A Validated Score Assessing the Risk of an Intra-Abdominal Abscess in Patients with Crohn's Disease Presenting at the Emergency Department

Background and Aims: A majority of acutely ill Crohn's disease [CD] patients who present to Emergency Department [ED] will undergo an abdominal CT to rule out disease complications. We aimed to generate a simple non-invasive scoring model to predict the presence of an intra-abdominal abscess in CD patients in the ED. Methods: We performed a retrospective case-control study at four Israeli hospitals from January 1, 2010 to May 30, 2018. Inclusion criteria included patients with an established diagnosis of CD that had cross-sectional abdominal imaging performed. A total of 322 patients were included, and 81 [25%] were diagnosed with an intra-abdominal abscess. Results: In univariate analysis, ileo-colonic location (odds ratio [OR] 1.88, p = 0.0148), perianal CD [OR 7.01, p = 0.0004], fever [OR 1.88, p = 0.0247], neutrophil-to-lymphocyte ratio [OR 1.12, p < 0.0001], and C-reactive protein [OR 1.10, p < 0.0001] were significantly associated with abscess formation, whereas current use of corticosteroids was negatively associated with abscess formation [OR 0.46, 95% CI, 0.2-0.88, p = 0.0192]. We developed a diagnostic score that included five parameters that were significant on multivariate regression analysis, with assignment of weights for each variable according to the coefficient estimate. A low cut-off score of ≤7 was associated with a negative predictive value [NPV] of 93% for abscess formation, whereas a high cut-off score of >9 was associated with a positive predictive value of 65%. We validated this score with an independent cohort [area under the curve of 0.881 and NPV of 98.5%]. Conclusion: We recommend incorporating this score as an aid for stratifying acutely ill CD patients in the ED with low or high probability of the presence of an intra-abdominal abscess.