Date	Event	Description
9 August 2017	Amended	This review has been withdrawn following Feedback from a group of readers who have identified possible errors in the analysis of data in the review. These concern handling of cross‐over and multi‐arm trials as well as corrections and clarifications of data used. This review has been withdrawn whilst these issues are addressed. Changes are also required to reflect current methodological standards. The review will be re‐published following updating, revision and peer review.
8 August 2017	Amended	This review has been withdrawn following correspondence from a reader who identified possible errors in the analysis of data in the review. These concern handling of cross‐over and multi‐arm trials as well as corrections and clarifications of data used. This review has been withdrawn whilst these issues are checked. Changes are also required to reflect current methodological standards. The review will be re‐published following updating, revision and peer review.
10 September 2014	New citation required but conclusions have not changed	Added 17 new studies in this update. Risk of bias was re‐assessed of all the included trials as per current recommendation.
10 September 2014	New search has been performed	Added 17 new studies in this update. Risk of bias was re‐assessed of all the included trlas as per current recommendation.
22 August 2007	New citation required and conclusions have changed	Substantive amendment