Incidence of Extraarticular Rheumatoid Arthritis in Olmsted County, Minnesota, in 1995-2007 Versus 1985-1994: A Population-based Study

Objective. To assess incidence and mortality effects of extraarticular rheumatoid arthritis (ExRA) in patients with incident RA in 1995-2007 compared to 1985-1994, in Olmsted County, Minnesota, USA. Methods. Data on incident ExRA were abstracted from medical records of patients with RA Olmsted County residents who first met the 1987 American College of Rheumatology criteria for RA between January 1, 1995, and December 31, 2007. Patients were followed until death, migration from Olmsted County, or December 31, 2008. ExRA were classified using the predefined criteria and compared to the corresponding 1985-1994 inception RA cohort (n = 147). Results. The 1995-2007 cohort included 463 patients with RA followed for a mean of 6.3 years; mean age was 55.6 years, 69% were women, 67% were positive for rheumatoid factor (RF). The 10-year cumulative incidence of any ExRA (50.1%) and severe ExRA (6.7%) in the 1995-2007 cohort was similar to the 1985-1994 cohort (46.2% and 9.7%, respectively). The 10-year cumulative incidence of vasculitis, but not other features of ExRA, was significantly lower in the 1995-2007 cohort (0.6%) compared to the 1985-1994 cohort (3.6%). RF positivity, erosions/destructive changes, and use of methotrexate, other disease-modifying antirheumatic drugs and systemic corticosteroids were significantly associated with ExRA in the 1995-2007 cohort. ExRA was associated with mortality risk (HR 2.1, 95% CI 1.2, 3.7) in the 1995-2007 cohort. The decrease in mortality following ExRA in the 1995-2007 cohort versus the 1985-1994 cohort did not reach statistical significance (HR 0.6,95% Cl 0.3, 1.2, p = 0.16). Conclusion. ExRA remains a common complication associated with increased mortality in RA. The occurrence of vasculitis appears to be decreasing in recent years. (First Release April 1 2011; Rheumatol 2011;38:983-9; doi:10.3899/jrheum.101133)