Evaluation Of The Clinical Diagnostic Value Of Anti CarP Antibody In RA Patients

Objectives To investigate the expression of anti-carbamylated protein?CarP?antibody in serum and synovial fluid of patients with rheumatoid arthritis?RA?and its clinical value.Methods Clinical data of 247 patients with rheumatoid arthritis admitted to NingxiaMedical University General Hospital from January 2015 to June 2016 due to joint pain and 41healthy people undergoing physical examinations at the same period were collected and the results of laboratory tests and serum,Joint fluid specimens.According to the final clinical diagnosis results,they were divided into RA group?126 cases?,non-RA group?121 cases?,healthy control group?41 cases?,seronegative RA group?31 cases?and seropositive RA group?34 cases?.The joint fluid samples were divided into group RA and group OA according to the confirmed results.The concentrations of anti-CarP antibodies in serum and some patients'joint fluid were measured by ELISA method.The clinical characteristics and laboratory results of each group were compared.Using Logistic regression and ROC curve,we screened and analyzed multiple serological indicators and anti-CarP antibodies of RA diagnosis,and established the probability model of disease prediction and diagnosis.Results 1.The average concentration of anti-CarP antibody in RA group was 95.02?63.66115.83?U/ml,and the average concentration in healthy control group was 38.65?36.77,45?U/ml,the difference between two groups was statistically significant?Z=-7.252,P<0.0001?.2.The optimal cut-off value of anti-CarP antibody on ROC curve showed that the best cut-off value of RA was 63.77 U/ml.The area under the curve?AUC?was 0.78,and the 95%CI was?0.72⁰.84?,the sensitivity was 74.60%,the specificity was 71.07%,and Youden index?YI?was 0.46.Compared with the specific marker for the diagnosis of RA:AUC_{anti-CCP antibody}?0.88?>AUC_RF?0.85?>AUC_{anti-CarP antibody}?0.78?,There was no significant difference in anti-CarP antibody and RF,RF and anti-CCP antibody AUC?Z=1.29,P=0.20;Z=1.30,P=0.20?.The difference between anti-CCP antibody and anti-CarP antibody AUC was statistically significant?Z=2.28,P=0.02?.3.?1?There were significant differences in anti-CarP antibody,RF,anti-CCP antibody,AKA,ESR and CRP in univariate analysis between RA group and non-RA group?P<0.05?.?2?Binary Logistic regression analysis of the above six indicators showed that only the anti-CarP antibody,RF and anti-CCP antibodies were closely associated with the diagnosis of RA.Logistic regression analysis showed that the probabilistic prediction model of the combined diagnosis of RA was:P=1/[1+EXP?3.87+0.03*X1+2.00*X2+0.28*X3??X1:anti-CarP antibody,X2:RF,X3:anti-CCP antibodies?.The likelihood ratio test model was statistically significant?c²=163.44,P<0.001?,and the Hosmer and Lemeshow fit test showed that there was no significant difference between the experimental data and the predictive data?c²=5.30,P=0.73?.?3?The ROC curve of the combined detection and diagnosis showed that AUC_?CarP??+?CCP_??+RF?0.94?>AUC anti-CCP antibody?0.88?>AUCRF?0.85?>AUCanti-CarPantibody?0.78?.The diagnostic efficiency of combined detection was significantly different from that of anti CarP antibody,RF and anti CCP antibody single index?Z=5.59,P<0.001;Z=3.52,P=0.0004;Z=3.31,P<0.0009?.The cut-off value of RA was 0.49,the 95%CI of AUC was 0.91⁰.97,the sensitivity was 88.24%,the specificity was 88.04%and the YI was 0.76.4.The overall positive rate of anti CarP antibody in RA patients was 74.6%,and the positive rate in serological negative RA patients?RF,AKA and anti CCP antibodies were all negative?was?12/31?39%.In RF negative or anti CCP negative RA patients,the positive rates were?12/39?31%and?12/31?39%respectively,while the negative predictive values were 87.4%and 87%.There were statistically significant differences in the number of pain joints?t=3.76,P<0.001?,swelling joints?t=3.66,P<0.001?and DAS 28?t=2.73,P<0.001?between seronegative and positive RA patients.5.Anti-CarP antibodies in RA patients were not associated with clinical outcome of ESR,CRP,swollen joint count,tender joint count,DSA28?r=-0.32,P=0.724;r=-0.053,P=0.557;r=-0.126,P=0.159;r=-0.154,P=0.085;r=-0.143,P=0.111?.Serum negative RA patients DAS28 score and anti-CarP antibody concentration showed a positive correlation?r=0.94,P<0.001?.6.The average concentration of anti CarP antibody in the joint fluid of RA patients was?92.16+26.14?U/ml,the average concentration of OA patients was?56.21+24.73?U/ml,and the difference between the two groups was statistically significant?t=2.715,P=0.017?.Conclusion:1.Anti-CarP antibodies are of certain value for diagnosis of RA patients,especially in seronegative RA patients.2.The combined detection of anti-CarP antibody,RF and anti-CCP antibody can improve the diagnostic efficiency of RA.3.Anti-CarP antibody appears in the joint fluid of RA patients and is significantly higher than that of patients with OA.