Umbrella review of risk factors for inflammatory bowel disease: a study protocol

Introduction Inflammatory bowel disease (IBD) is a chronic idiopathic inflammatory disorder that arises from complex interactions between genetics, environment and gut microbiota. It encompasses Crohn's disease, ulcerative colitis and IBD-unclassified. The protracted course of IBD imposes a significant burden on patients' quality of life, economic productivity, social functioning, as well as treatment, hospitalisation and surgery. This study aims to conduct an umbrella review of meta-analyses to systematically evaluate the methodology's quality, potential biases and validity of all epidemiological evidence focused on risk factors for IBD while providing an overview of the evidence concerning IBD risk factors.Methods and analysis We will systematically search, extract and analyse data from reported systematic reviews and meta-analyses that specifically focus on the risk factors of IBD, following the guidelines outlined in Preferred Reporting Items for Overviews of Reviews. Our search will encompass PubMed, Embase, Web of Science and the Cochrane Database of Systematic Reviews from the initial period up until April 2023 (last update), targeting systematic reviews and meta-analyses based on non-interventional studies. Inclusion criteria allow for systematic reviews and meta-analyses evaluating IBD risk factors across all countries and settings, regardless of ethnicity or sex. The identified risk factors will be categorised according to the health ecological model into innate personal traits, behavioural lifestyles, interpersonal networks, socioeconomic status and macroenvironments. To assess methodological quality for each meta-analysis included in our study, two authors will employ a measurement tool to assess the methodological quality of systematic reviews (AMSTAR)-2, Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria along with evidence classification criteria.Ethics and dissemination Ethical approval is not required for this umbrella review. We will seek to submit the results for publication in a peer-reviewed journal or present it at conferences.PROSPERO registration number CRD42023417175.