THU0323 THE MANAGEMENT OF BIOPSY NEGATIVE GIANT CELL ARTERITIS BY AUSTRALIAN RHEUMATOLOGISTS

Abstract

Background: The diagnosis of Giant Cell Arteritis (GCA) by Rheumatologists is based on a typical history of headache, jaw claudication and visual disturbance, examination findings such as scalp tenderness and abnormal temporal arteries, and confirmed by temporal artery biopsy (TAB) (1). Temporal artery biopsy is the gold standard for GCA diagnosis (2, 3). However clinicians may diagnose biopsy-negative GCA if there is a high enough pre-test probability for this condition, even if the biopsy is negative. There are few guidelines to assist clinicians with management of biopsy-negative GCA. Objectives: The primary aim of this research project was to determine if there were differences in the management of patients with biopsy-positive versus biopsy-negative GCA with respect to duration of corticosteroid (CS) use, relapse rates, and use of steroid-sparing agents over a 12-month follow-up period in an Australian cohort. We also sought to determine if there were differences in patient characteristics, examination findings and investigation results between the two groups. Methods: All patients who underwent a temporal artery biopsy during 2013-2016 for suspected GCA at three geographic sites (Prince of Wales Hospital, Royal Prince Alfred Hospital and Mid-North Coast Arthritis Clinic, Coffs Harbour) had their files reviewed for clinical presentation, examination findings, investigation results, and management over the 12-months following presentation. Comparison was made between biopsy-positive and biopsy-negative patients. Results: One hundred and forty-two patient files were reviewed. One hundred and one patients were excluded. Of those remaining, 23 were biopsy-positive and 18 were biopsy-negative GCA. Biopsy-negative patients were younger at presentation compared to biopsy-positive GCA patients (69.3 years vs 76.1 years, p = 0.01). There was no difference in the frequency of headache, jaw claudication, polymyalgia rheumatica symptoms or visual disturbance between the two groups of patients. There was also no difference in ESR, CRP, platelet count, total WCC, ALP or Hb level. However, there was a trend towards higher ALP levels in biopsy-positive patients (p = 0.058). The length of temporal artery biopsy was similar between biopsy-positive and biopsy-negative patients (19.4mm vs 19.7mm, p = 0.902). Fewer biopsy-negative patients remained on corticosteroids at 12 months following presentation (65% vs 100%) and of those that did remain on corticosteroids, their dosage tended to be lower than for those with positive biopsies (3.4mg/d vs 7.5mg/d, p = 0.002). Fewer biopsy-negative patients were commenced on methotrexate (5.6% vs 34% p = 0.02). There was no difference in the frequency of relapse between biopsy-positive vs biopsy-negative patients (p = 0.40). Biopsy-positive patients were more likely to present in December or January compared to biopsy-negative patients (p = 0.07). There was no difference in corticosteroid duration prior to biopsy (p = 0.42). Conclusion: Biopsy-positive patients were treated with corticosteroids for longer and at higher doses than those with a negative biopsy. They were also more likely to present in summer and be treated with methotrexate compared to biopsy-negative patients. The seasonal difference in presentation may suggest a different trigger compared to biopsy-negative patients.