Rapid fecal calprotectin test for prediction of mucosal inflammation in ulcerative colitis and Crohn disease: a prospective cohort study

INTRODUCTION Fecal calprotectin (FC) is a well‑established biomarker of intestinal inflammation in Crohn disease (CD) and ulcerative colitis (UC). However, standard laboratory methods are time‑consuming and not always useful in clinical practice.
OBJECTIVES We analyzed the efficacy of a rapid bedside FC test to detect disease flares in a hospital setting. We also assessed the influence of disease location on the diagnostic accuracy of FC. 
PATIENTS AND METHODS This prospective study included 140 patients (46 with UC; 94 with CD). FC was measured by an enzyme‑linked immunosorbent assay (ELISA) and by the rapid Quantum Blue® test. Endoscopic activity was assessed using the Mayo endoscopic subscore or the Simple Endoscopic Score for Crohn’s Disease (SES‑CD). 
RESULTS FC levels highly correlated with endoscopic activity in CD (area under the receiver operating characteristic curve [AUC], 0.83) and UC (AUC, 0.80), with the cut‑off values of 238.5 μg/g and 499 μg/g, respectively. FC levels increased dynamically even with early signs of inflammation both in CD (SES‑CD, 4–10 vs 0 points: 252 vs 100.0 μg/g; P = 0.02) and UC (Mayo subscore, 1 vs 0 points: 323.3 vs 100.0 μg/g; P <0.001). In UC, FC levels were lower in proctitis than in left‑sided UC and pancolitis (340.0, 500.0, and 421.5 μg/g, respectively), but the differences were not significant. In CD, lower FC values were observed in isolated small bowel disease.
CONCLUSIONS FC levels increased dynamically even with mild signs of intestinal inflammation. The rapid Quantum Blue® test presents a potential alternative to the time‑consuming ELISA, because its diagnostic accuracy is not influenced by disease location. It may be useful in the hospital setting, providing faster diagnosis and allowing cost reduction by lowering the number of endoscopic procedures.