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P285 A novel scoring system for differential diagnosis between Crohn's disease and intestinal tuberculosis: A prospective study

J.H. Bae*, S.H. Park, H.-S. Lee, H.J. Lee, J.S. Soh, S. Lee, M.S. Kwak, D.-H. Yang, K.-J. Kim, J.-S. Byeon, S.-J. Myung, S.-K. Yang, J.-H. Kim, B.D. Ye

University of Ulsan Collage of Medicine, Asan Medical Center, Gastroenterology, Seoul, Korea, Republic of

Background

Although colonoscopy is useful for differentiating between Crohn's disease (CD) and intestinal tuberculosis (ITB), there have still been some limitations. Therefore, we tried to develop clinically useful predicting model in differentiating between CD and ITB using laboratory and radiologic features in addition to colonoscopic diagnosis.

Methods

We prospectively enrolled newly diagnosed CD (n = 40) and ITB (n = 40) patients from June 2011 to October 2014. On the basis of discriminant analysis using colonoscopy, laboratory and radiologic parameters, a scoring system for differentiating between two diseases was developed and was validated on additional 40 patients (CD 20, ITB 20)

Results

The colonoscopic evaluation was performed by blinded two experienced endoscopists. The accuracy of colonoscopic diagnosis was 81.2% and the positive predictive values for CD and ITB were 100% and 84.7%, respectively. On univariate analysis for laboratory and radiologic parameters, positive IgA or IgG ASCA (anti-saccharomyces cerevisiae antibody), anemia, hypoalbuminemia, elevation of ESR and abnormal lesions on small-bowel follow-through (SBFT) were significantly more common in CD, whereas QuantiFERON®-TB Gold In-Tube Test (QFT-G) and typical findings for pulmonary TB on chest X-ray (CXR) were more common in ITB. On multivariate analysis, positive IgA or IgG ASCA, positive QFT-G, abnormal SBFT and abnormal CXR were independent parameters differentiating two diseases. Final multivariate discriminant analysis was performed to construct a new predicting model: Discriminant function (DF) = 0.555 + (1.159 x CE) + (0.589 x ASCA) + (0.755 x SBFT) - (1.474 x QFT-G) - (0.633 x CXR)*. A score for CD was 1.784 and for ITB was -1.784 and the cutoff value was zero. The accuracy of discriminant function was 92.5% and the area under the curve for receiver-operating characteristic (AUROC) to assess the ability of these features to discriminate between two diseases was 0.991 (95% CI 0.978-1.000). In a validation model, the accuracy of discriminant function was 95.0% and AUROC was 0.981 (95% CI 0.950-1.000).

Conclusion

Simple laboratory and radiologic parameters including ASCA, QFT-G, SBFT and CXR are useful diagnostic aid in combination with colonoscopic evaluation for the differentiation between CD and ITB (ClinicalTtrials.gov registration number NCT01392365).

* CE: zero for indeterminate, -1 for ITB, and 1 for CD; Other parameters: 1 for positive, zero for negative