Neighbourhood environment as a risk factor for adverse health outcomes through association with the microbiome: protocol for a scoping review

INTRODUCTION: The connection of the microbiome to human health intersects with the physical environment of humans. Each microbiome location can be influenced by environmental conditions that relate to specific geographical locations, which in turn are influenced by social determinants of health such as a neighbourhood. The objective of this scoping review is to explore the current evidence on the relationships between microbiome and neighbourhood to explain microbiome-related health outcomes. METHODS AND ANALYSIS: Arksey and O’Malley’s literature review framework will be employed throughout the process, as well as Page, et al’s 2020 Preferred Reporting Items for Systematic Review and Meta-Analysis updated workflow to process search results. The literature search will be completed using PubMed/Medline (NLM), Embase (Elsevier), Web of Science, Core Collection (Clarivate Analytics), Scopus (Elsevier), medRxiv preprint server and Open Science Framework server. The search will be conducted using a list of pre-identified Medical Subject Headings (MeSH) terms relating to neighbourhood, microbiome and individual characteristics. There will be no date or language restrictions used in the search. In order to be included in the study, a piece must include an evaluation of the relationship between microbiome diversity and neighbourhood (including at least one measurement of the neighbourhood and at least one human microbiome site). Excluded from the review will be those works that do not include all of these measures, literature reviews based on secondary sources and postmortem populations with no report of premortem health factors. The review itself will be an iterative process completed by two reviewers, with a third individual identified to break ties. Documents will be undergoing a risk assessment of bias in order for the authors to comment on the quality of the literature in this area. Finally, results will be discussed with identified stakeholders, including individuals connected to neighbourhoods facing structural inequity and experts in the topics of study through a community advisory board, for their feedback and knowledge transfer. ETHICS AND DISSEMINATION: This review does not require ethical approval. Results of this search will be disseminated through peer-reviewed publications. Furthermore, this work is completed in conjunction with a community advisory board so as to ensure dissemination to multiple stakeholders.