Date	Event	Description
5 October 2010	Amended	Contact details updated.
2 July 2009	Amended	Revision to the risk of bias characteristic of included studies.
2 February 2009	New search has been performed	Review updated. No new studies. Conclusions not changed.
16 October 2008	Amended	Converted to new review format.
23 July 2006	New citation required and conclusions have changed	Substantive amendment.
29 October 2005	Amended	New studies found and included or excluded.
18 October 2005	Amended	New studies sought but none found.
1 October 2005	New search has been performed	Minor update.