The role of serological markers in inflammatory bowel diseases

Objective: To evaluate the importance of some serological markers in differential diagnoses of inflammatory bowel diseases. Background: The differential diagnosis of inflammatory bowel diseases needs clinical, endoscopic, radiologic and laboratory results. The role of non-invasive serological markers such as ANCA, ASCA, anti-goblet antibody (GAB) and exocrine pancreatic antibody (PAB), steadily increases in the diagnosis of inflammatory bowel diseases. In this study, we evaluated the contribution as differential diagnosis and positivity rates of ANCA, ASCA, GAB and PAB levels in the patients with ulcerative colitis and Crohn's disease. Methods: 122 patients with certain-diagnosed inflammatory bowel disease, who applied consecutively to Akdeniz University Hospital- Gastroenterology Unit, are included to our study, after the University Research Ethics Committee's approval. Among these 122 patients, 70 people (57.3%) have ulcerative colitis and 52 people (42.7%) have Crohn's disease. Acquired sera after blood samples taken from patients for antibody titers centrifuged at 2500 rpm during 10 minutes, are taken to Eppendorf tubes at -20°C and were kept until the study. We examined antibody positivity by immunofluorescence method. Demographic and clinical data of patients are analyzed by SPSS 17.0 program. We used χ2 test for categorical variables and Mann-Whitney U test for continuous variables; as frequency analysis. Binary logistic regression analysis is used for detecting relative risks between variables. Results: Among included patients with Crohn's disease and ulcerative colitis, anti-TNF using is more common in Crohn's group. Severity of the attack in ulcerative colitis is more than Crohn's, the duration between the time that has been diagnosed and the first complaint time in patients with Crohn's disease is longer than patients with ulcerative colitis. Involved bowel areas in patients with Crohn's are comparatively longer than patients with ulcerative colitis. Although 18 patients (25.7%) of all (70) ulcerative colitis patients have ANCA (+) sera, just two patients of all (52) patients with Crohn's have ANCA (+) sera. 2 patients of all study population have GAB (+) sera, these two people have ulcerative colitis and also ANCA (+) sera. Four people of patients with ulcerative colitis have ASCA (+) sera. 24 people of patients with Crohn's (52) have ASCA (+) sera (46.1%). Only one person of patients with ulcerative colitis (70) has PAB (+) serum. 15 people of patients with Crohn's (52) have PAB positive sera (28.8%). In our study, we identified that exocrine pancreatic antibody (PAB) has 95.5% specificity and 93.5% positive predictive value in the differential diagnosis of Crohn's disease from ulcerative colitis; and ASCA antibody has 94.2% specificity and 85.7% positive predictive value in the differential diagnosis of Crohn's disease from ulcerative colitis. In the study group, ASCA positivity frequency is bigger than PAB positivity frequency. When compared with only using ASCA antibody; common assessment of ASCA and GAB antibodies, increased sensitivity and negative predictive values, whereas positive predictive value and specificity remained similar. Conclusions: We pointed that ANCA in the differential diagnosis of ulcerative colitis from Crohn's disease; ASCA and exocrine pancreatic antibodies in the differential diagnosis of Crohn's disease from ulcerative colitis have higher specificity and positive predictive values. However, clinical usage of antibodies is limited because their positivity rates are relatively low in the patient populations and are clinically significant whenever they were positive. Study results are compatible with other researches in the literature. Even though this study was performed on the patients with certain-diagnosed, some publications also demonstrate which these antibodies' positivity rates will can provide a classification in favor of Crohn's disease or ulcerative colitis, in the patients with unclassified inflammatory bowel disease in the scientific literature. Further studies are required about the usage of these antibodies in the patients with unclassified inflammatory bowel disease.