Diagnostic performance of anti-cyclic citrullinated peptide and rheumatoid factor in patients with rheumatoid arthritis.
OBJECTIVE
To compare the diagnostic performance of rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (anti-CCP) in the diagnosis of patients with rheumatoid arthritis (RA) in Taiwan.


METHODS
Serum concentrations of RF and anti-CCP were measured in 246 cases, including 39 patients with RA and 207 patients with other rheumatic diseases (non-RA). The age, sex, clinical presentation, RF, anti-CCP results and the final diagnoses were recorded and analyzed. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+) and negative likelihood ratio (LR-) were calculated.


RESULTS
Among all 246 patients, 39 (15.9%) were diagnosed with RA and 207 (84.1%) were diagnosed with other rheumatic diseases (non-RA). In the diagnosis of RA, the sensitivity, specificity, PPV, NPV, LR+ and LR- of the RF test were 67%, 79%, 37%, 93%, 3.12, and 0.42, respectively. The corresponding data for the anti-CCP test were 79%, 98%, 86%, 96%, 32.91 and 0.21, respectively. The presence of either anti-CCP or RF increased the sensitivity to 85%, and when they both were present, the specificity increased to 98%. Among the 39 RA patients, 26 (66.7%) tested positive for RF, and 31 (79.5%) tested positive for anti-CCP. RF was positive in two of eight anti-CCP-negative patients with RA, and anti-CCP was positive in seven of 13 RF-negative patients with RA.


CONCLUSIONS
The RF and anti-CCP tests are complementary, and the co-detection of these antibodies can increase the detection rate and provide important clinical value in the diagnosis of RA. Both anti-CCP and RF positivity are useful for the diagnosis of RA, and use of both tests together improves the diagnostic sensitivity.
Department of Laboratory Medicine, Chang-Gung Memorial Hospital, Tao-Yuan, Taiwan.|Department of Medical Biotechnology and Laboratory Science, Tao-Yuan, Taiwan.|Chang Gung University, Tao-Yuan, Taiwan.
Pi-Yueh
PY
Chang
Division of Chinese Medicine, Chang-Gung Memorial Hospital and Chang Gung University, Tao-Yuan, Taiwan.
Cheng-Tao
CT
Yang
Department of Laboratory Medicine, Chang-Gung Memorial Hospital, Tao-Yuan, Taiwan.|Department of Medical Biotechnology and Laboratory Science, Tao-Yuan, Taiwan.
Ching-Hui
CH
Cheng
Chang Gung University, Tao-Yuan, Taiwan. gout@cgmh.org.tw.|Division of Rheumatology, Allergy and Immunology, Department of Internal Medicine, Chang Gung Memorial Hospital and Chang-Gung University, Tao-Yuan, Taiwan. gout@cgmh.org.tw.
Kuang-Hui
KH
Yu
D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012217:Rheumatoid Factor / Q000097:blood*; D013624:Taiwan
D001323:Autoantibodies; D015415:Biomarkers; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor
anti-cyclic citrullinated peptide; likelihood ratio; predictive value; rheumatoid arthritis; rheumatoid factor; sensitivity