Clinical predictors of urgent findings on abdominopelvic CT in emergency department patients with Crohn's disease.

Background: Patients with Crohn's disease (CD) are frequently exposed to diagnostic radiation in emergency departments (EDs). We aimed to examine clinical predictors of urgent abdominopelvic computed tomography (APCT) findings in this population.
Methods: A retrospective cross-sectional study was performed among adults with CD presenting to 2 emergency departments with a gastrointestinal chief complaint. The outcome, APON (abscess, perforation, obstruction, new or worsening non-CD-related findings), included APCTs with new or worsening CD-related or non-CD-related urgent findings. Variables with P < 0.05 in bivariate analyses were included in a multivariable logistic regression model, which was also used to develop a risk score for APON.
Results: A total of 481 APCTs were performed and 166 (34.5%) identified APON. Variables retained in the final model were history of intestinal obstruction (odds ratio [OR]: 3.78, 95% confidence interval [CI]: 2.27-6.28), history of intraabdominal abscess (OR: 2.64, 95% CI: 1.43 to 4.88), current hematochezia (OR: 0.38, 95% CI: 0.21 to 0.68), and white blood cell count >12,000/μL (OR: 2.49, 95% CI: 1.63 to 3.84). The c-statistic was 0.72. The risk score subtracts 1 point for hematochezia, and adds 1 point for each of the other variables. Among patients with a risk score of -1, the predicted and observed risk for APON was 9% and 6%, respectively. Any score greater than -1 had a predicted and observed risk of 19.8% and higher.
Conclusions: An APON risk score of -1 is associated with a low risk of urgent APCT findings in patients with CD in the emergency department. Implementation of such a tool may support clinical decision-making in the ED setting.