Alternatively spliced EDA‐containing fibronectin in synovial fluid as a predictor of rheumatoid joint destruction

Objectives.Fibronectin containing the EDA region (EDA + Fn), a molecule important for rheumatoid joint destruction, was measured in relation to the progression of joint destruction in rheumatoid arthritis (RA).Methods.Total Fn and EDA + Fn were measured by ELISA, and the concentrations of Fn in plasma and synovial ¯uid were compared prospectively for 2 yr with the progression of joint destruction in 41 knee joints of 37 patients with RA.The extent of joint destruction was assessed by the Larsen score and joint space narrowing in X-ray ®lms taken before and 2 yr after measurement of EDA + Fn.Results.The concentration of synovial ¯uid EDA + Fn showed a positive correlation with the progression of joint destruction in RA (r = 0.78).While total Fn in synovial ¯uid also showed a correlation with joint destruction (r = 0.54), total Fn and EDA + Fn in plasma showed no correlation with joint destruction.The concentration of synovial ¯uid EDA + Fn was signi®cantly higher in patients who underwent joint replacement after the measurement of EDA + Fn than in those who did not receive surgery (P < 0.029).Conclusion.Synovial ¯uid EDA + Fn can be a predictor of subsequent joint destruction in RA.