Introduction Giant cell arteritis (GCA) is a common large vessel vasculitis in those over age 50 years. This meta-analysis examined the geographical and temporal distribution of the incidence, prevalence, and mortality of GCA. Methods A systematic review was conducted using EMBASE, Scopus, and PubMed from their inceptions until 2019. Studies were included if they reported at least 50 or more GCA patients and defined the location and time frame. Articles on mortality were included and standardized mortality ratio (SMR) was extracted where possible. Mean pooled prevalence, incidence, and SMR were calculated using a random effects model. Linear regression was used to explore correlations between latitude and incidence, prevalence, and mortality. Results Of the 3569 citations identified, 107 were included. The pooled incidence of GCA was 10.00 [9.22, 10.78] cases per 100,000 people over 50 years old. This incidence was highest in Scandinavia 21.57 [18.90, 24.23], followed by North and South America 10.89 [8.78, 13.00], Europe 7.26 [6.05, 8.47], and Oceania 7.85 [− 1.48, 17.19]. Pooled prevalence was 51.74 [42.04, 61.43] cases per 100,000 people over age 50. Annual mortality was 20.44 [17.84, 23.03] deaths/1000. Mortality generally decreased over the years of publication (p = 0.0008). Latitude correlated significantly with incidence (p = 0.0011), but not with prevalence, or mortality. Conclusions GCA incidence varies nearly 3-fold between regions and is highest in Scandinavia but not significantly. Mortality may be improving over time.

Background:Giant cell arteritis (GCA) is an immune-mediated disease of the large vessels, and occurs in adults over 50 years old1. It is the most commonly seen form of chronic vasculitis and is associated with significant rates of morbidity2. This meta-analysis examines the geographical and temporal epidemiology of GCA, including incidence, prevalence and mortality.Objectives:To identify changes in incidence rate, prevalence, and mortality rate over timeTo compare these rates between geographic regions around the worldMethods:A systematic review of the English literature was conducted using the EMBase, Scopus and PubMed databases. Articles were included if they were cohort or cross-sectional studies with 50 or more patients with GCA and reported on population, location and time-frame parameters. Articles on mortality were included if they compared mortality to age and gender matched population. Review articles, case-control studies and case series were excluded. Two reviewers extracted data and a third verified inclusion of studies. Study quality was assessed by using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. Mortality rate was standardized across cohorts to deaths per 1000 people per year.Results:Of the 3569 citations identified by the literature search, 107 were included in analysis. The pooled incidence of GCA internationally was 10.00 [9.22, 10.78] cases per 100 000 people over 50 years old (Figure). This incidence was highest in Scandinavia 21.57 [18.90, 24.23], followed by North and South America 10.89 [8.78, 13.00], Europe 7.26 [6.05, 8.47], and Oceania 7.85 [1.48,17.19]. Nine studies reported prevalence. Pooled prevalence from these 9 was 51.74 [42.04,61.43] cases per 100 000 people over 50 years old. Overall, pooled mortality was 20.44 [17.84,23.03] deaths/1000 per year. Mortality had a generally decreasing trend over the years of publication.Conclusion:The incidence of GCA varies regionally almost 3-fold. Likely genetic and environmental factors may explain this trend. Incidence and prevalence are important for tracking the efficacy and side effects of current therapies, as well as planning for the costs of biologic treatment.References:[1] Floris A, Piga M, Cauli A, Salvarani C, Mathieu A. Polymyalgia rheumatica: an autoinflammatory disorder?. RMD Open. 2018;4(1):e000694. Published 2018 Jun 4. doi:10.1136/rmdopen-2018-000694[2] Crow RW, Katz BJ, Warner JE, et al. Giant cell arteritis and mortality. J Gerontol A Biol Sci Med Sci. 2009;64(3):365–369. doi:10.1093/gero na/gln030Acknowledgments:Both Daniel Semenov and Katherine Li equally contributed and sharing first authorshipFunding in part was from the Canadian Rheumatology Association summer studentshipDisclosure of Interests:Daniel Semenov: None declared, Katherine Li: None declared, Matthew Turk: None declared, Janet Pope Grant/research support from: AbbVie, Bristol-Myers Squibb, Eli Lilly & Company, Merck, Roche, Seattle Genetics, UCB, Consultant of: AbbVie, Actelion, Amgen, Bayer, Boehringer Ingelheim, Bristol-Myers Squibb, Eicos Sciences, Eli Lilly & Company, Emerald, Gilead Sciences, Inc., Janssen, Merck, Novartis, Pfizer, Roche, Sandoz, Sanofi, UCB, Speakers bureau: UCB