Date	Event	Description
24 June 2013	New citation required but conclusions have not changed	Substantive amendment. New authorship. New methods. 2 new included studies. Conclusions not changed.
24 June 2013	New search has been performed	Search updated to June 2013.
2 May 2008	New search has been performed	Search updated to January 2008.
2 May 2008	Amended	Converted to new review format.
2 May 2008	New citation required and conclusions have changed	Substantive amendment. Title was modified. 2 randomised controlled trials were included. The conclusions changed.