PREVALENCE OF SUBCLINICAL GIANT CELL ARTERITIS IN PATIENTS WITH POLYMYALGIA RHEUMATICA

BackgroundPolymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are closely related diseases. PMR occurs in approximately 50 % of patients with GCA1; however the prevalence of subclinical GCA in PMR has not yet been widely studied.ObjectivesThe aim of our multicenter, prospective study was to determine the prevalence of subclinical GCA in newly diagnosed PMR, using vascular ultrasound (US) as a diagnostic tool.MethodsEight European centers participated in the study. The studied cohort represented consecutive newly diagnosed patients with PMR who fulfilled 2012 EULAR/ACR Provisional Classification Criteria for Polymyalgia Rheumatica2 without symptoms or signs suggestive for GCA. All patients underwent ultrasound (US) of both hips and shoulders, as well as of four bilateral arterial territories (i.e. temporal, common carotid, subclavian and axillary arteries). Patients with positive halo signs were considered to have subclinical GCA 3. An intima-media thickness ≥0.34 mm for frontal and parietal TA, 0.42mm for common TA, and ≥1 mm for common carotid, axillary and subclavian arteries for positive result. Clinical demographic and laboratory characteristics of the PMR pure group were compared with the PMR/GCA patient group.ResultsA total of 258 patients were included, 137 (53.1%) females with a mean age of 73±8.4 years. Table 1 shows the main differences in PMR patients with and without subclinical GCA. The only statistical significant difference between the two groups was the higher prevalence of morning stiffness > 40 minutes in the pure PMR group (p<0.05). A halo sign was found on at least one of the examined arteries in 56/258 patients (21.7%).The different subtypes of vessel involvement were available in 216 cases. Data compatible with the diagnosis of GCA was found in 41 cases (19%): 10 (24.3%) had only temporal artery involvement (“cranial” GCA), 27 (65.8%) had an extra-cranial artery involvement and 4 (9.8%) a mixed form with both cranial and extra-cranial artery involvement (Figure 1).Table 1.Clinical and demographic characteristicsFigure 1.Subtypes of subclinical GCA in PMR in 216 patients with cranial and extra-cranial examinationConclusionOne fifth of PMR patients without symptoms or signs of GCA have ultrasound findings consistent with the diagnosis of GCA. Subclinical GCA in PMR shows a predilection for extra-cranial artery involvement.References[1]Buttgereit F et al. JAMA. 2016;315:2442-58.[2]Dasgupta B et al. Arthritis & Rheumatism. 2012; 64:943–954.[3]De Miguel E et al. Rheumatology 2018; 57:318-321.AcknowledgementsTo the GCA/PMR study groupDisclosure of InterestsNone declared