CD40LG and rheumatoid arthritis: The presence of the SE was also significantly associated with increased risk for RA (HR 2.87, 95% CI 1.22 to 6.76, p=0.016); however, positivity for only one RF isotype (RF-IgA or RF-IgM) not associated with a significantly increased risk for incident IA/RA (RF-IgA positive only: HR 1.20, 95% CI 0.16 to 9.32; RF-IgM positive only: HR 1.33, 95% CI 0.47 to 3.78, p=0.5990).