Validation of the Red Flags Index for Early Diagnosis of Crohn’s Disease: A Prospective Observational IG-IBD Study Among General Practitioners
Gionata Fiorino, Stefanos Bonovas, Daniela Gilardi, Antonio Di Sabatino, Mariangela Allocca, Federica Furfaro, Giulia Roda, Marco Vincenzo Lenti, Nicola Aronico, Caterina Mengoli, Enzo Angeli, Nicola Gaffuri, Laurent Peyrin‐Biroulet, Silvio Danese
Abstract
INTRODUCTION: Diagnostic delay >12 months is frequent in Crohn's disease [CD]. Recently, the International Organization for Inflammatory Bowel Disease [IO-IBD] developed a tool to identify early CD and reduce diagnostic delay. Subjects with an index ≥8 are more likely to have suspected CD (odds ratio [OR] 205, p <0.0001). We aimed to validate this questionnaire at the community level in patients seen by the general practitioners [GPs] in two large areas of Lombardy, Italy. METHODS: Consecutive adult patients referring to the GP were screened. The GPs administered the Red Flags [RF] questionnaire to the eligible patients. All patients were referred to the nearest participating centre to confirm or exclude the diagnosis of CD. Sensitivity, specificity, and positive and negative predictive values [PPV, NPV] of the RF index [RFI] were calculated. Patients lost to follow-up after the first gastroenterological visit were analysed using a non-responder imputation, assuming they were negative for CD diagnosis. RESULTS: From November 2016 to November 2019, 112 patients were included. A total of 66 subjects [59%] completed the study after the first gastroenterological visit. The prevalence of CD was 3.6% in the study population [4/112]. The RF index had 50% sensitivity, 58% specificity, 4% PPV, and 97% NPV. A combined diagnostic strategy with faecal calprotectin [FC] [RFI ≥8 and/or FC >250 ng/g] resulted in significantly improved accuracy: sensitivity 100% [29-100%], specificity 72% [55-85%], PPV = 21% [5-51%], NPV = 100% [88-100%]. CONCLUSIONS: The RF Index combined with FC is a valid tool to identify patients with high probability of having CD at early stage.