Limited utility of novel serological biomarkers in patients newly suspected of having giant cell arteritis.

Abstract

Diagnosing and monitoring vascular activity in giant cell arteritis (GCA) is difficult due to the paucity of specific serological biomarkers. We assessed the utility of 8 novel biomarkers in an inception cohort of newly suspected GCA patients. Consecutive patients were enrolled between May 2016 and December 2017. Serum was collected within 72hours of commencing corticosteroids and at 6months. It was analyzed for levels of intra-cellular adhesion molecule 1, vascular endothelial growth factor (VEGF), pentraxin 3, von Willebrand factor and procalcitonin (5-plex R&D Systems multiplex assay) and interleukin (IL)6, IL12 and interferon-γ (high-sensitivity 3-plex ProcartaPlex multiplex assay). A GCA specific positron emission tomography / computed tomography (PET/CT) scan was performed at enrolment with uptake in each vascular territory graded and summed to derive a total vascular score (TVS). For the 63 patients enrolled, 12 (19%) had a final diagnosis of biopsy-positive GCA and a further 9 had a clinical diagnosis of biopsy-negative GCA. None of the 8 biomarkers was significantly higher in GCA patients compared with those with alternative diagnoses, or demonstrated a positive correlation with the PET/CT TVS. This was in contrast to the C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) which were higher in the biopsy-positive GCA cohort (P<.04) and showed weak positive correlations with the TVS (correlation coefficient 0.34, P<.01). Procalcitonin did not distinguish between GCA and infection. Concentrations of CRP, ESR, VEGF and pentraxin 3 decreased between diagnosis and 6months in GCA patients. This study did not identify new serological biomarkers to assist in diagnosing or assessing the vasculitis burden in GCA.