Background: Even though endoscopy is considered to be the gold standard for the detection of post-operative recurrence in Crohn's disease, the Crohn's disease activity index continues to be used for this purpose.
Aim: The aim of this study was, therefore, to assess the accuracy of Crohn's disease activity index to detect post-operative recurrence in Crohn's disease in comparison to endoscopy.
Patients and methods: The study was performed in 110 patients submitted to intestinal resection for Crohn's disease of the terminal ileum. Crohn's disease activity index score was assessed at 6, 12, 24 and 36 months after surgery. At the same intervals colon-ileoscopy was performed in all patients. The Receiver Operating Characteristic analysis was used to assess the accuracy of the Crohn's disease activity index score. Some routine laboratory variables were also analyzed.
Results: Crohn's disease activity index was able to discriminate patients with and without recurrence in 65% of the cases. Considering 150 the standard cut-off value of Crohn's disease activity index, this figure corresponds to a specificity of 89% and a sensitivity of 30%. Out of the laboratory variables erythrocyte sedimentation rate, chloraemia and serum albumin, globally considered in a discriminant function, showed a predictive ability significantly better than Crohn's disease activity index (z = 1.97; two tailed p-value = 0.04). These variables were able to discriminate patients with and without recurrence in 88% of the cases, and at the same value of specificity for the Crohn's disease activity index reached double value of sensitivity (65%). Positive and negative predictive values of laboratory variables (80% and 78%, respectively) were better than the corresponding values of the Crohn's disease activity index score (71% and 56%, respectively).
Conclusions: These results indicate that the Crohn's disease activity index alone is inadequate for detection of post-operative recurrence in Crohn's disease.