Giant cell arteritis and its mimics: A comparison of three patient cohorts.

OBJECTIVE:To compare temporal artery biopsy (TAB)-positive giant cell arteritis (GCA) to TAB-negative GCA and patients with GCA mimics METHODS: PATIENTS DIAGNOSED WITH TAB-POSITIVE AND TAB-NEGATIVE GCA BETWEEN 1/1/1998 AND 12/31/2013 WERE: retrospectively identified. These two groups were compared to a cohort of patients with TAB performed between 1/1/2009 and 12/31/2010 in which the TAB was negative and alternative diagnosis was provided after a minimum of 6-months of follow-up. Baseline characteristics were compared between groups using chi-square and rank sum tests. RESULTS:591 study subjects were identified (286 TAB-positive, 110 TAB-negative GCA and 195 TAB-negative GCA mimics) during the respective study periods. Compared to TAB-negative GCA, GCA mimics had similar rates of headache and vision loss but significantly less frequent jaw/limb claudication, arterial bruits and constitutional symptoms, as well as lower platelet levels. Compared to TAB-positive GCA patients, TAB-negative GCA were younger, had shorter time to diagnosis, met fewer 1990 ACR classification criteria and had lower frequencies of polymyalgia rheumatica, jaw claudication and temporal artery abnormalities; but, higher frequency of arm claudication and constitutional symptoms. Among 61 TAB-negative patients with advanced arterial imaging, 43 (69%) had at least one abnormality consistent with GCA. CONCLUSION:Consideration of alternative diagnoses is requisite in evaluating patients with negative TAB. Advanced imaging assists in identifying occult large-vessel vasculitis and should be employed in all TAB-negative patients with suspicion for GCA.