Clinical Significance Of Serum Antibody Detection In Patients With Inflammatory Bowel Disease

Objective: To detect the serum levels of p-ANCA,GAB and ASCA antibodies in patients with inflammatory bowel disease(IBD),and to explore the relationship between the three serum antibodies and disease severity,lesion locations and the clinical diagnostic significance in patients with IBD.Methods: 161 patients with IBD diagnosed in the First Affiliated Hospital of Dalian Medical University from 2016 to 2018 were selected in this study,who were further divided into UC group(105 cases)and CD group(56 cases).In UC group,there were63 males and 42 females,with an average age of 47.08±15.67 years.In CD group,there were 33 males and 23 females,with an average age of 40.07±17.46 years.According to the Montreal classification,the UC group was divided into E1group(15 cases),E2 group(46 cases)and E3 group(44 cases).According to the Mayo score,the UC group was divided into remission group(9 cases),mild group(22cases),moderate group(48 cases),and severe group(26 cases).According to the Montreal classification,the CD group was divided into L1 group(25 cases),L2 group(18 cases),L3 group(13 cases).According to the Montreal classification of disease behavior,the CD group was divided into penetrating group(9 cases),non-penetrating group(25 cases)type,and narrow group(22 cases).According to the simplified CDAI score,there were 14 cases in mild group,42 cases in moderate group.Fasting venous blood samples of 2ml were drawn in all subjects.Simple indirect immunofluorescence method was used to detect the p-ANCA,ASCA and GAB antibodies.The specificity,sensitivity,negative predictive value and positivepredictive value of serum p-ANCA,GAB and ASCA antibodies were calculated.Calculation method: specificity = true negative/(false positive + true negative);Sensitivity = true positive/(true positive + false negative);Positive predictive value =true positive/(true positive + false positive);Negative predictive value = true negative/(true negative + false negative).SPSS23.0 software package was used for statistical analysis,the mean and standard deviation of the quantitative samples were calculated,and the relationship between the three antibodies and IBD was analyzed by chi-square test or Fisher's exact probability method.P<0.05 was considered as statistically significant difference.Results:1.Comparison of positive rates of three serum antibodies between UC and CD patients:The positive rate of p-ANCA in UC group(51.43%)was higher than that in CD group(7.14%),and there was statistically significant difference between the two groups(p <0.001).The positive rate of GAB in CD group(60.71%)was higher than that in UC group(41.90%),and there was statistically significant differences between the two groups(P<0.05).The positive rate of ASCA in CD group(41.07%)was higher than that in UC group(7.62%),and there was a statistical difference between the two groups(P<0.05).2.The relationship between the three antibodies and the lesion range and severity of CD patients The positive rate of ASCA in L3 group(69.23%)was higher than that in L1group(40%)and L2 group(22.22%),and there were statistically significant differences in those groups(P<0.05).The positive rate of ASCA in the penetrating group(88.89%)was significantly higher than that in the non-penetrating group(24%)and the narrow group(40.9%),and there was a statistical difference between the three groups(P<0.05).The positive rate of ASCA in moderate activity group(50%)was higher than that in mild activity group(14.2%),and there was a statistical difference between the two groups(P<0.05).The positive rate(69.04%)in the GAB moderateactivity group was higher than that in the mild activity group(35.7%),there was a statistical difference between the two groups(P<0.05).3.The relationship between the three antibodies and the lesion range and severity of UC patients In UC group,the positive rate of p-ANCA in E2 group(62.50%)and E3 group(47.72%)was higher than that in E1 group(23.07%),there was a statistical difference between the three groups(p<0.05).The positive rate of p-ANCA in severe UC activity group(92.92%)was significantly higher than that in mild UC activity group(36.36%)and moderate UC activity group(45.83%),there was a statistical difference between the three groups(p<0.05).4.Specificity,sensitivity,positive and negative predictive values of the three serum antibodies in the CD and UC groups(1)In CD group,the sensitivity,specificity,positive and negative predictive values of serum p-ANCA antibodies were 10.00%,48.57%,10% and 48.57%,respectively.The sensitivity,specificity,positive and negative predictive values of serum ASCA antibodies were 43.33%,92.38%,76.47% and 74.05%,respectively.The sensitivity,specificity,positive and negative predictive values of ASCA/ p-ANCA combined detection were 35.00%,96.19%,84.00% and 72.14%,respectively.(2)In UC group,the sensitivity,specificity,positive and negative predictive values of serum p-ANCA antibodies were 51.43%,90%,90% and 51.43%,respectively.The sensitivity,specificity,positive and negative predictive values of serum ASCA antibodies were 7.62%,56.67%,23.53% and 25.92%,respectively.The sensitivity,specificity,positive and negative predictive values of p-ANCA/ASCA were 47.62%,98.33%,98.04% and 51.75%,respectively.Conclusion:1.p-ANCA is positively correlated with the severity of UC,which can be used as a serological indicator to reflect the severity of the disease.2.p-ANCA and GAB can be used to assist the diagnosis of UC,while ASCA can be used to assist the diagnosis of CD;p-ANCA and ASCA combined detection is helpful in differential diagnosis between CD and UC.