P166 Predictive markers of Crohn’s disease in small bowel capsule endoscopy
Mattila, J.(1);Stenholm, T.(1);Löyttyniemi, E.(2);Koffert, J.(1);
(1)Turku University Hospital, Department of gastroenterology, Turku, Finland;(2)University of Turku, Department of Biostatistics, Turku, Finland;
To distinguish between functional gastrointestinal disorders like irritable bowel syndrome (IBS) and Crohn’s disease (CD) can be a burden. The diagnosis is based on symptoms and findings in laboratory tests, endoscopy and imaging. As CD can be limited to small bowel, the diagnosis often requires small bowel capsule endoscopy (SBCE), which is time consuming for both the patient and clinician.
To answer this problem, we conducted a retrospective study of 374 patients who underwent SBCE for suspected small bowel CD in Turku University Hospital between 2012 and 2020 and gathered data on the patient’s laboratory, imaging and endoscopic findings at the time of SBCE. The patient’s history, medications and procedures related to CD were also documented after SBCE. SBCE findings were graded along CECDAI (Capsule Endoscopy Crohn’s Disease Activity Index) -scoring system. The main goal was to find predictive markers to rule out clinically significant small bowel CD without proceeding to SBCE.
Small bowel CD was diagnosed in 110 (29.4%) patients (CD-group). The mean follow-up time for the whole population was 4.4 years. Fecal calprotectin (FC), serum albumin (Alb) and erythrocyte sedimentation rate (ESR) were significantly different between CD and non-CD-groups (p=<0.001, 0.025 and 0.022). Hemoglobin (Hb) and C-reactive protein (CRP) had no significant differences between the two groups (p=0.59, 0.24). FC <50ug/g had sensitivity 96.4%, specificity 19.6%, positive predictive value (PPV) 34.6% and negative predictive value (NPV) 92.5% for small bowel CD. 13 (11.8%) patients in CD-group had FC <100ug/g. CECDAI-score has no previously established clear cut-off-value for the diagnosis of CD. In this study 98.2% of patients in CD-group had CECDAI of 3 or more whereas 90.5% of patients in non-CD-group had CECDAI less than 3 (PPV=81.1%, NPV=99.1%). Sensitivity and specificity were the highest between CECDAI 2.5 and 3.5. Small bowel imaging also had relatively low sensitivity (65.1%) and specificity (72.7%) considering small bowel CD (PPV=52.2%, NPV=81.8%).
These findings underline our experience, that diagnosis of small bowel CD can be difficult. In this study, we found out that clinically relevant small bowel CD is possible even with FC<100ug/g. Based on our results, we suggest for a follow-up with FC before SBCE for patients with no endoscopic ileitis, negative imaging results and FC <50 ug/g. CECDAI-score of 3 would be a reasonable cut-off value for small bowel CD.