Decline in rheumatoid vasculitis prevalence among US veterans: a retrospective cross-sectional study.

OBJECTIVE: To examine trends in the prevalence of rheumatoid vasculitis in a national US population comprising both hospitalized and ambulatory patients with rheumatoid arthritis (RA).
METHODS: In this serial cross-sectional study, we analyzed data on hospitalized and ambulatory patients spanning 22 years (1985-2006) and 10 years (1997-2006), respectively, to determine the prevalence of rheumatoid vasculitis, as defined by the International Classification of Diseases, Ninth Revision. Our search encompassed data collected on a predominantly male study population during 10 million hospitalizations and outpatient visits, and included annual data on >37,000 RA patients. To test for a decrease in rheumatoid vasculitis prevalence, breakpoint analysis was performed using stepwise Chow and Durbin-Watson tests.
RESULTS: There was a clear decline in the prevalence of rheumatoid vasculitis, and this decline remained evident even after accounting for a decreased number of hospitalizations among RA patients. Peak prevalence occurred among hospitalized patients in the 1980s, and prevalence gradually declined throughout the 1990s. Furthermore, simultaneous breakpoints representing a significant drop in rheumatoid vasculitis prevalence between the years 2000 and 2001 were demonstrated for both inpatients (P < 0.000) and outpatients (P < 0.003). The prevalence of vasculitis dropped 53% among inpatients and 31% among outpatients between 2000 and 2001.
CONCLUSION: Our results demonstrate a significant decline in rheumatoid vasculitis prevalence after 2000 in this nationwide sample of hospitalized and ambulatory patients. The clear, consistent drop in prevalence provides an opportunity for the formulation of causal hypotheses, including consideration of the impact of biologic agents used to treat RA, on rheumatoid vasculitis.