Elevated Rheumatoid Factor Is Associated with Excess Risk for Developing RA

Are people without rheumatoid arthritis (RA) who have elevated blood concentrations of rheumatoid factor (RF) at excess risk for developing RA? Danish investigators attempted to answer this question in this prospective cohort study that involved more than 9700 adults (age range, 20–100) in the general population who underwent blood draws between 1981 and 1983; people with known RA at baseline were excluded.

During follow-up of 28 years, 183 participants developed RA. Risk for RA increased significantly with increasing RF level: Hazard ratios for RA were 3.6, 6.0, and 26 for RF levels of 25 to 50 IU/mL, 50.1 to 100 IU/mL, and >100 IU/mL, respectively, compared with levels of <25 IU/mL. The highest 10-year absolute risk for developing RA (32%)…