Table 1. Eligible sources of bias in randomized trials.

Type of bias	Possible methodological features that can lead to bias
A. Bias arising from the randomisation process	Inadequate generation of a random sequence
	Inadequate allocation concealment
	Imbalance in baseline characteristics
	No adjustment for confounding in the analysis
B. Bias due to deviations from intended interventions	Non-blinded participants
	Non-blinded clinician/treatment provider
	Unbalanced delivery of additional interventions or co-interventions
	Participants switching interventions within the trial and being analysed in a group different from the one to which they were randomized
C. Bias due to missing/incomplete outcome	Missing/incomplete outcome data (dropouts, losses to follow-up, or post-randomisation exclusions)
D. Bias in measurement of outcomes	Non-blinded outcome assessor
	Non-blinded data analyst
	Use of faulty measurement instruments (with low validity and reliability)
E. Bias in selection of the reported result	Selective reporting of a subset of outcome domains, or of a subset of outcome measures or analyses for a particular outcome domain.