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

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.