Aims: To study the epidemiology of biopsy proven giant cell arteritis (GCA) in patients in the Otago region, New Zealand.
Materials and methods: 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.
Results: 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.
Conclusions: 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.