epidemiology

Last reviewed 05/2021

Temporal arteritis/giant cell arteritis (GCA) almost exclusively affects individuals over 50 years, and is more common in women than men (2.5-3x).

It affects extracranial arteries in 90% of cases. Intracranial arteries are only rarely involved.

Polymyalgia rheumatica (PMR) precedes or accompanies giant cell arteritis in more than 50% of cases.

In the UK both PMR and temporal arteritis were more common in the south than in the north, and both were more commonly diagnosed in the summer months (1). Age adjusted annual incidence of GCA in the UK and the USA is estimated at 18-22/100 000 (2).

• GCA and PMR are common in Caucasians, but rare in Asians and Afro-Carribeans
  • a positive correlation between incidence and increasing latitude
    • incidence has been estimated in over 50s at 7/100 000 of in Italy and 30/100 000 in Denmark
  • may be linked to environmental agents
    • a serological association between Human Para influenza virus and GCA and PMR has been seen in epidemiological studies
      • association was most marked in the biopsy proven cases of GCA
    • a correlation between rates of GCA and the incidence of parvovirus B19 infection has also been shown. Mycoplasma pneumoniae infections show a similar correlation
      • chlamydia pneumoniae has been found in biopsy specimens using immunohistochemistry and PCR
  • non-infective environmental agents have also been linked to development of GCA
    • smoking and arterial disease may be associated, as may be sun exposure in those with skin sensitivity
    • nulliparity and prolonged sun exposure (actinic hypothesis) in genetically predisposed people with skin sensitivity have been described as risk factors
    • relationship with increasing age
      • led to the suggestion that ageing of the immune system leads to failure of tolerance mechanisms, allowing triggering or perpetuation of a maladaptive inflammatory response

Reference:

• (1) Smeeth L, et al. Incidence of diagnosed polymyalgia rheumatica and temporal arteritis in the United Kingdom, 1990-2001. Ann Rheum Dis. 2006;65(8):1093-8.
• (2) Luqmani R. Treatment of polymyalgia rheumatica and giant cell arteritis: are we any further forward? Ann Intern Med.2007;146:674-676
• (3) Penn H, Dasgupta B. Giant cell arteritis. Autoimmunity Reviews 2003; 2 (4):199-203.