohammad, J.-Å. Nilsson, K.J. Warrington, E.L. Matteson, C. Turesson
Journal: Annals of the Rheumatic Diseases (2014)

<h3>Background</h3> Temporal artery biopsy (TAB) is often used to confirm or reject the diagnosis both in uncertain cases and when the clinical picture indicates giant cell arteritis (GCA). There are conflicting data on the impact of corticosteroid treatment on TAB findings in patients with GCA. <h3>Objectives</h3> To investigate the impact of baseline clinical characteristics and corticosteroid treatment on TAB findings in patients with GCA. <h3>Methods</h3> Individuals who developed GCA after inclusion in two population-based health surveys were identified by linking the health survey databases to the local patient administrative register and the national patient register. In addition, other patients diagnosed with GCA at the Departments of Internal Medicine and Rheumatology at a hospital in the area during the same period were also included. A structured review of medical records and TAB pathology reports was performed. The presence or absence of giant cells, granuloma, fragmented internal elastic lamina, fibrosis and grade of inflammatory infiltrates were recorded. The relationships between reported histopathologic features, time from treatment start to TAB and clinical parameters was investigated. <h3>Results</h3> In 183 included cases with a confirmed clinical diagnosis of GCA, the median time from start of corticosteroid treatment to TAB was 2 days [interquartile range (IQR) 1-4; total range -22 to 253]. The proportions with a positive biopsy in relation to timing of biopsy in relation to treatment start did not differ significantly; 86% (0 days), 69% (1-3 days), 79% (4-7 days) and 80% (8-28 days) (p=0.17). Patients with a positive biopsy (77%) had significantly higher CRP (p=0.007) and ESR (p=0.03) at the time of clinical diagnosis. In logistic regression analysis, comparing biopsies performed before or on the same day as initial treatment to those 1-3 days after treatment start, the former was associated with a positive biopsy (OR 2.86; CI 1.06-7.70) and occurrence of inflammatory infiltrates (OR 3.74; CI 1.31-10.71). Minor inflammatory infiltrates were still seen, although less frequently, among those with longer time on corticosteroid treatment prior to TAB (p for trend: 0.03), whereas there was no such trend for major inflammatory infiltrates. The proportions with other histopathology features did not differ significantly across categories of time on corticosteroids. Patients with pre-treatment biopsy had lower ESR levels (p=0.04) and were less likely to have visual symptoms at diagnosis (36% vs 54%; p=0.04). <h3>Conclusions</h3> Biopsies were more likely to be positive and have characteristic histopathologic features in patients with high CRP and ESR, and prior to start of corticosteroid treatment, whereas a TAB performed a week or more after initiation of therapy still yields clinically useful information for the diagnosis of GCA. <h3>Disclosure of Interest</h3> None declared <h3>DOI</h3> 10.1136/annrheumdis-2014-eular.2362