Page 90 - The Vasculitides, Volume 1: General Considerations and Systemic Vasculitis

66 David S. Younger

in which both environmental and genetic factors contribute to the predisposition and clinical
phenotype. With an incidence and prevalence of primary systemic vasculitis that is steadily
increasing, and an impact that is being reported worldwide in developed countries,
governments, non-governmental organizations, and other key stakeholders have not
developed sufficient programs for the prevention and surveillance of these disorders.

This chapter focuses on the epidemiology of the major large-, medium- and small-size
vessel vasculitides shown in Table 1. There is a recent review of the epidemiology and
classification of primary systemic vasculitides [1].

Large-Size Vessel Vasculitis

Giant Cell Arteritis

Background
Giant-cell arteritis is a chronic granulomatous vasculitis of large and medium-sized

vessels that frequently affected the thoracic aorta and its branches, with a mean age of
diagnosis of age 76 years, and a male to female ratio of 1.5:1 [2]. Both GCA and PMR, a
related disorder, are both probably polygenic disease in which multiple environmental and
genetic factors influence susceptibility and severity [3]. For both the purpose of
epidemiological studies and in clinical practice, GCA has been classified according to the
1990 ACR criteria [4] designed to discriminate between different types of vasculitides.
The five discriminatory features that included age greater than 50 years at onset, new onset of
localized headache, temporal artery tenderness or decreased temporal artery pulse, ESR >50
mm/hour, and biopsy including an artery showing necrotizing arteritis, characterized by a
predominance of mononuclear cells or a granulomatous process with multinucleated giant
cells. Unrecognized and therefore untreated or inadequately treated, there is a high likelihood
of large artery complications including increased morbidity and mortality [5] especially due
to aortic aneurysm and dissection, and large-artery stenosis.

The epidemiology of giant cell arteritis (GCA) was reviewed by Gonzalez-Gay and
colleagues [6]. Since 2000, relatively large cohort studies exemplifying the epidemiological
aspects of GCA in different regions of the world were reported from Australia [7, 8],
Germany [9], Israel [10], Japan [11], New Zealand [12], Norway [13, 14], Spain [15, 16],
Sweden [17], the United Kingdom [18] and the United States [19]. Smaller
non-epidemiological case series of patients with GCA have been reported in Brazil [20],
Saudi Arabia [21], Mexico [22] and Japan [23] where the incidence is very low, especially in
the latter country where nationwide survey of GCA was untaken demonstrated a
correspondingly low prevalence of 1.47 cases per 100,000 population.

Epidemiology
The global incidence and prevalence of GCA is summarized in Table 2.

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