Objective To investigate the expression level and clinical significance of serum angiotensinogen (AGT) and amyloid 4 (SAA4) in patients with rheumatoid arthritis (RA).

Methods A total of 43 RA patients in active period (active group) and 37 RA patients in remission period (remission group) were selected as research objects, and 40 patients with joint pain and swelling (non-RA group) and 43 healthy volunteers (control group) were selected as controls. Levels of serum AGT, SAA4 and inflammatory factors such as C reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected in all the groups. Pearson correlation test was used to analyze the correlations of serum AGT and SAA4 with inflammatory factors in RA patients; the multivariate Logistic regression model was used to analyze the relationships of serum AGT and SAA4 with the occurrence of RA; the receiver operating characteristic (ROC) curve was used to analyze the values of serum AGT and SAA4 levels in diagnosing RA.

Results Levels of serum AGT, SAA4, CRP, TNF-α and IL-6 and the Disease Activity Score-28 items (DAS28) score in the active and the remission groups were significantly higher than those in the non-RA and the control groups, and levels of serum AGT, SAA4, CRP, TNF-α and IL-6 and DAS28 in the active group were also significantly higher than those in the remission group (P < 0.05). Pearson correlation test showed that serum AGT and SAA4 were positively correlated with DAS28, CRP, TNF-α and IL-6 in RA patients (P < 0.05). Multivariate Logistic regression analysis showed that increased AGT and SAA4 were the independent risk factors for the occurrence of RA OR(95%CI) were 1.247(1.108 to 1.405) and 1.131(1.042 to 1.227) respectively. ROC curve analysis showed that the areas under the curve and its 95%CI AUC(95%CI) of serum AGT and SAA4 alone and their combination for the diagnosis of RA were 0.724(0.501 to 0.953), 0.778(0.600 to 0.932) and 0.862(0.773 to 0.925) respectively.

Conclusion The elevated levels of serum AGT and SAA4 in RA patients are closely related to disease activity and inflammatory factors, and combined detection of serum AGT and SAA4 levels has high diagnostic value for RA.