Background: Faecal calprotectin (FC) is a marker of gut inflammation that correlates with endoscopic activity in Crohn's disease (CD). However, its accuracy to predict endoscopic postoperative recurrence remains to be completely elucidated. We aim to prospectively analyze if FC levels associate with the presence and severity of postoperative endoscopic recurrence in patients with CD. The relationships between C-reactive protein (CRP) serum levels, clinical disease activity and postoperative endoscopic recurrence are also analyzed.
Methods: A prospective multicentre observational study of diagnostic accuracy was carried out in 5 hospitals at the Ciudad Real province (Spain) from March 2014 to November 2016. Blood and faecal samples were collected from all CD patients with ileocolonic resection, at the moment of undergoing to colonoscopy to assess endoscopy recurrence. Quantitative FC was determined by enzyme-linked immunoassay tests (FC-ELISA). Clinical disease activity was assessed by the Harvey-Bradshaw index and postoperative endoscopic recurrence was graded according to Rutgeerts score.
Results: Sixty patients (35 [58.3%] male) aged 36.3 to 53.1 years were recruited. An ileal disease (L1) was present in 26 (43.3%) of cases, having the remaining an ileocolonic (L3) location. At the moment of colonoscopy, anti-TNFα and immunosuppressant therapy had been used in 54.2% and 66.1%, respectively. Table 1 summarizes main characteristics of participants.
Overall, FC concentrations, serum CRP levels and clinical disease activity were significantly higher in patients with endoscopic recurrence (Rutgeerts >i2). Area under curve (AUC) of FC in endoscopic recurrence was 0.69, slightly better than that for serum CRP (0.65). FC cut-off of 50 and 250 mcg/g obtained respectively 91.2% and 44.1% sensitivity, and 30.8% and 92.3% specificity in detecting recurrence; PPV were 63% and 88.2%, while NPV were 69.2% 55.8% for 50 and 250 mcg/g, respectively (Table 2).
The ability of FC to predict disease recurrence significantly improved in patients under biologic compared to those receiving only immunosuppressant therapy (AUC 0.76 vs. 0.59; p<0.05) AUC for serum CRP did not change according type of therapy.
Conclusions: The ability of FC to predictive endoscopic post-surgical recurrence in CD patients is moderate but improves in patients receiving treatment with anti-TNFα agents.