Approaches to diagnosing irritable bowel syndrome

• Main Author: Sood, Ruchit
• Other Authors: Ford, Alexander Charles ; Law, Graham
• Published: University of Leeds 2017
• Subjects: 610
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.727215

Introduction: Differentiating irritable bowel syndrome (IBS) from organic disease is inherently challenging as symptoms can overlap. Symptom-based diagnostic criteria were developed to aid the clinician in making a positive diagnosis of IBS, and therefore avoid unnecessary invasive investigations. However, previous studies have shown these criteria perform only modestly in differentiating IBS from organic disease. Aim: The aim of this thesis is to assess the accuracy of the symptom-based diagnostic criteria, as well as address some of the limitations in their performance. Methods: A systematic review and meta-analysis was conducted in order to summarise the approaches that are currently available to aid in the diagnosis of IBS, including symptoms, biomarkers, psychological markers, and combinations thereof, as well as to understand the strengths and weaknesses of the available diagnostic tests for IBS. Using these findings, two diagnostic test studies were designed and undertaken with the intention of creating accurate, inexpensive, and easily administrable tests for clinicians consulting in routine clinical care. Results: A meta-analysis undertaken showed that symptom-based diagnostic criteria, biomarkers, and psychological markers perform only moderately well in diagnosing IBS. Combining symptoms with markers of organic disease or psychological affect seemed to represent the best way forward in improving the accuracy of diagnosing IBS. The first diagnostic test study undertaken confirmed this finding, and showed that modifications to the symptom-based diagnostic criteria with the addition of symptoms, markers of affect, and simple laboratory tests resulted in improved diagnostic accuracy. The second diagnostic test study used latent class analysis to derive and validate a model that performs with similar accuracy to the symptom-based diagnostic criteria, but importantly this method has the potential for improvement in its accuracy through the addition of clinical markers, such as faecal calprotectin. Conclusions: This thesis has shown that combining symptoms with clinical markers, markers of affect, and/or novel biomarkers leads to greater accuracy in diagnosing IBS. The novel findings of two diagnostic test studies undertaken suggests that this approach may represent the best way forward in developing an accurate and non-invasive diagnostic test for IBS.