Serum biomarkers for irritable bowel syndrome

BACKGROUND AND AIM Irritable bowel syndrome (IBS) is one of the most frequent and common functional gastrointestinal diseases. For its diagnosis, clinical criteria are still used. Our objective was to asses if there are specific serum biomarkers for the diagnosis of IBS, and as secondary purpose we aimed to analyze the specificity and sensitivity - where determined - for the proposed biomarkers. METHODS We performed a review in order to find potential serum biomarkers useful for the diagnosis of IBS. MEDLINE and Cochrane databases were searched in May 2015. Inclusion criteria were: original studies that assessed serological markers in IBS patients, markers potentially useful for diagnosing IBS or in differentiating subtypes of IBS. Exclusion criteria were biomarkers assessed in IBS patients not for the diagnosis of IBS, but used in order to exclude other conditions or diseases in these patients; or markers that were not addressed to IBS; or papers that assessed only fecal biomarkers, or histological or surrogate - indirect biomarkers. RESULTS From the 268 papers retrieved by our initial search, using a modified strategy we identified 58 papers. Out of the 58 papers retrieved by the search, six papers were selected and other nine studies were eventually analyzed. Of the results of the computerized search, a number of papers were not included for various reasons: some were not related to the subject (26), others were not appropriate for the subject (19) because they addressed inflammatory bowel disorders, in others fecal markers were the subject of the study, six were reviews, others were impossible to gain access to (1). Twelve out of the 14 studies included are case-control studies, IBS diagnosis being established in all of the selected results based on the Rome criteria. A higher sensitivity of 81% was found using a combination of markers but with lower specificity, while one study that assessed also a combination of markers, found a higher specificity but sensitivity was only 50 %; none reached the characteristics for an ideal biomarker. CONCLUSIONS For the moment, just one serum biomarker with a high specificity and sensitivity useful in the diagnosis of IBS was identified. We consider that in the future a combination of several biomarkers could better identify IBS than a single biomarker. Therefore, clinical criteria are still to be used for the diagnosis of IBS in attendance for newer research or validation of results.