P241. Faecal calprotectin reliably predicts whether surveillance can be performed in patients with long-standing ulcerative or Crohn's colitis
E. Mooiweer1, H.H. Fidder1, K.J. van Erpecum1, P.D. Siersema1, R.J. Laheij1, B. Oldenburg1, 1University Medical Centre Utrecht, Department of Gastroenterology and Hepatology, Utrecht, Netherlands
In patients with inflammatory bowel disease (IBD) active colitis impairs neoplasia detection in the setting of colonoscopic surveillance for colorectal cancer (CRC). Therefore, current guidelines recommend repeated colonoscopy after induction of remission in these cases, thereby increasing costs and burden for the patient. We investigated whether fecal calprotectin testing prior to surveillance colonoscopy might prevent ineffective surveillance in colitis patients.
Consecutive patients with Crohn's colitis (CD) or ulcerative colitis (UC) scheduled for surveillance colonoscopy collected a stool sample prior to the start of bowel cleansing. Three experienced endoscopists scored inflammation in each colonic segment. The cutoff for ineffective surveillance was defined as at least one colonic segment with moderate or severe inflammation. Calprotectin was quantitatively analyzed using the Ridascreen® (R-Biopharm, Germany) enzyme-linked immunosorbent assay. Stool samples were analyzed without reference to colonoscopy findings and vice versa. ROC statistics were used to determine cutoff values for calprotectin.
A total of 119 patients were included, of which 54 patients had CD, 59 had UC and 6 indeterminate colitis. Median (interquartile range [IQR]) calprotectin levels were 177 µg/g (IQR 39–454) for patients with CD and 115 µg/g (IQR 26–301) for UC patients. Moderate or severe inflammation was present in 14 patients (12%) (5 severe, 9 moderate: ineffective surveillance). The remaining 105 patients had mild (n = 29) or no active inflammation (n = 76) and were grouped as effective surveillance. Median calprotectin levels were significantly higher in patients in the ineffective surveillance group as compared to patients in the effective surveillance group 2318 µg/g (IQR 691–4118) vs 84 µg/g (IQR 27–276) (p < 0.01, Mann–Whitney-U test). Using ROC statistics, the predictive accuracy of calprotectin in identifying patients with ineffective surveillance was 0.92 (area under the curve). A cutoff value of 545 µg/g indicated patients with ineffective surveillance with 86% sensitivity, 89% specificity, positive predictive value of 52% and negative predictive value of 98%.
Calprotectin testing prior to a scheduled surveillance colonoscopy can be used to identify IBD patients with active endoscopic inflammation in whom surveillance will probably be ineffective. Routine use of this test might prevent useless colonoscopies and can therefore be cost effective.