The Pro Argument

Irritable bowel syndrome (IBS) patients are at risk of being subjected to numerous investigations only to be told “I can find nothing wrong with you.” This produces an undesirable uncertainty, anxiety, and demand for further tests which can be prevented by a positive symptom-based diagnosis. Several criteria including the Manning, Kruis, and Rome I criteria have been validated and give useful positive likelihood ratios of 2.9–5.9. However, sensitivity remains low at 0.65–0.84, meaning that some patients who clinicians feel should be labeled IBS are not. Nonetheless, given the high prevalence of IBS, the positive predictive value of clinical criteria is high and the diagnosis can be made with some authority if patients meet the criteria in the absence of alarm features. There is a consensus that making a firm symptom-based diagnosis reduces patient anxiety and allows better management. Future developments of the criteria which could involve adding the results of laboratory tests might improve their clinical performance. Furthermore adding biomarkers of underlying mechanisms could improve their usefulness as a guide to treatment. Their use in clinical trials has undoubtedly proved valuable in improving the consistency of the results but all recent IBS trials have shown large numbers needed to treat (NNT) suggesting that further refinement is needed if we are to achieve our aim of targeting our treatments to the patients who will specifically benefit.