General comments: The protocol addresses an important topic relevant to clinicians, policy makers and methodologists. The authors have substantial expertise in the area. The publication of the protocol will allow the transparent evaluation of the methods employed in the development of the guidelines, and strengthen the final guidelines, and as such should be published.

Major comments: While I am sympathetic to the idea that there are specific considerations when undertaking a systematic review in children’s health, I think the case for a paediatric specific reporting guideline would be strengthened by an example of how the use of PRISMA may fail researchers undertaking a review relevant to children. Are there particular challenges that the authors have experienced that would help to explain the value of a specific reporting guideline? There are no details from the as yet unpublished scoping review by the same authors, nor from the Toronto meeting. Some elucidation of the paediatric-specific items identified there may help to illustrate the need for the extension of PRISMA.

The methods appear robust and clear. I would question the inclusion of the systematic review within the Phase III consensus process. Would this not be a part of the earlier Phase II literature review, as per the Moher paper cited?

Minor comments: Page 2, line 39 “sough” should read “sought” Background: The references used to demonstrate the methodological limitations of systematic reviews seem somewhat arbitrary, and following a statement that ends “even…in high impact journals” cite research that was not published in high impact journals. Would it not make sense to use some of the evidence base which prompted the development of the PRISMA guidelines which the authors go on to describe?

Final sentence of the background “improve the quantity” would presumably read better as “increase the quantity” if that is itself a worthwhile objective.

Methods: In the systematic review process (page 7, line 40), does the ‘conventional approach’ not refer to the PRISMA approach? Similarly, line 47, the description of PRISMA as a ‘widely endorsed reporting guideline’ is unnecessary. PRISMA has already been introduced. Page 7, line 37, complied should be compiled. Page 9, line 9, will the systematic reviewers used to evaluate the extension have been involved in the Delphi or the Consensus meeting?