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Table 1 Description of tools used to assess risk of bias

From: Assessing risk of bias in human environmental epidemiology studies using three tools: different conclusions from different tools

Program or agency Tool Assessment process Domains assessed Number of questions Available answer options
NTP OHAT Risk of bias, internal validity Selection bias 1 Definitely low ROB; probably low ROB; probably high ROB; definitely high ROB
Confounding bias 1 Definitely low ROB; probably low ROB; probably high ROB; definitely high ROB
Attrition/exclusion bias 1 Definitely low ROB; probably low ROB; probably high ROB; definitely high ROB
Detection bias 2 Definitely low ROB; probably low ROB; probably high ROB; definitely high ROB
Selective bias reporting bias 1 Definitely low ROB; probably low ROB; probably high ROB; definitely high ROB
Other bias 1 Definitely low ROB; probably low ROB; probably high ROB; definitely high ROB
EPA IRIS Study evaluation Exposure measurement 1 Good; adequate; deficient; critically deficient
Outcome ascertainment 1 Good; adequate; deficient; critically deficient
Participant selection 1 Good; adequate; deficient; critically deficient
Confounding 1 Good; adequate; deficient; critically deficient
Analysis 1 Good; adequate; deficient; critically deficient
Selective reporting 1 Good; adequate; deficient
Sensitivity 1 Adequate; deficient
Overall study confidence 1 High; medium; low; uninformative
EPA TSCA Data quality criteria for epidemiological studies Study population 3 High; medium; low; unacceptable
Exposure characterization 3 High; medium; low; unacceptable
Outcome assessment 2 High; medium; low; unacceptable*
*Unacceptable not available for one question
Potential confounding/variable control 3 High; medium; low; unacceptable*
*High and unacceptable not available for one question
Analysis 4 High; medium; low; unacceptable*
*High and low not available for two questions
*High and unacceptable not available for two questions
Biomarker selection and measurement 7 High; medium; low; unacceptable
*High and unacceptable not available for one question
*Unacceptable not available for three questions
Overall study confidence 1 Sum of weighted scores/sum of metric weighting factor
UCSF Navigation Guide Risk of bias, internal validity Source population representation 1 Low; probably low; probably high; high
Blinding 1 Low; probably low; probably high; high
Exposure assessment 1 Low; probably low; probably high; high
Outcome assessment 1 Low; probably low; probably high; high
Incomplete outcome data 1 Low; probably low; probably high; high
Selective outcome reporting 1 Low; probably low; probably high; high
Confounding 1 Low; probably low; probably high; high
Conflicts of interest 1 Low; probably low; probably high; high
Other 1 Low; probably low; probably high; high
  1. Abbreviations: NTP National Toxicology Program, OHAT, Office of Health Assessment and Translation, EPA, Environmental Protection Agency, IRIS Integrated Risk Information System, TSCA Toxic Substances Control Act; ROB risk of bias, UCSF, University of California, San Francisco