Clinical significance of serum levels of Saccharomyces cerevisiae IgA, IgG and perinuclear antineutrophil cytoplasmic antibodies in the differential diagnosis of inflammatory bowel diseases

Abstract

Background. It is important to search for biological markers with high specificity and sensitivity as a non-invasive method for accurate diagnosis of inflammatory bowel disease (IBD), in particular, differentiation of ulcerative colitis (UC) and Crohn’s disease (CD), which is important for both prognosis and treatment. The purpose of the study was to determine the titer of anti-Saccharomyces cerevisiae antibodies (ASCA) IgG, IgA, perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) and their clinical significance in patients with ulcerative colitis and Crohn’s disease. Materials and methods. The study included 49 patients with IBD who were treated at the Department of Intestinal Di­seases of the State Institution “Institute of Gastroenterology of the National Academy of Medical Sciences of Ukraine”. All patients were divided into two groups: 33 individuals with UC and 16 with CD. In addition, the patients were divided into groups depending on the severity of UC course: mild — 3, moderate — 26, and 4 individuals had severe UC. Among patients with CD, severity was moderate in 13 cases and severe CD was detected in 3 cases. p-ANCA IgG were determined by an indirect immunofluorescence assay. The serum level of ASCA IgA and IgG was evaluated by the enzyme-linked immunosorbent assay. The results were statistically processed using the Statistica 6.1 software package. Results. Most patients with UC appeared to have p-ANCA, and in patients with CD, an increased level of ASCA IgA and IgG was found. Among patients with CD, the level of ASCA IgA and IgG depended on the severity of the disease, which was confirmed by the revealed correlation between their level and the severity of the disease (r = 0.608; p = 0.012). Analysis showed that the p-ANCA IgG test for confirming the diagnosis of UC has a sensitivity of 63 % and a specificity of 86 %, whereas the presence of an elevated level of ASCA IgA or IgG for the diagnosis of CD has a sensitivity of 72 % and a specificity of 82 %. The combination of positive p-ANCA IgG and negative ASCA IgA, IgG in patients with UC showed a sensitivity and specificity of 75.6 and 68.8 %, respectively, with a diagnostic accuracy of 68.8 %. For combination of positive ASCA IgA, IgG and negative p-ANCA IgG in patients with CD, the sensitivity was 81.3 % and the specificity was 80 % with a diagnostic accuracy of 80.8 %. Therefore, the simultaneous determination of ASCA IgA, IgG and p-ANCA IgG increases the positive predictive accuracy in the differential diagnosis of UC and CD among patients with IBD. Conclusions. It was found that the separate assessment of ASCA IgA, IgG and p-ANCA IgG for the differentiation of UC and CD has lower sensitivity and specificity, but when the two tests are combined, the predictive value of a positive result and specificity can be significantly increased.