Clinical and laboratory features of rheumatoid arthritis that has negative serum autoantibodies

Objective To investigate the clinical and laboratory features of auto antibody-negative rheumatoid arthritis(RA).Method The clinical features and laboratory parameters were compared between auto-antibndy-negative(n=30)and-positive(n=217)RA patients.The patients with osteoarthritis(OA,n=34) were used as controls.Results Thirty(12.1%)of 247 RA patients were auto-antibody-negative.It was shown that morning stiffness of the joints in auto-antibody-negative RA was shorter than that of auto-antibody-posi- tive RA patients(P0.05).The levels of IgG,IgA and gamma hemoglobin in auto-antibody-negative RA pa- tients were significantly lower than those in patients with positive antibodies(P0.01).However,as compared with OA patients,auto-antibody-negative RA individuals had higher levels of ESR,CRP,IgM and gamma hemoglobin(P0.05).Conclusions More than 10% RA patients are auto-antibody-negative.ESR,CRP,IgM and gamma hemoglobin are valuable parameters in the diagnosis of auto-antibody-negative RA patients.