Background Giant cell arteritis (GCA) is the most common type of vasculitis which occurs especially in women who are older than 70 years of age and of northern European origin. Magnetic resonance angiogram (MRA), computed tomography angiogram (CTA) and positron emission tomography (PET) are being increasingly used as non-invasive tools to diagnose extracranial involvement of the large vessels in patients with suspected GCA.
Objectives We aimed at updating the incidence of GCA in the current era of advanced diagnostic imaging, 2005-2009 compared to 2000-2004.
Methods Using the resources of Rochester Epidemiology Project (REP), incident cases of GCA in Olmsted County, Minnesota, USA between January 1, 2005 and December 31, 2009 was identified and compared to the incident cases between January 1, 2000 and December 31, 2004 in the same population. GCA was defined according to the 1990 American College of Rheumatology (ACR) classification criteria and a physician diagnosis. Patients greater than 50 years of age with elevation of erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) and CTA, MRA or PET scan evidence of large vessel vasculitis involving the ascending aorta and/or its branches were also included. Asymptomatic patients with incidental finding of aortitis in pathology status-post aortic aneurysm repair or aortic valve replacement were not included. Incidence of GCA per 100,000 population was calculated after adjusting for age and sex to the 1980 US white population aged greater than or equal to 50 years.
Results We identified 39 patients with GCA in 2005-2009 and 35 patients in 2000-2004. Mean age of patients was 77.1 years [standard deviation (SD) 8.8] in 2005-2009 cohort and 79.3 years (SD 7.4) in 2000-2004 (p=0.28). Majority of the patients were women: 77% in 2005-2009 and 83% in 2000-2004 (p=0.53). Temporal artery biopsy was positive in 28 of 39 patients (76%) in 2005-2009 and in 28 of 35 (82%) in 2000-2004 (p=0.49). 5 of 11 patients in 2005-2009 cohort and 1 of 7 patients in 2000-2004 cohort with negative temporal artery biopsies were included based on the radiological criteria. Among these 5 patients in 2005-2009 cohort, CTA was used in 2; MRA in 1; PET scan in 2 patients; and MRA was used in the patient in 2000-2004 cohort. The overall age- and sex- adjusted incidence rate in 2005-2009 was 19.5 per 100,000 population [95% confidence interval (CI): 13.2, 25.8]. This is nearly identical to the estimated incidence of GCA in 2000-2004, which was 18.9 per 100,000 (95% CI: 12.4, 25.5).
Conclusions Imaging techniques such as CTA, MRA and PET are more commonly used in the recent years for diagnosing GCA involving the ascending aorta and/or its major branches in suspected patients with negative temporal artery biopsy. The overall incidence of GCA has not changed significantly in the recent years.
Disclosure of Interest: None Declared
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