CORRELATION OF FECAL, PLASMA, SERUM, AND SALIVARY CALPROTECTIN TO ENDOSCOPIC AND HISTOLOGIC OUTCOMES IN PATIENTS WITH CROHN’S DISEASE

Abstract

Abstract BACKGROUND Monitoring disease activity in Crohn’s disease is important as achieving endoscopic remission significantly improves clinical outcomes. Fecal calprotectin is a common non-invasive biomarker for monitoring disease activity. However, fecal calprotectin does not always correlate with other disease activity assessments and stool samples can be difficult to collect and inconvenient to return. Thus, we aimed to compare the association between calprotectin levels in stool, saliva, and blood, and assess to their correlation with endoscopic and histologic outcomes among patients with Crohn’s disease. METHODS Nineteen patients with Crohn’s disease were included in the data analysis. Patients collected stool, blood and saliva samples within 2 days of colonoscopy. Samples were processed and stored at -80C, then assessed for calprotectin via ELISA. The Simple Endoscopic Score – Crohn’s Disease (SES-CD) was scored at the time of colonoscopy. The biopsy sample with the most severe disease activity was assessed by a single pathologist for the Robarts Histological Index (RHI). RESULTS All participants had endoscopic data and blood samples (n=19), 18 had saliva samples, and 18 had stool samples. Participants had a mean age of 32.4 (SD: 7.4). Seventy percent (n=14) were female and 45% were on biologics. The median calprotectin levels were 65.4 ug/g (IQR: 8.5, 385.0) for fecal calprotectin, 23.9 ng/ml (IQR: 15.9, 40.8) for plasma calprotectin, 977.7 ng/ml (IQR: 733.3, 1207.5) for serum calprotectin, and 3761.6 ng/ml (IQR: 874.0, 8267.2) for salivary calprotectin. Correlations (as represented by Pearson’s correlation coefficients) with endoscopic disease activity (SES-CD) were 0.83 for fecal calprotectin, 0.28 for plasma calprotectin, 0.24 for serum calprotectin, and 0.02 for salivary calprotectin. Correlations with histologic disease activity (RHI) were 0.80 for fecal calprotectin, 0.56 for plasma calprotectin, 0.16 for serum calprotectin, and -0.03 for salivary calprotectin. CONCLUSION We present preliminary findings of the relationship between calprotectin from fecal, blood, and saliva samples with endoscopic and histologic outcomes in a small sample of patients with Crohn’s disease. Larger sample sizes are needed to further examine the possible role of blood-based calprotectin assessments. In the current study, only two participants had very high SES-CD scores which influenced our ability to understand the relationship of calprotectin to endoscopic disease activity in this subset. Of interest, plasma calprotectin had a higher correlation with histology than serum, which aligns with previous studies.