Development of Red Flags Index for Early Referral of Adults with Symptoms and Signs Suggestive of Crohn’s Disease: An IOIBD Initiative

Diagnostic delay is frequent in patients with Crohn's disease (CD). We developed a tool to predict early diagnosis. A systematic literature review and 12 CD specialists identified 'Red Flags', i.e. symptoms or signs suggestive of CD. A 21-item questionnaire was administered to 36 healthy subjects, 80 patients with irritable bowel syndrome (non-CD group) and 85 patients with recently diagnosed (<18 months) CD. Patients with CD were asked to recall symptoms and signs they experienced during the 12 months before diagnosis. Multiple logistic regression analyses selected and weighted independent items to construct the Red Flags index. A receiver operating characteristic curve was used to assess the threshold that discriminated CD from non-CD. Association with the Red Flags index relative to this threshold was expressed as the odds ratios (OR). Two hundred and one subjects, CD and non-CD, answered the questionnaire. The multivariate analysis identified eight items independently associated with a diagnosis of CD. A minimum Red Flags index value of 8 was highly predictive of CD diagnosis with sensitivity and specificity bootstrap estimates of 0.94 (95% confidence interval 0.88–0.99) and 0.94 (0.90–0.97), respectively. Positive and negative likelihood ratios were 15.1 (9.3–33.6) and 0.066 (0.013–0.125), respectively. The association between CD diagnosis and a Red Flags index value of ≥8 corresponds to an OR of 290 (p < 0.0001). The Red Flags index using early symptoms and signs has high predictive value for the diagnosis of CD. These results need prospective validation prior to introduction into clinical practice.