Epidemiology of Wegener's granulomatosis in northern Norway

Objective. To determine if changes in the incidence, prevalence, and clinic al presentation of Wegener's granulomatosis (WG) have occurred in the stabl e population of northern Norway during a 15-year period. Methods, We performed a retrospective cohort study using hospital discharge records from all 11 hospitals in the region and the databases of the 2 pat hology departments in the area. Only patients fulfilling the American Colle ge of Rheumatology 1990 criteria for WG were included in the study, and dem ographic and clinical data at diagnosis were recorded. Incidence, point pre valence, and period prevalence rates were estimated for three 5-year period s. Results. Fifty-five patients (62% male) with a median age at diagnosis of 5 0 years (range 10-84 years) fulfilled the inclusion criteria. The annual in cidence/million population increased from 5.2 (95% confidence interval [95% CII 2.7-9.0) during 1984-1988 to 12.0 (95% CI 8.0-17.3) during 1994-1998, The point prevalence/million increased from 30.4 (95% CI 16.6-51.0) to 95.1 (95% CI 69.1-129.0), The highest incidence rate occurred in men ages 65-74 years. There were no significant period differences in age, first organ in volved, delay of diagnosis, or disease activity, but fewer patients had mal aise and renal insufficiency during the earliest time period. No seasonal v ariation in the onset of WG was present, although we noted a pattern of ann ual fluctuation. Conclusion. The prevalence of WG has tripled in northern Norway over the la st 15 years, While more efficacious therapy may explain part of this increa se, we also found a significant trend toward increased incidence over that period, The incidence rate over the last 5 years is the highest reported so far, while the clinical presentation has remained unchanged.