Wegener’s granulomatosis and environmental factors in Western Montana

Abstract

The objective of our study was to determine whether exposure to silica or other environmental factors is associated with developing Wegener's granulomatosis (WG), in a geographically isolated region of Western Montana. We sought to identify and interview all cases of WG diagnosed during 1993-2006 among residents of a ten-county region of Western Montana, as well as a group of demographically similar controls (n=39) without autoimmune disease. In the interview, we ascertained occupational silica and other exposures (metals, solvents, pesticides, tobacco). We enumerated 32 cases of WG, of whom 27 were included in the case-control study. Overall, a history of silica exposure was not associated with WG (OR = 0.68, 95% CI: 0.13-3.27), although there was a suggestion of increase in risk among persons with relatively recent (OR=2.67, 95% CI: 0.54-17.2), heavy (OR=1.82, 95% CI: 0.09-112.9), and prolonged (OR=1.53, 95% CI: 0.16-20.0) exposures. A history of having worked in the mining industry was associated with WG (six cases including three with no silica exposure, zero controls, lower 95% CI: 1.53). Risk was not associated with occupational or aerial pesticide exposure, but with residential rodenticide use (OR=12.15, 95% CI: 1.54-552). Occupational exposure to metals or solvents was not associated with WG, nor was a history of cigarette smoking. Results of earlier studies of WG support the hypothesis that silica exposure adversely influences the risk of developing WG. Our small study of WG failed to identify an association with silica overall, but the results are compatible with an increased risk in persons with relatively heavy, prolonged, and/or recent exposure.

The Epidemiology of Antineutrophil Cytoplasmic Autoantibody–Associated Vasculitis in Olmsted County, Minnesota

“…The prevalence of AAV in the present study was also higher than that reported previously in the US and outside the US . The reported prevalence of GPA in other US cohorts includes a report of 3.2 cases per 100,000 population between 1986 and 1990 in New York , and 9.1 cases per 100,000 population between 1993 and 2006 in western Montana , as compared to a prevalence of GPA of 21.8 per 100,000 reported herein. The sole estimation of the prevalence of MPA in the US was reported as being 1.3 cases per 100,000 population , a rate that appears inconsistent with the prevalence of GPA from that same report (which was 7 times higher), and may be a consequence of the methodologic limits of that study (a hospital‐based study).…”

“…The only population‐based analysis of AAV frequency conducted in the US showed that the annual incidence of GPA (adjusted to the US population) was 0.83 cases per 100,000 population (95% confidence interval [95% CI] 0.25–1.42), roughly similar to estimates from northern Europe . Previous epidemiologic studies from the US have demonstrated discrepant prevalence rates for GPA, between 3.2 and 9.1 per 100,000 population . The only published data on mortality in patients with GPA in the US are derived from a non–population‐based study, which reported an annual mortality rate of 0.08 per 100,000 population .…”

“…The only published data on mortality in patients with GPA in the US are derived from a non–population‐based study, which reported an annual mortality rate of 0.08 per 100,000 population . To date, the only available data on mortality in patients with MPA from the US indicated a prevalence of 1.3 per 100,000 population . There are no epidemiologic data on patients with EGPA in the US.…”

ANCA-associated vasculitis

“…There is substantial variation in the relative incidences of GPA and MPA between Europe and Asia, and an effect of latitude. The regions studied include Australia 254 ; Canada 255 ; Germany 256 ; Greece 257 ; Japan 258 ; Lithuania 259 , Turkey 260 ; Peru261 ; Spain (Lugo)262 ; Spain (Malaga)263 ; Sweden 264 ; United Kingdom18 ; USA (Minnesota)2 ; USA (Western Montana)265 ; and the West Bank266 .…”