Elevated Rheumatoid Factor Ups Risk of Developing RA
Individuals without RA but with rheumatoid factor levels >100 IU/mL have a 26-fold increased risk
FRIDAY, Sept. 7 (HealthDay News) -- Individuals in the general population with elevated levels of rheumatoid factor have a significantly increased risk of developing rheumatoid arthritis, according to a study published online Sept. 6 in BMJ.
Sune F. Nielsen, Ph.D., from the Copenhagen University Hospital in Denmark, and colleagues conducted a prospective cohort study involving 9,712 white Danish individuals in the Copenhagen general population, aged 20 to 100 years, to examine whether elevated concentration of rheumatoid factor correlates with long-term development of rheumatoid arthritis.
The researchers found that 183 individuals developed rheumatoid arthritis during 187,659 person-years. A doubling in levels of rheumatoid factor in healthy individuals correlated with a 3.3-fold increase in the risk of developing rheumatoid arthritis, with a similar trend noted for most other autoimmune rheumatic diseases. With increasing rheumatoid factor category the cumulative incidence of rheumatoid arthritis increased. Compared with a rheumatoid factor level of <25 IU/mL, the multivariable adjusted hazard ratio was 3.6 for levels of 25 to 50 IU/mL; 6.0 for 50.1 to 100 IU/mL; and 26 for >100 IU/mL. Fifty- to 69-year-old women who smoked and had rheumatoid factor levels above 100 IU/mL had the highest absolute 10-year risk of rheumatoid arthritis (32 percent).
"Individuals in the general population without rheumatoid arthritis but with an elevated plasma level of rheumatoid factor have up to 26-fold greater long-term risk of developing rheumatoid arthritis, and up to 32 percent 10-year absolute risk of rheumatoid arthritis," the authors write.