Table 2.

Example considerations relating to sensitivity of study methods (ability to detect an effect) – animal toxicology studies

Element	Example Questions	Example Applications in Risk of Bias Tools
Animal model Species, strain, sex	• Is the selected animal model likely to underrepresent changes in the endpoint(s) under study? [Consider the extent to which the species, strain, or sex is sensitive or suitable for the specific effects or endpoints under evaluation; note: consider current knowledge regarding the relative susceptibility or resistance of the selected model; sensitivity is generally assumed when specific knowledge otherwise is lacking]	• NTP OHAT: not explicitly considered; relevance of animal species considered under applicability • SciRAP: considered under relevance criteria • SYRCLE: not explicitly considered (could be included in “other sources of bias”)
Design Evaluation of relevant endpoints	• Are sensitive methods used for endpoint evaluation? [or, what is the reliability, specificity, and validity of the method used for endpoint evaluation?] Is the timing of endpoint evaluation appropriate for detecting an effect (e.g., is the latency period sufficient to allow development of the endpoint; does the animal age at evaluation allow for accurate measurement of the endpoint; for some endpoints, evaluation too early or too late may mask an effect) • Use of positive and negative assay controls, where applicable (e.g., positive controls may not be needed for established protocols, but could be essential for assays that are under development) • Is sampling (e.g., sample size per group; number of observations per endpoint) expected to be sufficient to detect differences across groups?	• NTP OHAT: could be incorporated into confidence in outcome characterization; timing of endpoint evaluation considered under applicability • SciRAP: negative controls considered under Tier 1 criteria; Tier II administration of test substance criteria and measurement/data collection criteria includes positive controls and appropriateness of the methods for the endpoints • SYRCLE: not explicitly considered (could be included in “other sources of bias”)
Exposure Number of concentrations or dose levels and their range, timing and duration of exposure	• Do the concentration/dose levels span a range in which effects can be expected to occur? • Is the timing and duration of exposure relevant for the endpoints under study? If the sensitive exposure window is unknown, is the exposure period wide enough to cover likely possibilities? • Is the route and method (e.g., gavage versus diet) of administration appropriate for the chemical and endpoint(s) being studied?	• NTP OHAT: dose, timing and route of of exposure considered under applicability • SciRAP: some elements considered under relevance criteria; others considered under Tier II test compound and administration of test substance criteria • SYRCLE: not explicitly considered (could be included in “other sources of bias”)
Analysis Statistical analysis and presentation (aspects that could obscure or exaggerate an effect)	• Does the presentation of the data fully and accurately represent the results (e.g., pooling across dose groups or sexes or related endpoints without justification)? • Are alternative analyses or displays that are likely to change the interpretation of the results (e.g., presenting continuous data as dichotomized)?	• NTP OHAT: not explicitly considered (could be included in “other sources of bias”) • SciRAP: considered under Tier II measurement/data collection criteria and statistics criteria • SYRCLE: not explicitly considered (could be included in “other sources of bias”)

NTP OHAT = National Toxicology Program Office of Health Assessment and Translation; SciRAP = Science in Risk Assessment and Policy; SYRCLE = SYstematic Review Centre for Laboratory animal Experimentation