OBJECTIVE: To systematically evaluate the values of 4 serum markers in the diagnosis of rheumatoid arthritis (RA). METHODS: Serum samples were obtained from 278 RA patients and 510 control subjects and the levels of rheumatoid factor (RF), anticyclic citrullinated peptide antibody (CCP), antikeratin antibody (AKA), and glucose-6-phosphate isomerase (GPI) were detected using immune turbidimetry, ELISA, indirect immunofluorescence, and ELISA, respectively. The values of these 4 serum markers and their combinations in RA diagnosis were systemically assessed. RESULTS: In RA diagnosis using one serum marker, two markers, and three or four markers, RF, RF+CCP, RF+CCP+GPI, respectively, had the highest sensitivity; CCP, CCP+AKA, and RF+CCP+AKA+GPI, respectively, had the highest specificity; CCP, CCP+GPI, and RF+CCP+AKA+GPI, respectively, had the highest positive predictive value; GPI, RF+CCP, and RF+CCP+GPI, respectively, had the highest negative predictive value; CCP, CCP+GPI, and RF+CCP+AKA+GPI, respectively, had the highest positive likely ratio; GPI, RF+CCP, and RF+CCP+GPI, respectively, had the lowest negative likely ratio. CONCLUSION: CCP, RF+CCP, and RF+CCP+GPI are the most ideal for RA diagnosis using one, two, and three or more markers, respectively. CCP is the essential marker for RA diagnosis, and a combined detection of the serum makers can significantly improve the diagnostic accuracy.
OBJECTIVE: To systematically evaluate the values of 4 serum markers in the diagnosis of rheumatoid arthritis (RA). METHODS: Serum samples were obtained from 278 RA patients and 510 control subjects and the levels of rheumatoid factor (RF), anticyclic citrullinated peptide antibody (CCP), antikeratin antibody (AKA), and glucose-6-phosphate isomerase (GPI) were detected using immune turbidimetry, ELISA, indirect immunofluorescence, and ELISA, respectively. The values of these 4 serum markers and their combinations in RA diagnosis were systemically assessed. RESULTS: In RA diagnosis using one serum marker, two markers, and three or four markers, RF, RF+CCP, RF+CCP+GPI, respectively, had the highest sensitivity; CCP, CCP+AKA, and RF+CCP+AKA+GPI, respectively, had the highest specificity; CCP, CCP+GPI, and RF+CCP+AKA+GPI, respectively, had the highest positive predictive value; GPI, RF+CCP, and RF+CCP+GPI, respectively, had the highest negative predictive value; CCP, CCP+GPI, and RF+CCP+AKA+GPI, respectively, had the highest positive likely ratio; GPI, RF+CCP, and RF+CCP+GPI, respectively, had the lowest negative likely ratio. CONCLUSION: CCP, RF+CCP, and RF+CCP+GPI are the most ideal for RA diagnosis using one, two, and three or more markers, respectively. CCP is the essential marker for RA diagnosis, and a combined detection of the serum makers can significantly improve the diagnostic accuracy.