Incidence of leukocytoclastic vasculitis, 1996 to 2010: a population-based study in Olmsted County, Minnesota.

OBJECTIVE: To determine the population-based incidence of leukocytoclastic vasculitis (LCV).

PATIENTS AND METHODS: This is a retrospective population-based study of all Olmsted County, Minnesota, residents with a skin biopsy-proven diagnosis of LCV from January 1, 1996, through December 31, 2010.

RESULTS: A total of 84 patients (mean age at diagnosis, 48.3 years) with newly diagnosed skin biopsy-proven LCV (43 women and 41 men) were identified. The incidence rate (age and sex adjusted to the 2000 US white population) was 4.5 per 100,000 person-years (95% CI, 3.5-5.4). The incidence of LCV increased significantly with age at diagnosis (P<.001) and did not differ between female and male patients. Subtypes of LCV were cutaneous small-vessel vasculitis (CSVV), 38 patients (45%); IgA vasculitis, 25 (30%); urticarial vasculitis, 10 (12%); cryoglobulinemic vasculitis, 3 (4%); and antineutrophil cytoplasmic antibody-associated vasculitis, 8 (10%). LCV was idiopathic in 29 of 38 patients with CSVV (76%) and 24 of 25 patients with IgA vasculitis (96%). Thirty-nine of 84 patients (46%) had systemic involvement, with the renal system most commonly involved (17 of 39 [44%]). Twenty-four of 80 patients (30%) with follow-up data available had recurrent disease. Compared with the Minnesota white population, observed survival in the incident LCV cohort was significantly poorer than expected (P<.001), including the subset of patients with idiopathic CSVV (P=.03).

CONCLUSION: The incidence of LCV was higher than that reported in previously published studies. Idiopathic LCV was more common in our population-based cohort than that described previously. Overall survival was significantly poorer (P<.001) and should be explored further in future studies.