The epidemiology of giant cell arteritis in Otago, New Zealand: a 9-year analysis

To study the epidemiology of biopsy proven giant cell arteritis (GCA) in patients in the Otago region, New Zealand.

Records of 363 consecutive patients who underwent temporal artery biopsy at Dunedin Hospital between 1996–2005 were reviewed. Annual incidence of biopsy-proven GCA was estimated, epidemiologic characteristics of the biopsy-positive group was compared with the biopsy-negative group.

Among the 363 patients who underwent temporal artery biopsy there were 105 (29%) males and 258 (71%) females; biopsy-proven GCA was diagnosed in 70 (19%) patients. The mean age of biopsy-positive group was 72.8 years (range 57-91 years, SD 8.2), which was comparable to the biopsy-negative group 73.4 years (range 50–97 years, SD 9.5), p<0.2. The mean annual incidence of GCA in Otago was 12.73/100,000 CI (11.7–14.3, p<0.5) for patients ≥50 years over the 9 years of observation.

The first large study of GCA from Australasia demonstrated that a variation in the annual incidence rate for giant cell arteritis in Otago, New Zealand showed a cyclic pattern. The overall incidence seems to reflect the ethnic origins of the majority of the population from Britain.