Date	Event	Description
20 October 2020	New citation required but conclusions have not changed	No new included studies identified
20 October 2020	New search has been performed	Four new studies excluded. No change in conclusions
7 September 2018	New citation required and conclusions have changed	New studies added; SOF tables included
7 September 2018	New search has been performed	Six new studies added. Conclusions changed.
7 February 2012	Amended	Search strategies & search methods updated
12 May 2009	New citation required but conclusions have not changed	Author list updated
31 March 2009	Amended	Two new studies added, no change to conclusions
13 October 2008	Amended	Converted to new review format.
30 November 2005	New citation required and conclusions have changed	Substantive amendment