Noninvasive biomarkers as surrogate predictors of clinical and endoscopic remission after infliximab induction in patients with refractory ulcerative colitis

Background/Aims: Treatment of refractory ulcerative colitis (UC) is a clinical challenge, and after biological therapy, monitoring clinical and endoscopic responses is fundamental. We aimed to investigate and compare the predictive power of different noninvasive parameters for clinical remission and mucosal healing after infliximab induction therapy in refractory UC patients. Patients and Methods: Serum and fecal biomarkers, including hemoglobin, white blood cells, erythrocyte sedimentation rate, C-reactive protein (CRP), and fecal calprotectin (FC), and colonoscopy were assessed in 44 patients with refractory UC before and after (week 12) infliximab induction. Clinical and endoscopic responses were measured by clinical Mayo score and endoscopic Mayo subscore, respectively. Results: After infliximab induction, 54.5% and 65.9% had clinical remission and mucosal healing, respectively. Post-induction CRP and FC were significantly lower in clinical responders versus nonresponders (P = 0.01 and 0.001, respectively) and in patients with mucosal healing than without (P < 0.001). Among all the parameters tested, FC had the best predictive value of clinical remission [Area under the curve (AUC = 0.826)] and mucosal healing (AUC = 0.949). Post-induction FC had 87.5% sensitivity and 89% specificity (cut-off < 100 mu g/g) for predicting clinical remission and 89.7% sensitivity and 93.3% specificity (cut-off < 58 mu g/g) for predicting mucosal healing. Conclusions: Post-infliximab induction FC can be used as a surrogate marker for predicting clinical remission and mucosal healing in refractory UC patients.