Faecal calprotectin levels after rifaximin treatment in patients with irritable bowel syndrome with diarrhoea: A single-center prospective study.

Abstract Background and study aims Although unclear, the pathophysiology of irritable bowel syndrome (IBS) is considered to be multifactorial. Recent studies have suggested that IBS is a low-grade inflammatory bowel disease (IBD) with high faecal calprotectin (FC) levels. Rifaximin is a potential therapeutic agent for IBS with diarrhoea (IBS-D) due to its ability to decrease FC levels. This study evaluated the role of FC as a follow-up marker of IBS-D after short-course rifaximin treatment. Patients and methods Ninety-six patients with chronic diarrhoea who fulfilled the Rome IV criteria for IBS-D were enrolled in this study from outpatient clinics. After excluding 18 patients who did not complete the study due to treatment noncompliance or missing follow-up visits, 78 patients (mean age, 39.2 ± 6.9 years) with IBS-D and elevated baseline FC levels were included. An FC level of Results FC levels normalised in 66 (84.6%) patients, including 60 and 6 patients treated for 2 and 4 weeks, respectively. The remaining 12 (15.4%) patients with persistently elevated FC levels despite 4 weeks of treatment also showed a significant decline in their final FC levels compared with the baseline, accompanied with a significant improvement in abdominal symptoms (p = 0.001). A cutoff baseline FC value of 148.5 μg/g could predict non-responders with 100% sensitivity and 50% specificity. Conclusion Short-course oral rifaximin treatment results in FC normalisation in IBS-D patients with high baseline FC values. Therefore, FC should be considered as a biomarker of follow-up after rifaximin treatment for IBS-D.