Objective To investigate the correlation of serum human epididymal protein 4 (HE4) and phosphatidylserine-specific phospholipase A1 (PS-PLA1) expression levels with disease activity and disease outcome in patients with rheumatoid arthritis (RA).

Methods A total of 112 active RA patients were selected as the RA group, and divided into low activity group, moderate activity group and high activity group according to the disease activity score 28-joints (DAS28).In addition, 110 healthy examinees were taken as the control group.Chemiluminescence was used to detect the level of serum HE4, ELISA was applied to detect the level of serum PS-PLA1, the general information and serum index levels of the patients were collected, Pearson method was used to analyze the correlation between serum HE4, PS-PLA1 and clinical indicators in RA patients, Spearman method was used to analyze the correlation between serum HE4, PS-PLA1 and outcome, and ROC curve was used to analyze the diagnostic value of HE4 and PS-PLA1 in RA.

Results Compared with the control group, the erythrocyte sedimentation rate, serum C-reactive protein, rheumatoid factor, anti-cyclic citrullinated peptide antibody, HE4 and PS-PLA1 of patients in the RA group were obviously increased (P < 0.01).Compared with the low activity group, the levels of serum HE4 and PS-PLA1 in the moderate activity group and high activity group were increased (P < 0.05);compared with the moderate activity group, the levels of serum HE4 and PS-PLA1 in the high activity group were increased (P < 0.05).The area under the curve (AUC) of serum HE4 for diagnosing RA was 0.851 (95%CI: 0.797-0.895), with a sensitivity of 76.79% and a specificity of 82.73%;the AUC of PS-PLA1 in diagnosing RA was 0.818 (95%CI: 0.761-0.866), with a sensitivity of 77.68% and a specificity of 72.73%;the AUC of HE4 combined with PS-PLA1 diagnosis for RA was 0.903 (95%CI: 0.856-0.939), with a sensitivity of 86.61% and a specificity of 83.64%.Compared with before treatment, the levels of serum HE4 and PS-PLA1 were obviously decreased, the morning stiffness time and joint tenderness were obviously decreased, the VAS score and DAS28 score were obviously decreased after treatment (P < 0.01).Correlation analysis showed that the levels of serum HE4 and PS-PLA1 in RA patients were significantly positively correlated with erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), rheumatoid factor (RF), anti-cyclic citrullinated peptide (CCP) antibody, DAS28 score and outcome (P < 0.01).

Conclusions Serum HE4 and PS-PLA1 levels in RA patients are elevated, which are related to the degree of RA disease activity and outcome, and have certain reference values for RA diagnosis, disease evaluation, and outcome evaluation.