Date	Event	Description
31 August 2014	New citation required but conclusions have not changed	Review updated. No new trials identified so conclusions remain unchanged.
31 August 2014	New search has been performed	Search updated, no further trials identified. Methods updated. Please note that blinding has now been divided into two assessments: 1. Blinding of participants and personnel (performance bias); and 2. Blinding of outcome assessors (detection bias). Tables have been updated. A 'Summary of findings' table has been incorporated for this update.
12 October 2012	Amended	The Acknowledgements section has been edited.
18 July 2012	New citation required but conclusions have not changed	No new trials identified.
18 July 2012	New search has been performed	New search for trials conducted and Background updated.
31 August 2008	New search has been performed	Search updated. No new studies identified.
3 April 2008	Amended	Converted to new review format.
30 June 2007	New search has been performed	Search updated. No new trials identified.
31 August 2005	New search has been performed	Search updated. No new trials identified.
3 April 2004	Amended	Substantive amendment.