Development and Validation of a Novel Diagnostic Nomogram to Differentiate Between Intestinal Tuberculosis and Crohn's Disease: A 6-year Prospective Multicenter Study

Objectives Differentiating Crohn's disease (CD) from intestinal tuberculosis (ITB) remains a diagnostic challenge. Misdiagnosis carries potential grave implications. We aimed to develop and validate a novel diagnostic nomogram for differentiating them. Methods In total, 310 eligible patients were recruited from 6 tertiary inflammatory bowel disease centers. Among them, 212 consecutive patients (143 CD and 69 ITB) were used in the derivation cohort for the establishment of diagnostic equation and nomogram; 7 investigative modalities including clinical manifestations, laboratory results, endoscopic findings, computed tomography enterography features, and histology results were used to derive the diagnostic model and nomogram. Ninety-eight consecutive patients (76 CD and 22 ITB) were included for validation of the diagnostic model. Results Eight out of total 79 parameters were identified as valuable parameters used for establishing diagnostic equations. Two regression models were built based on 7 differential variables: age, transverse ulcer, rectum involvement, skipped involvement of the small bowel, target sign, comb sign, and interferon-gamma release assays (for model 1) or purified protein derivative (for model 2), respectively. Accordingly, 2 nomograms of the above 2 models were developed for clinical practical use, respectively. Further validation test verified the efficacy of the nomogram 1 with 90.9% specificity, 86.8% sensitivity, 97.1% PPV, 66.7% negative predictive value (NPV), and 87.8% accuracy for identifying CD, and the efficacy of the nomogram 2 with 100% specificity, 84.2% sensitivity, 100% positive predictive value, 64.7% NPV, and 87.8% accuracy for diagnosing CD. Conclusions The derivation and validation cohorts identified and validated 2 highly accurate and practical diagnostic nomograms for differentiating CD from ITB. These diagnostic nomograms can be conveniently used to identify some difficult CD or ITB cases, allowing for decision-making in a clinical setting.