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Authors: Wei Sim, Jack Mouhanna, Danah Al-Breiki.

Disclosure Block: W. Sim: None. J. Mouhanna: None. D. Al-Breiki: None.

Abstract Body:

Purpose: Disease relapse in giant cell arteritis (GCA) affects up to two thirds of patients. Few studies have evaluated risk factors for relapse in relation to temporal artery biopsy (TAB) diagnoses, namely biopsy-proven GCA and Healing/Healed arteritis (HH). The significance of HH on TAB is not well understood. The consensus is that HH may be a milder entity when compared to GCA-positive patients. This study examines characteristics of relapse in patients with GCA and HH arteritis on TAB.
Study Design: Retrospective chart-review
Methods: Patients with biopsy-proven GCA or HH at a single tertiary care center (2009-2018) were retrospectively reviewed (n=506: 326 negative, 83 HH and 97 GCA). Relapse was defined as a recurrence of symptoms or signs of GCA and/or an unexplained increase in inflammatory biomarkers.
Results: Seventy-one patients with biopsy-proven GCA and 65 with HH had at least 12 months of follow-up. Scalp tenderness (p=0.033), jaw claudication (p<0.001) and constitutional symptoms (p=0.008) were more common presentations in patients with GCA compared to HH. Both groups had a similar relapse rate of 21% (p=0.23). Patients with HH tended to recur earlier (8 months) compared to GCA (18 months; p=0.068) and at a lower steroid dose (7mg vs 21mg; p=0.043), perhaps owing to a more rapid steroid taper in HH. Within the HH group, those with polymyalgia rheumatica were more likely to have a relapse (p=0.088). In patients who had a relapse, higher baseline levels of ESR (p=0.088) and CRP (p=0.055) were associated with earlier relapse in GCA while lower platelet count was associated with earlier relapse in HH (p=0.025). Finally, large-vessel vasculitis was associated with relapse in GCA (p=0.019) and HH (p=0.026).
Conclusions: Biopsy-proven GCA and HH arteritis may fall under the same clinical spectrum but may differ in their risk factors for relapse. More studies are required to understand how these entities are related to each other.