The purpose of this study was to examine prevalence trends of serious extra-articular manifestations (EAMs) in a data set representing both hospitalized and ambulatory patients with RA.
This retrospective cohort study used serial cross-sectional data to examine the prevalence of serious EAMs in patients with RA from 1985 to 2006 across the United States (US) Veteran's Health Administration system. Serious EAMs included rheumatoid carditis, RA lung disease, FS and pooled EAM rates included previously reported vasculitis prevalence as queried by ICD-9 searches. Statistical analysis employed auto-regression and time series analysis using the Chow and Durbin-Watson tests to detect breakpoints and linear time-trends.
Among 3 million veterans, including >35,000 RA patients annually, we noted declining RA hospitalizations emphasizing the importance of examining both the inpatient and outpatient settings to assess EAM prevalence. Individual EAM trends varied, demonstrating linear declines in FS, increases in RA lung disease and significant breakpoint declines in carditis and pooled serious EAMs. Pooled EAM prevalence dropped around 2000, from an early linear trend peak of 10% among inpatients, to <7% among both inpatients and outpatients by 2006.
Overall, serious EAMs of RA have declined among US veterans in both the inpatient and outpatient settings, with the exception of RA lung disease likely reflecting improved detection. Breakpoints in pooled EAM prevalence appear to demonstrate consistent, true declines in severe RA extra-articular disease around 2000. Future work should explore the relationship between temporal EAM trends and specific RA therapies including adoption of biological agents.