The epidemiology of the primary systemic vasculitides in northwest Spain: Implications of the Chapel Hill Consensus Conference definitions

Abstract

OBJECTIVE: To assess the epidemiology of the primary systemic vasculitides (PSV) in a well-defined population of southern Europe over a 14-year period using the Chapel Hill Consensus Conference (CHCC) definitions. METHODS: The case records of all patients 15 years or older with vasculitis diagnosed between January 1988 and December 2001 at a single reference hospital in the Lugo region of northwest Spain were reviewed. Incidence rates were age- and sex-adjusted to the European standard population. Patients were classified as having PSV according to the CHCC definitions. RESULTS: Fifty-four Lugo residents (29 men) fulfilled the CHCC definitions for PSV. The mean age was 60.7 +/- 13.5 years (men: 61.0 +/- 13.4; women: 60.4 +/- 13.8 years). The overall annual incidence of PSV was 13.07/million (95% confidence interval [95% CI] 8.89-19.22). PSV were slightly more common in men. The age-specific incidence showed a clear increase with age. A peak in the 55-64 year age group for the whole group of patients with PSV was observed (34.9/million; 95% CI 28.6-42.6). Nonrandom periodical peaks of incidence every 3 years were only observed when the group of PSV was considered as a whole (P = 0.040). The annual incidence was 2.95/million (95% CI 1.44-6.05) for Wegener's granulomatosis (WG) and 7.91/million (95% CI 4.74-13.20) for microscopic polyangiitis (MPA) (P = 0.035). None of the patients with Churg Strauss syndrome (n = 4) lived in a rural area. CONCLUSION: Our observations support an increasing incidence of PSV with age. In patients from northwest Spain defined by the CHCC definitions, MPA is more common than WG.