The role of immunoglobulin G isotype rheumatoid factors on the diagnosis and prognosis of rheumatoid arthritis / 中华风湿病学杂志

ABSTRACT

Objective To investigate the diagnostic and prognostic value of immunoglobulin (Ig)G isotype rheumatoid factors (IgG-RF) in rheumatoid arthritis (RA).Methods Five hundred patients with RA were enrolled randomly.IgG-RF antibody was detected by enzyme-linked immunosorbent assay (ELISA).The correlations between serum IgG-RF antibody and clinical features,disease activities,laboratory of RA patients were evaluated.The comparison of continuous variables was performed by using the Student t-test or Mann-Whitney U test in accordance with normality testing.Chi-square test was performed for categorical variables.A value of P less than 0.05 was considered statistically significant.Results ① IgG-RF was positive in 41.0％ (205/500) of RA patients.In patients with anti-citrullinated protein/peptide autoanti-bodies (ACPA) negative,RF negative or the seronegative patients (both ACPA and RF were negative),the positive rate of IgG-RF was 22.4％(24/107),13.2％(17/129) and 9.1％(5/55),respectively.② Compared with patients with negative IgG-RF,patients with positive IgG-RF had higher rates of joint deformity [(58.5％(120/205) vs 39.3％(116/295),x2=17.918] and bone erosion [(75.6％(118/156) vs 60.3％(140/232),x2=9.796] (P＜0.01,respectively).③ The patients with positive IgG-RF had higher rates of elevated ESR(86.3％ vs 67.8％,x2=22.426),IgG(29.9％ vs 20.0％,x2=6.310),compared to patients with negative IgG-RF (P＜0.05,respectively),and levels of ESR [(59±35) mm/1 h vs (47±32) mm/1 h,t=3.989] and CRP [(390±450) mg/L vs (290±340) mg/L,t=3.004] was higher in IgG-RF positive group than the negative (P＜0.01,respectivelys).④ Compared with the IgG-RF negative patients,the positive group had higher smoking rates (22.9％ vs 12.5％,x2=9.227),higher current smoking rates (16.6％ vs 7.1％,x2=11.119) and higher smoking index [(107±238) vs (49±161),t=3.199](P＜0.05,respectively).Conclusion IgG-RF had its clinical values in RA diagnosis.IgG-RF is significantly associated with joint deformity,bone erosions and smoking.