Sometimes updating your review results in new outcomes or comparisons being added. If this is the case, your original data extraction forms may need to be altered or extended, and piloted again. If this is the case, it might be necessary to go back to the original included trials and check that they did not include any information relevant to this new outcome or comparison.
Another possible update to a review is more methodological. As systematic review methodology advances, and the techniques available in RevMan are extended, it may be possible to perform additional analyses or strengthen existing ones not available in an earlier version of your review.
There is variability between review groups about when and if your updated review should again go through the process of editorial review. If your update involves no further analysis or change of result, it may not need to be refereed, however if there are new analyses and changes to conclusion, the same pre-publication process that was followed for your original review is likely to be repeated. You will need to check with your review group regarding their editorial policy for updated reviews.
If the update of your review leads to changes in your conclusions that you and your review group decide are important enough that anyone who read the review in the past should read it again, you should mark the review as ‘Conclusions changed’ in the ‘What’s New’ section of your review in RevMan.
Sometimes a search of the new evidence reveals there is no need to update your review. If this is the case, you should still update the date of the search strategy and indicate in the What's New section of your review that a search has been done, resulting in no additions or changes to your review.