Integrating chemical-specific information with general approaches to assessing exposure measurement bias in systematic reviews.

Systematic review methodology is frequently applied to environmental health evidence to support regulatory decision making. The critical appraisal of studies, a step of the systematic review process, has sometimes been challenging to apply to observational studies in which human exposures are measured using a variety of methods. We developed an instrument for gathering chemical-specific information (CSI) that serves as a supplement to existing approaches for critical appraisal of individual studies involving human exposures. We considered potential sources of exposure measurement bias for seven chemicals (hexavalent chromium, methylmercury, ethylbenzene, phthalates, bisphenol A, nitrogen dioxide, and lead) to identify CSI necessary for critical appraisal of studies of those chemicals. We then organized CSI into a format that assists the user with collecting similar information for any chemical of interest. To ensure the instrument complements a range of existing systematic review frameworks, we also examined documentation on several existing systematic review approaches with emphasis on the considerations for assessing potential exposure measurement bias. Lastly, we described three case examples that show how information like that collected using our instrument informs critical appraisals of individual studies. The CSI supplement to Critical Appraisal Tools (CSI-CAT) instrument has four main categories: 1) Overarching Considerations; 2) Exposure Setting; 3) Sampling, Laboratory, and Modeling Methods; and 4) Biological and Physiological Considerations. Use of CSI-CAT has the potential to reduce inconsistency in the way systematic review tools are applied by supplying a baseline level of chemical-specific knowledge that draws on concepts from multiple disciplines.