Optimising triage of urgent referrals for suspected IBD: results from the Birmingham IBD inception study.

Objective: Diagnostic delays in inflammatory bowel disease (IBD) result in adverse outcomes. We report a bespoke diagnostic pathway to assess how best to combine clinical history and faecal calprotectin (FCP) for early diagnosis and efficient resource utilisation. Methods: A rapid-access pathway was implemented for suspected IBD patients referred outside urgent 'two-week wait' criteria. Patients were triaged using symptoms and FCP. A 13-point symptom history was taken prediagnosis and clinical indices, including repeat FCP, collected prospectively. Results: Of 767 patients (January 2021-August 2023), 423 were diagnosed with IBD (208 Crohn's disease (CD), 215 ulcerative colitis (UC)). Most common symptoms in CD were abdominal pain (84%), looser stools (84%) and fatigue (79%) and in UC per-rectal bleeding (94%), urgency (82%) and looser stools (81%). Strongest IBD predictors were blood mixed with stools (CD OR 4.38; 95% CI 2.40-7.98, UC OR 33.68; 15.47-73.33) and weight loss (CD OR 3.39; 2.14-5.38, UC OR 2.33; 1.37-4.00). Repeat FCP testing showed reduction from baseline in non-IBD. Both measurements >100 µg/g (area under the curve (AUC) 0.800) and >200 µg/g (AUC 0.834) collectively predicted IBD. However, a second value ≥220 µg/g considered alone, regardless of the first result, was more accurate (Youden's index 0.735, AUC 0.923). Modelling symptoms with FCP increased AUC to 0.947. Conclusion: Serial FCP measurement prevents unnecessary colonoscopy. Two FCPs >200 µg/g could stream patients direct to colonoscopy, with two >100 µg/g prompting clinic review. A second result ≥220 µg/g was more accurate than dual-result thresholds. Coupling home FCP testing with key symptoms may form the basis of effective self-referral pathways.