Table 2.

Risk of bias assessment table

Bias domain	Bias item	Review authors judgment (adequate, inadequate or unclear)
Selection bias	Sequence generation	Sequence generation will be regarded as adequate if a random approach in the sequence generation process—referred to as a random number table, a random computer-generated number, coin tossing, drawing of lots, shuffling cards or throwing dice–is described. Date of inclusion or admission, or record number of clinic/hospital will be considered inadequate. Deficient information about the process will be considered as unclear
	Allocation concealment	Allocation concealment will be regarded as adequate if sequentially numbered, sealed, opaque envelops, numbered or coded medical containers or a centralised randomisation is applied. If it is possible to predict the assignment, allocation concealment will be regarded as inadequate. Therefore, date of birth, application of an open random allocation schedule, or any other explicitly unconcealed procedure will be regarded as inadequate. The allocation concealment will be regarded as unclear if the method of concealment is not available
Performance bias	Blinding of participants	Blinding of patients will be regarded as adequate if intervention and control treatment are described as indistinguishable, or if it is unlikely that the blinding could have been broken for both patients and data collectors. Deficient information about the blinding process will be considered as unclear
Detection bias	Blinding of key study personnel	Blinding of key study personnel will be regarded as adequate if intervention and control treatment are described as indistinguishable, or if it is unlikely that the blinding could have been broken for data collectors and key study personnel. Deficient information about the blinding process will be considered as unclear
Attrition bias	Incomplete outcome data	Data will be regarded as adequate (complete) if there are no missing outcome data or if the missing data constitute less than 10% of total number of participants at baseline and if no differences in reasons for dropout were observed between the groups. Further, outcome data will be considered adequate if missing data have been imputed using appropriate statistical methods like intention to treat (ITT). Deficient information about the blinding process will be regarded as unclear
Other bias	Centre status	A trial will be considered a multicentre trial if more than one centre is involved. In case of missing information, the trial will be classified as multicentre if it reports both several ethics committees and different affiliations of authors. If the report stated both a single ethics committee and a single author affiliation, the trial will be classified as a single centre. Information about single- and multicentre trials will be extracted from the text, statements, author's affiliations, and acknowledgement in every included trial
	Trial size	To judge whether a trial is small or large, we will use a threshold of 128 participants. If the total number of randomised participants is less than 128 patients (according to the Cochrane review), the study will be regarded as a small trial; trials with ≥128 participants will be referred to as large trials. The threshold of 64 participants in each group corresponds to a reasonable power (80%) to detect a standardised mean difference (SMD) ≥ 0.534
	Funding	Trials will be specified either as being funded by for-profit funding or non-profit funding. Non-profit funding includes money received from both non-profit organisations (eg, Internal hospital funding and governmental funding) and not funded trials. For-profit organisations will be defined as companies that might acquire financial gain or loss depending on the outcome of the trial. Further, trials with a mix of for-profit and non-profit or if the funding is not reported, will be considered as for-profit funded. Funding is defined as including provision of manpower (authorship, statistical analysis or other assistance), study materials (drug, placebo, assay kits or similar materials), or grants.27 Sources of funding will be extracted from the text, statements of sources of support, authors’ affiliations, acknowledgments and trial registration, if available