Anti-perinuclear Factor as Diagnostic Marker in Rheumatoid Arthritis

A study of the roles of some immunological biomarkers in the diagnosis of rheumatoid arthritis

Autoimmune rheumatoid arthritis (RA) is a systemic condition closely correlated with a variety of autoantibodies (Abs) that could be considered diagnostic and prognostic markers. The current research was designed to detect the diagnostic values for a number (n) of these auto-Abs in RA detection and to evaluate the accuracy of a combined diagnostic scheme. This prospective study was conducted between September 2021 and August 2022 and included 110 subjects with RA, 70 individuals with other autoimmune disorders as positive controls (PC), and 50 unrelated, apparently healthy individuals as healthy controls (HC). The eligibility criteria for all study groups were followed stringently. An enzyme-linked immunosorbent assay (ELISA) was employed to measure rheumatoid factors (RF), cyclic citrullinated peptide antibodies (CCP-Abs), mutated citrullinated vimentin antibodies (MCV-Abs), anti-perinuclear factor antibodies (APF-Abs), and anti-keratin antibodies (AKA). We calculated the specificity, sensitivity, and predictive values of all auto-Abs. Significantly higher levels of anti-CCP-Abs, anti-MCV-Abs, APF-Abs, and AKAs were reported in the RA patients compared to the HC and PC subjects. RF levels, however, were only statistically elevated when compared to the HC individuals. Anti-APF-Abs had a higher sensitivity rate (70.9%), and anti-CCP-Abs had a higher specificity rate (94.16%) compared to other auto-Abs, whereas the combined detection scheme revealed a higher sensitivity (81.81%) and excellent specificity (90.83%) compared to the two former auto-Abs. Anti-perinuclear factor-Ab was a highly sensitive test, and CCP-Ab was a surpassingly specific assay for identifying RA. Furthermore, the combined detection scheme is an essential serological approach for RA diagnosis and crucial in differentiating this disease from other autoimmune diseases, thus promoting early diagnosis and treatment.

Comparison of the analytical and clinical performances of four anti-cyclic citrullinated peptide antibody assays for diagnosing rheumatoid arthritis

INTRODUCTION/OBJECTIVES

Anti-cyclic citrullinated peptide antibody (anti-CCP) is one of the most important serologic markers for diagnosing rheumatoid arthritis (RA). This study aimed to compare the analytical and clinical performances of the second- and third-generation anti-CCP assays.

METHODS

Four automated anti-CCP assays were evaluated: Chorus anti-CCP (Diesse Diagnostica), Elecsys anti-CCP (Roche Diagnostics), Atellica® IM anti-CCP IgG (Siemens Healthineers), and Quanta Flash® CCP3 (Inova Diagnostics Inc.). Analytical performance included the precision, linearity, correlation, and concordance rate. For evaluating the clinical performance, 240 patient samples (120 positive and 120 negative samples, determined by the Chorus anti-CCP assay) were used, including those with a diagnosis of RA (n = 132) and non-RA (n = 108). Using receiver operating characteristic (ROC) curve analysis, the sensitivity and specificity were evaluated.

RESULTS

All four assays that were evaluated showed good precision and linearity, and their correlation and concordance rates were in acceptable ranges. The area under the curve (AUC) values ranged from 0.888 to 0.914, showing a good diagnostic performance. The sensitivity and specificity of all assays were similar (88.0-97.2%).

CONCLUSIONS

All four anti-CCP assays showed good analytical and diagnostic performances for diagnosing RA. After adjusting the cutoff values, these assays are expected to show enhanced sensitivity and specificity. Key Points • Previous studies have described the diagnostic performance of a few immunologic markers in RA diagnosis, but nothing has been proven to be sufficiently good in clinical practice. • All four automated anti-CCP assays showed good analytical and diagnostic performances for diagnosing RA in clinical practice. • After adjusting the cutoff values, these assays are expected to show enhanced sensitivity and specificity. • The present study provides reassuring evidence that any of the studied commercially available anti-CCP tests for detecting rheumatoid arthritis provide similar diagnostic information to institutions that adopt these specific testing systems.

Diagnostic value of autoantibodies combined detection for rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, inflammatory and autoimmune disease, there are many autoantibodies produced during disease progression in the patients' serum, and this work is to select a best detection scheme for RA diagnosis.

METHODS

Autoantibody levels including rheumatoid factor (RF), anti-cyclic citrullinated peptide (CCP), mutated citrullinated vimentin (MCV), anti-keratin antibodies(AKA), anti-perinuclear factor (APF), and Ig heavy chain binding protein (BIP), were measured, and the sensitivity, specificity, predictive values, accuracy, and Youden's index of different combining forms were all calculated in RA patients, disease, and healthy control group. The differences in the positive rates of the three groups were compared between any two of them.

RESULTS

Generally speaking, the sensitivity of the autoantibodies detected in parallel combination was higher than that in tandem, which was more specific. The sensitivity of anti-MCV and RF calculated in parallel (87.61%) was obviously better than that of anyone autoantibody (P<.05), and only increased slightly even if more autoantibodies were tested in parallel (P>.05). The specificity of anti-CCP and BIP measured in tandem (95.92%) was obviously higher than that of anyone autoantibody (P<.05). While increasing the detected number of autoantibody from two kinds to three or more, the specificity was improved insignificantly (P>.05).

CONCLUSION

Anti-BIP and CCP antibodies detected in tandem combination can obtain higher specificity, and have good clinical value for the differential diagnosis of RA.