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* = Presenting author

P186 Does PR3-ANCA positive ulcerative colitis represent a novel subset?

J. LI*1, S. Zhang2, H. Lv1, H. Yang1, Y. Li1, Y. Li2, J. Qian1

1Peking Union Medical College Hospital, Gastroenterology, Beijing, China, 2Peking Union Medical College Hospital, Rheumatology and Clinical Immunology, Beijing, China

Background

Anti-neutrophil cytoplasmic antibodies (ANCA) are classified into perinuclear and cytoplasmic ANCA. Atypical pANCA was closely correlated with ulcerative colitis (UC), and has been regarded as a valuable serologic marker for the differential diagnosis between UC and Crohn’s disease. PR3-ANCA, 1 kind of cANCA, has also occasionally occurred in UC patients, which favours the diagnosis of UC. UC patients with a positive PR3-ANCA had higher prevalence of extensive colitis. We previously found ANCA was not associated with colectomy and post-operative complications in Chinese UC patients. This study aimed to explore the clinical value of ANCA, especially PR3-ANCA, in Chinese UC patients.

Methods

Enrolled in this study retrospectively were 186 Chinese UC patients who were hospitalised and underwent the ANCA test from January 2005 to May 2013 in Peking Union Medical College Hospital. Univariate and multivariate analyses were used to reveal the differences amongst the data including demographic features, clinical manifestations, laboratory tests, and medications between ANCA positive and negative groups. pANCA was detected by indirect immunofluorescence (IIF), and RP3-ANCA IgG was detected by ELISA. Differences in the quantitative data between 2 groups were statistically examined through univariate analysis, using the independent t-test and Chi-square test for continuous and categorical variables, respectively. P-values were 2-tailed, and the significance level was set at p < 0.05.

Results

There were 88 (47.3%) patients with positive pANCA. The smoking status was significantly different between pANCA-positive and pANCA-negative groups with the prevalence of ex-smoker and current smoker as 21.6% vs 14.3% and 2.3% vs 11.2% (p = 0.031). There were 26 (14.0%) patients with a positive PR3-ANCA, and 25/26 (96.2%) were positive pANCA under IIF. Patients with positive PR3-ANCA had more severe disease activity, with the prevalence of severe and moderate disease as 57.7% and 42.3%, compared with 48.1% and 31.9% in patients with negative PR3-ANCA (p = 0.036) However, there was no significant difference in the age of disease onset, disease extent, extraintestinal manifestations, and the response to steroid between PR3-ANCA positive and PR3-ANCA negative groups.

Conclusion

The majority of UC patients with a positive PR3-ANCA had atypical pANCA under IIF. UC patients with a positive PR3-ANCA had more severe disease status.