Pos0716 differences in clinical and ultrasound characteristics of polymyalgia rheumatica patients with subclinical giant cell arteritis compared to those with clinical giant cell arteritis

Background It has been reported that more than a quarter of patients with polymyalgia rheumatica (PMR) have subclinical giant cell arteritis (GCA) [1]. Risk markers for subclinical GCA in PMR have not been clearly established and it is unclear if the pattern of vascular involvement on ultrasound differs from that seen in GCA. Objectives To identify the characteristics of PMR patients that have subclinical GCA and to compare the ultrasound features of subclinical GCA in PMR to a GCA cohort. Methods 58 newly diagnosed PMR patients who met a clinical diagnosis for PMR were examined with ultrasound of their temporal and axillary arteries at time of diagnosis. US of all 6 branches of the superficial temporal arteries and both axillary arteries was performed using a GE P9 device. Sonographic abnormalities considered indicative of vasculitis in the temporal arteries included the halo sign and non-compressible arteries with a thickened intima-media complex. In the axillary arteries, a halo sign, and an intima-media thickness of >1.0mm was considered positive. Clinical and laboratory characteristics were recorded. Halo scores were calculated for positive cases. Ultrasound findings were compared to a cohort of 57 GCA patients. Results Our cohort consisted of 58 patients with newly diagnosed PMR. The mean age was 68 years and 48% were male and 53% were female. ACR/EULAR classification criteria were met in 46/58 patients (primarily due to prior corticosteroid use in primary care resulting in normal ESR/CRP). 15 patients (25.8%) were identified as having subclinical GCA on ultrasound. Of these, 12 were male and 3 were female (p=0.0201). The mean ESR at baseline for those with isolated PMR was 35, compared to 53 for those with subclinical GCA (p=0.0419). The mean baseline ESR for our GCA cohort was 58. There was no significant difference in the baseline CRP levels, between those with subclinical GCA and isolated PMR (p=0.1150). The extent of involvement of the temporal and axillary arteries of the 58 patients in the subclinical GCA group was compared to a cohort of 57 GCA patients. The total halo count was the similar for both subclinical GCA and clinical GCA at 4.33 and 4.36. However, GCA patients had higher halo scores in both temporal and axillary vessels of 13.17 and 13.28 respectively, compared to those with subclinical GCA with scores of 5 and 9.6. Table 1. Isolated PMR (43) Subclinical GCA (15) GCA (57) Age (mean + range) 67 (50-84) 70 (53-84) 74 (56-92) Female 27 3 24 Male 16 12 33 BMI 28.3 27.9 27.8 Mean ESR at baseline (mm/h) 35 53 58 Mean CRP at baseline (mg/l) 24 40 66 Mean Halo count 0 4.33 4.36 Mean temporal artery halo score 0 5 13.17 Mean axillary artery halo score 0 9.60 13.28 Conclusion PMR patients with subclinical GCA have a similar halo count to patients with clinical GCA suggesting a similar pattern of vascular involvement. However, those with clinical GCA have higher halo scores indicating more advanced vessel oedema which may be a key factor in causing headache symptoms. Male gender and a higher ESR at the time of PMR diagnosis appear to be risk markers for subclinical GCA though this requires analysis in larger cohorts of patients. Reference [1]Hemmig, A.K., et al., Subclinical giant cell arteritis in new onset polymyalgia rheumatica A systematic review and meta-analysis of individual patient data. Semin Arthritis Rheum, 2022. 55 : p. 152017. Acknowledgements: NIL. Disclosure of Interests Sharon Cowley: None declared, Colm Kirby: None declared, Patricia Harkins Grant/research support from: Janssen, Ronan Mullan: None declared, Richard Conway: None declared, Grainne Murphy: None declared, David Kane: None declared.