Bias Domains and Questions	Study designs
	Randomised controlled trials	Non‐randomised controlled trials	Randomised non‐controlled trials	Non‐randomised non‐controlled trials	Prospective observational studies	Retrospective studies
Appraisal of internal validity The ability of a study to provide an unbiased estimate of the true value of the parameter(s) that the study is intended to estimate.
SELECTION BIAS
1. Was administered dose or exposure level adequately randomised?	X		X
2. Was allocation to study groups adequately concealed?	X		X
3. Did selection of study participants result in appropriate comparison groups?		X		X	X	X
CONFOUNDING BIAS
4. Did the study design or analysis account for important confounding and modifying variables of the outcome? Were the confounding and modifying variables measured reliably and consistently?	X	X	X	X	X	X
PERFORMANCE BIAS
5. Were the research personnel and human subjects blinded to the study group during the study considering the health‐outcome ‘failure to thrive’?	X	X	X	X
ATTRITION / EXCLUSION BIAS
6. Were outcome data complete without attrition or exclusion from analysis?	X	X	X	X	X
DETECTION BIAS
7. Can we be confident in the exposure characterisation?	X	X	X	X	X	X
8. Can we be confident in the outcome assessment considering the outcome?	X	X	X	X	X	X
SELECTIVE REPORTING BIAS
9. Were all measured outcomes reported when considering the outcome?	X	X	X	X	X	X
OTHER SOURCES OF BIAS
10. Are there no other potential threats to internal validity (e.g. statistical methods were appropriate and researchers adhered to the study protocol)?	X	X	X	X	X	X

Adapted from OHAT/NTP risk of bias tool (https://ntp.niehs.nih.gov/ntp/ohat/pubs/riskofbiastool_508.pdf).