Pos0415 Sonographic Prevalence and Characteristics of Subclinical Giant Cell Arteritis in New Onset Polymyalgia Rheumatica

Background: Giant cell arteritis (GCA) and Polymyalgia rheumatica (PMR) are closely linked inflammatory disorders that almost always occur in people older than age 50. Both diseases share similar genetic and acute-phase response patterns. Both GCA and PMR are associated with high financial burden attributed to development of complications, worsening of associated comorbidities, and the number of incident cases is expected to grow as a result of the ageing population. Objectives: 1.To evaluate the prevalence and characteristics of subclinical GCA in patients recently diagnosed to have PMR. 2.To assess whether the presence of subclinical GCA will have a predicting impact on the clinical PMR outcomes and management. Methods: Consecutive recently diagnosed PMR patients were asked to complete a copy of the GCA-specific Patient Reported Outcome Measures (GCA-PROMs) questionnaire 1. In addition to clinical assessment for cranial and extra-cranial vascular affection and recording of baseline covariates; vascular ultrasound (US) assessment of the superficial temporal artery, its frontal and parietal branches as well as the Axillary artery, both sides, was carried out for all the PMR patients at the time of the diagnosis. Sonographic abnormalities which were considered indicative of vasculitis in the temporal arteries include: presence of halo sign and non-compressible arteries. Thickening of the intima-media thickness (IMT) of 0.42mm or more for the common superficial temporal branch, 0.29mm for the parietal branch and 0.34mm for the frontal branch. For the axillary arteries, a halo sign, and an intima-media thickness of >1.0mm were considered positive. Clinical, ultrasound and laboratory characteristics will be recorded at baseline, 1 month and 3 months. Control group: the pattern of vessel involvement will be compared to that of a classical GCA cohort diagnosed according to the ACR/EULAR criteria. Intra- and Inter-observer reliability of the US scanning was carried out. Analysis: The clinical, demographic and laboratory characteristics of the PMR with subclinical GCA cohort were compared to those of PMR as well as GCA only groups. Also, the relation between the presence of subclinical GCA in association with PMR at baseline and the management outcomes was assessed. Results: 108 patients with a new clinical diagnosis of PMR and 110 patients with a recent diagnosis of GCA were included in the study. 23/108 (21.3%) of the PMR patients had evidence of subclinical GCA on ultrasound of their temporal and axillary vessels. There was no significant difference in the measurement of intima media thickness of the temporal and axillary arteries between subclinical GCA in association with PMR and GCA only patient groups, though there was tendency to be less in the subclinical group. The mean initial prednisolone dose initiated for PMR patients was 20.1mg, including those with subclinical GCA symptoms. The mean initial prednisolone dose initiated for GCA patients was 55.5mg of prednisolone. The mean cumulative corticosteroid dose at 3 months for only PMR was 1323.9mg ± 206.2mg, 2164.8mg ± 322.4mg for subclinical GCA in PMR and 2511.2 ± 357.9 in only GCA. At 1- and 3-months follow up monitoring, the presence of subclinical GCA in association with PMR symptoms was associated with significantly higher cumulative glucocorticoids dose than that with pure PMR (p=0.001). Relapse was significantly more common in PMR patients with subclinical GCA (pConclusion: The presence of subclinical GCA in PMR at baseline predicts higher cumulative glucocorticoids dose at three months compared with PMR only. Patients with subclinical GCA in PMR are also more likely to have a clinical relapse in the first three months of treatment than those with either PMR or GCA only. REFERENCES: 1 El Miedany Y et al. Development of GCA PROMs. Semin Arthritis Rheum 2023; 63:152285. Acknowledgements: NIL. Disclosure of Interests: None declared.