Date	Event	Description
22 June 2008	Amended	Converted to new review format.
12 November 2007	New search has been performed	In the 2007 update, one new study was included and six new studies were excluded. After integrating the data from the new included study, no significant changes were noted in all comparisons evaluated. Our conclusions and recommendations for further research remain unchanged.
20 January 2005	New search has been performed	Searches conducted.