1. Selection bias (random sequence generation and allocation concealment)

For each included trial, we planned to categorise the risk of selection bias as:

2. Blinding (performance bias)

For each included trial, we planned to categorise the methods used to blind study personnel from knowledge of which intervention a participant received.

1. Low risk: no blinding or incomplete blinding, but review authors judge that the outcome is not likely to be influenced by lack of blinding; blinding of participants and key study personnel ensured; unlikely that blinding could have been broken.

2. High risk: no blinding or incomplete blinding, and the outcome is likely to be influenced by lack of blinding; blinding of key trial participants and personnel attempted, but likely that blinding could have been broken, and the outcome is likely to be influenced by lack of blinding.

3. Unclear risk: No or unclear information is provided.

3. Blinding (detection bias)

For each included trial, we planned to categorise the methods used to blind outcome assessors from knowledge of which intervention a participant received.

1. Low risk: no blinding or incomplete blinding, but review authors judge that the outcome is not likely to be influenced by lack of blinding; blinding of participants and key study personnel ensured; unlikely that blinding could have been broken.

2. High risk: no blinding of outcome assessment, but review authors judge that outcome measurement is not likely to be influenced by lack of blinding; blinding of outcome assessment; likely that the blinding could have been broken, and outcome measurement is likely to be influenced by lack of blinding.

3. Unclear risk: No or unclear information is provided.

4. Incomplete outcome data (attrition bias)

For each included trial and for each outcome, we planned to describe the completeness of data including attrition and exclusions from the analysis.

1. Low risk:

   1. No missing outcome data.

   2. Reasons for missing outcome data unlikely to be related to true outcome (for survival data, censoring unlikely to be introducing bias).

   3. Missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups.

   4. For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk is not enough to have a clinically relevant impact on the intervention effect estimate.

   5. For continuous outcome data, plausible effect size (difference in means or standardized difference in means) among missing outcomes is not enough to have a clinically relevant impact on observed effect size.

   6. Missing data have been imputed by appropriate methods.

2. High risk:

   1. Reasons for missing outcome data likely to be related to true outcome, with imbalance in numbers or reasons for missing data across intervention groups.

   2. For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk is enough to induce clinically relevant bias in intervention effect estimate.

   3. For continuous outcome data, plausible effect size (difference in means or standardized difference in means) among missing outcomes is enough to induce clinically relevant bias in observed effect size.

   4. "As‐treated" analysis done with substantial departure of the intervention received from that assigned at randomization.

   5. Potentially inappropriate application of simple imputation.

3. Unclear risk: No or unclear information is provided.

5. Selective reporting (reporting bias)

For each included trial, we planned to describe how we investigated the risk of selective outcome reporting bias and what we found. We planned to access all protocols of the included trials through a search of clinical trials registries (clinicaltrials.gov; controlled‐trials.com; and who.int/ictrp) and by direct contact with trial authors.

We planned to assess the methods as follows.

• Low risk: The study protocol is available, and all of the trial's prespecified (primary and secondary) outcomes of interest in the review have been reported in the prespecified way; or the study protocol is not available, but it is clear that published reports include all expected outcomes, including those that were prespecified (convincing text of this nature may be uncommon).

• High risk: Not all of the trial's prespecified primary outcomes have been reported; one or more primary outcomes are reported using measurements, analysis methods or subsets of the data (e.g. subscales) that were not prespecified; one or more reported primary outcomes were not prespecified (unless clear justification for their reporting is provided, such as an unexpected adverse effect); one or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta‐analysis; the study report fails to include results for a key outcome that would be expected to have been reported for such a trial.

• Unclear risk: No or unclear information is provided (the study protocol is not available).

6. Other potential sources of bias (other bias)

For each included trial, we planned to describe any important concerns that we had about other possible sources of bias (e.g. whether a potential source of bias is related to the specific study design used).

We planned to assess whether each trial was free of other problems that could put it at risk of bias as follows.

1. Low risk: The trial appears to be free of other sources of bias.

2. High risk: The trial has at least one important risk of bias (e.g. the trial had a potential source of bias related to the specific study design used or has been claimed to have been fraudulent or had some other problem).

3. Unclear risk: Risk of bias may be present, but information is insufficient for assessment of whether an important risk of bias exists, or rationale or evidence is insufficient to suggest that an identified problem will introduce bias.