Incidence and mortality rates of biopsy-proven giant cell arteritis in southern Sweden

Objectives To study the epidemiology and mortality in patients with biopsy-proven giant cell arteritis (GCA) in southern Sweden. Methods The study area was the County of Skane. Patients with a positive temporal artery biopsy between 1997 and 2010 were identified using a regional register and a structured review of all histopathology reports. Standardised mortality ratios (SMR) were calculated using data for the Swedish population as the reference. Results There were 840 patients with biopsy-proven GCA (626 women). The annual incidence rate per 100000 inhabitants aged 50years was 14.1 (95% CI 13.1 to 15.0); 7.7 (6.7 to 8.7) for men and 19.6 (18.1 to 21.1) for women, without seasonal variations. The incidence increased with age, with estimates of 2.0, 11.8, and 31.3 per 100000 in the age groups 50-60, 61-70, 71-80years, respectively (p<0.001). The age-standardised and sex-standardised incidence rate decreased from 15.9/100000 in 1997-2001 to 13.3/100000 in 2007-2010 (p=0.026). Two hundred and seventy-nine patients (207 women) died during the observation period. Mortality was significantly increased over the first 2years after GCA diagnosis (SMR 1.52 (95% CI 1.20 to 1.85)), but not with longer follow-up. The estimated excess mortality was greater in women and in patients aged 70years at diagnosis. Conclusions In this large population-based study of biopsy-proven GCA from southern Sweden, the incidence of GCA may have decreased over time. Short-term mortality was increased, in particular among those diagnosed at 70years of age, but long-term survival was not impaired.