How do I document protocol deviations in a review methods appendix?

Compare the registered protocol with the executed review, log each deviation with its date, reason, and impact, then append the register to the methods appendix. PRISMA 2020 asks reviewers to report the methods actually used, so the appendix should show what changed between the plan and the finished review.

Build the deviation register

1. Place the registered protocol and the executed methods side by side, then walk through each planned element in order: databases and sources, search strategy, eligibility criteria, selection process, and any planned synthesis. Record every element where the executed review differs, and mark the rest as unchanged so the comparison is complete.
2. For each deviation, enter four fields: the protocol element affected, the date the change was made, the reason for the change, and its impact on the review. State the impact concretely, such as studies that became eligible or ineligible, a search that returned different records, or a synthesis step that was adjusted.
3. Append the completed register to the methods appendix and cross-reference it from the methods text where the affected step is described, so a reader moving through the methods can see which steps changed and why.

What each field should contain

The protocol element identifies the specific planned step, such as a named database or a stated eligibility criterion. The date anchors the change to the review timeline. The reason explains the circumstance that prompted the change. The impact tells the reader what the change affected in the review's conduct or findings.

Cochrane guidance on searching and selecting studies describes documenting searches and managing records, which gives the register a natural place to capture changes to sources, strategies, and record handling. Keep the register in the same order as the methods so reviewers can check it against the protocol without hunting.

Keep it auditable

Write each entry as a factual record of what was planned, what was done, and when. A reader should be able to trace any changed step from the methods text to its register entry and back to the protocol.