Differences between protocol and review

[fixed, level 1 heading]

It is sometimes necessary to use different methods from those described in the original protocol. This could be because:

•  Methods for dealing with a particular issue had not been specified in the protocol;

• Methods in the protocol could not be applied (for example, due to insufficient data or a lack of information required to implement the methods);

• Methods are changed because a preferable alternative is discovered.

Some changes of methods from protocol to review are acceptable, but must be fully described in this section. The section provides a summary of the main changes in methods for the review over time. It should be used to:

• Point out any methods that were determined subsequent to the original published protocol (e.g. adding or changing outcomes; adding ‘Risk of bias’ or ‘Summary of findings’ tables);

• Summarize methods from the protocol that could not be implemented in the current review (e.g. because the review identified no eligible studies, or because no studies fell in a particular pre-defined subgroup);

• Explain any changes in methods from the protocol to the review, state when they were made and provide the rationale for the changes. Such changes should not be driven by findings on the effects of interventions. Consider the potential effect on the review’s conclusions of any changes in methods, and consider sensitivity analyses to assess this.