Date	Event	Description
15 February 2012	New citation required but conclusions have not changed	No new studies found
3 February 2012	New search has been performed	As no new studies are likely, this review can now be considered to be stable.
3 November 2008	New citation required but conclusions have not changed	Relevant references to the argument were added. Trial data were included. No new studies were included. Risk of bias was re‐examined.
1 April 2008	Amended	Converted to new review format.
10 July 2006	New citation required and conclusions have changed	Substantive amendment