Systematic Review Methods in Environmental Health: results of a critical interpretive synthesis to inform the evolution of systematic review guidance

Article type
Authors
Senerth E1, Tangri N1, Krammer L2, Gaby V1, Whaley P3, Johnson G4, Tsaioun K3, Morgan R5, Morgan R5
1Evidence Foundation
2George Washington University
3Evidence-Based Toxicology Collaboration
4National Council for Air and Stream Improvement
5Case Western Reserve University; McMaster University
Abstract
"Background: Systematic reviews are generally regarded as the most reliable and rigorous approach to evidence synthesis. Within the field of environmental health, systematic review methods are used to identify relationships between exposures, exposure mitigation interventions, and health outcomes. However, there are multiple strategies for conducting systematic reviews of exposures.

Objectives: This project aims to collect and describe current systematic review approaches in environmental health research and identify knowledge gaps to inform future research.

Methods: We performed an English-language search of MEDLINE via PubMed, EMBASE, and Cochrane databases from January 1, 2013 through March 30, 2023 for systematic review frameworks applied to environmental health research questions. Additionally, we searched 35 organizational websites and references of included studies to identify additional frameworks outside of the peer-reviewed literature. We purposively sampled and extracted data from frameworks that contributed new information to at least one of the following themes grounded in the PRISMA 2020 framework: research question, protocol, search strategy, study selection, data extraction, data synthesis, risk of bias assessment, overall certainty assessment, reporting findings, disclosure of funding and conflict of interest, feasibility considerations, limitations, and future research. We synthesized findings from sampled frameworks using narrative critical interpretive synthesis.

Results: From 3,417 records identified through the database search, we included 5 published frameworks. We included another 16 frameworks identified from organizational websites and citation searching; 14 frameworks were included in our purposive sample. Five frameworks addressed all of our predefined themes; all frameworks addressed at least 6 of the 9 themes. Additionally, 9 frameworks described approaches to integrating epidemiologic data with information from animal or in vitro studies. While frameworks ubiquitously included risk of bias assessment tailored to study design, frameworks differed in the degree of methodological rigor that was suggested or recommended, including inclusion of clear methods for assessing the certainty (quality) of evidence.

Conclusions: This systematic review and critical interpretive synthesis provides a comprehensive overview of systematic review approaches in environmental health. Findings may be useful to researchers who are selecting an approach for their review, or developing resources to facilitate the uptake of systematic methods for reviews of environmental exposures."