For children with Crohn’s disease, fecal calprotectin levels below 300 mcg indicated mucosal healing, while values below 100 mcg signified deep healing in a multicenter, 151-patient study.
Sensitivity was 80% for mucosal healing and 71% for deep healing, while specificities were 81% and 92%, respectively, said Inbar Nakar of the Hebrew University of Jerusalem, with her associates. In line with prior studies, adding C-reactive protein (CRP) to fecal calprotectin improved neither sensitivity or specificity, the researchers wrote in Clinical Gastroenterology and Hepatology.
Bowel healing is a crucial goal in Crohn’s disease (CD). Because pediatric transmural healing had not been studied, the researchers analyzed data from the ImageKids study, a multicenter effort to develop magnetic resonance enterography (MRE) measures for CD patients aged 6-18 years. Participants averaged 14 years old with a standard deviation of 2 years. Assessments included MRE, complete ileocolonoscopic evaluation, CRP, and fecal calprotectin. The researchers defined mucosal healing as a Simple Endoscopic Severity Index in Crohn’s Disease score below 3, transmural healing as an MRE visual analog score below 20 mm, and deep healing as transmural plus mucosal healing.
Nearly one-third of patients had healing only in the mucosa or the bowel wall, but not both; 6% had mucosal healing but transmural inflammation, and 25% of children had transmural healing but mucosal inflammation. In addition, 14% of children had deep healing, and 55% of children had both mucosal and transmural inflammation. Those findings highlight “the discrepancy between mucosal and transmural inflammation and the importance of evaluating the disease by both ileocolonoscopy and imaging,” the researchers wrote.
Median calprotectin levels varied significantly by healing status (P less than .001). They were lowest (10 mcg/g) for deep healing, followed by either transmural or mucosal inflammation, and were highest (median, 810 mcg/g) when children had both mucosal and transmural inflammation. Calprotectin in children with deep healing had an area under the receiver operating characteristic curve value of 0.93 (95% confidence interval, 0.89- 0.98). In contrast, CRP level identified children with deep healing with an AUROC value of only 0.81 (95% CI, 0.71-0.90).
Although “calprotectin level is driven primarily by mucosal healing, [it] is still superior to CRP,” the investigators concluded. “Although a calprotectin cutoff [less than] 300 mcg/g predicted mucosal healing, a lower cutoff of [less than] 100 mcg/g may be more suitable to predict deep healing.” However, they emphasized that fecal calprotectin level is only moderately accurate in predicting mucosal or transmural healing in children with CD. They advised physicians to “be familiar with the predictive values of each cutoff before incorporating them in clinical decision making.”
An educational grant from AbbVie funded the ImageKids study. AbbVie was not otherwise involved in the study. Two coinvestigators disclosed ties to AbbVie and other pharmaceutical companies. There were no other disclosures.
SOURCE: Nakar I et al. Clin Gastroenterol Hepatol. 2018 Mar 2. doi: 10.1016/j.cgh.2018.01.024.
