Does Breath Testing (BT) or Clinical Signs and Symptoms Help to Distinguish Irritable Bowel Syndrome (IBS) Patients from Small Intestinal Bacterial Overgrowth (SIBO) Patients?

Abstract

Purpose: There is considerable overlap in symptoms between individuals with IBS and SIBO. The diagnosis of IBS is made based upon clinical findings and appropriate exclusion criteria for other disorders. SIBO is often suspected on clinical grounds and confirmed with breath testing or a clinical response to therapy. BT for SIBO is indicated by Medicare only if diarrhea is present. Can the distinction be made on clinical grounds or should additional BT be performed? Methods: A prospectively collected database of patients undergoing breath testing for SIBO has been maintained at our institution since March 2012. Data was evaluated from inception to April 2013. Signs, symptoms, lactulose breath hydrogen(HBT) and methane breath testing (MBT) using a Quintron Breath Tracker 10344 gas chromatograph was evaluated. Logistic regression adjusted for age and gender of the clinical profile characterized by diarrhea, constipation, bloating, nausea, vomiting or pain was applied to distinguish IBS patients from SIBO. Results: A total of 305 patients were evaluated for SIBO who presented with the symptoms of diarrhea, constipation, bloating, nausea, vomiting or pain alone or in various combinations. 236/305 (77%) met clinical Rome III criteria for IBS. 163/236 (69%) IBS-diarrhea predominant, 32/236 (14%) IBS constipation predominant and 41/236 (17%) IBS-mixed. 136/305 (44.6%) were positive for SIBO undergoing lactulose breath testing. 117/135 (87%) positive HBT and 25/135 (19%) positive MBT. There was a significant increase in constipation in patients diagnosed with SIBO for all patients (odds ratio [OR] 1.7; 95%CI 1.02-2.83; P=0.04) and IBS patients (OR 1.78; 95% CI 1.03-3.09; P=0.04). We observed a nonsignifi cant decrease in diarrhea in patients diagnosed with SIBO for all patients (OR 0.91, 95% CI 0.57-1.45; P=0.69) and IBS patients (OR 0.72; 95% CI 0.41-1.27; P=0.26). We also observed a non-significant association of SIBO diagnosis with nausea, vomiting, bloating, diarrhea, and pain. Conclusion: 1. Among all patients and IBS patients only the clinical symptom of constipation was supportive of SIBO. 2. Using diarrhea as the indication for BT is not supported by our data. 3. BT are important in identifying SIBO patients who meet criteria for IBS.