Exocrine Pancreatic Insufficiency is Undiagnosed in Some Patients with Diarrhea-Predominant Irritable Bowel Syndrome Using the Rome IV Criteria

Background and aims: Irritable bowel syndrome (IBS) is one of the most frequent disorders in clinical practice, with a mean 7.6-10.8% worldwide prevalence. A study showed that 6.1% of patients with diarrhea-predominant IBS (IBS-D) had severe exocrine pancreatic insufficiency (EPI). We aimed to identify the prevalence of EPI based on fecal elastase stool testing (Fel-1) in IBS-D and the clinical characteristics that may predict the diagnosis of EPI.

Methods: Patients aged > 18 years presenting to tertiary hospital outpatient clinics with IBS-D completed validated questionnaires and gave a stool sample where Fel-1 concentration was measured. Patients with Fel-1 < 100 µg/g represented EPI and > 100 to < 200 µg/g underwent testing for pancreatic pathology with laboratory and endoscopic ultrasound (EUS) evaluation.

Results: One hundred forty patients (mean age 60 years, females 75.7%) were studied. EPI was found in 5% (95% CI 2.2-10.4), and pancreatic steatosis was the main EUS finding (71%). Dyspepsia was an independent factor associated with EPI (OR 34.7; 95% CI 4.95-366.37, p = 0.0007). After pancreatic enzyme replacement therapy (PERT), patients showed a significant improvement in the Bristol stool scale (p < 0.0001), bowel movements per day (p < 0.005), distension score (0.0009), pain score (0.0277) and IBS severity (0.0034).

Conclusion: EPI is present in 5% of patients who fulfill Rome IV criteria for D-IBS, and dyspepsia was an independent symptom strongly associated with EPI. Pancreatic steatosis was the main endoscopic ultrasound finding. After PERT therapy, patients had significantly improved stool frequency, stool consistency, abdominal pain, distension and IBS severity score.