BackgroundThe determination of rheumatoid arthritis (RA) activity remains an important clinical task nowadays and it is a long and difficult process. There is no single approach to assess the activity of RA. The gold standard for evaluating RA activity is composite indexes, for example, DAS28. However, composite indices are not reliable in evaluation of the disease activity in patients with RA, as having a subjectity assessment. New biomarkers that reflect the immune inflammatory process in joints in RA is of great scientific importance. 14-3-3η and calprotectin markers in plasma are considered as promissing.ObjectivesTo assess the value of 14-3-3η and calprotectin in plasma as additional markers in RA activity determination.Methods48 patients were examined with reliable diagnosis of RA, according to the ACR 2010 criteria. The mean age was 59 years, mean duration of the disease was 12.8 years. 4 patients in the group were in remission, 2 had low degree of RA activity, 20 - moderate, 22 – high. RA activity was determined according to the DAS28 ESR index. The concentrations of 14-3-3η and calprotectin in the blood plasma were determined by ELISA (LLC «SPF «Abris+»). The obtained results were compared with laboratory (ESR, CRP) and clinical (tender joint count (TJC), swollen joint count (SJC), VAS, DAS28) parameters of RA activity.Results14-3-3η and calprotectin proteins in plasma and ESR highly correlated with DAS28 (r = 0.84; r = 0.65; r = 0.53), while CRP had moderate correlation with RA activity (r = 0.34). 14-3-3η and calprotectin proteins had high correlation with TJC (r = 0.68; r = 0.61) and moderate correlation with SJC (r = 0.56; r = 0.41); ESR and CRP had weaker correlation (r = 0.15; r = 0.13; r = 0.02; r = 0.08) respectively.The ROC analysis showed that sensitivity, specificity, and diagnostic accuracy of high RA activity determination are significantly higher for 14-3-3η (AUC = 0.98, p <0.001) and calprotectin (AUC = 0.89, p <0.001) than for ESR (AUC = 0.81, p <0.001) and CRP (AUC = 0.72, p <0.001). The proteins 14-3-3η and calprotectin reflect the relationship with the SJC (AUC = 0.89, p <0.0001; AUC = 0.79, p = 0.002) with higher diagnostic accuracy, sensitivity and specificity, comparing with ESR (AUC = 0.63, p = 0.19) and CRP (AUC = 0.51, p = 0.88).It was also found, that calprotectin (AUC = 0.8, p <0.001) and 14-3-3η (AUC = 0.79, p <0.001) had greater sensitivity and specificity, as well as diagnostic accuracy, in TJC determination, compared with ESR (AUC = 0.57, p = 0.4) and CRP (AUC = 0.52, p = 0.8). Determining the relationship between biomarkers and the patient‘s subjective assessment of RA activity (VAS), significant difference between 14-3-3η (AUC = 0.68, p = 0.06), calprotectin (AUC = 0.63, p = 0, 16), ESR (AUC = 0.64, p = 0.14) and CRP (AUC = 056, p = 0.57) was not detected.Conclusion14-3-3η and calprotectin proteins in plasma are new promising biomarkers of immunoinflammatory process in joints in RA assessment, because they are more sensitive and specific markers of the disease activity, th...