The Navigation Guide - Evidence-Based Medicine Meets Environmental Health: PFOA and Fetal Growth

Abstract

Background Evaluating environmental health literature and determining the weight of evidence are critical for informing health and policy recommendations. The Navigation Guide was developed through a collaboration of 22 clinicians and scientists to improve methods of research synthesis in environmental health. This innovative systematic and transparent approach is modeled after best practices in evidence-based medicine but accounts for the differences in the evidence and decision context of environmental health. Aim To establish proof of concept of the Navigation Guide methodology to answer the question: Does developmental exposure to perfluorooctanoic acid (PFOA) affect fetal growth in humans? Methods Following a specific case study protocol, relevant studies were retrieved from several key databases and screened using exclusion criteria. Study quality was assessed using a tool based on established clinical medicine quality and risk of bias tools. Continuous effect estimates from a subset of studies (n=9) were synthesized by meta-analysis and heterogeneity among studies was assessed. The strength/certainty of the evidence was assessed using newly adapted criteria. Results We identified 18 relevant human studies. The quality rating for the body of evidence was “moderate” quality. The meta-analysis predicted that for every ng/mL increase in serum PFOA there was an 18.868 g [95% CI: -29.808, -7.928] reduction in birth weight. There were also decrements in length, ponderal index and head circumference. Key assumptions and decisions were clearly and transparently documented. Conclusions This case study demonstrates that the Navigation Guide can be used to apply the rigor of systematic review methodology to questions in environmental health. The adoption of an efficient systematic and transparent method will speed the incorporation of research into decision-making and action to prevent harm.