Date	Event	Description
8 September 2015	New search has been performed	The search has been updated to 22 May 2015. One new study was included in the review.
8 September 2015	New citation required and conclusions have changed	One study has been added to the review. The authors of the review have changed.
7 August 2015	Amended	A 'Published Note' has been added, with a change to the inclusion criteria. In the future, trials eligible for inclusion must have adequate allocation concealment.
15 October 2010	Amended	Reference corrected.
13 October 2009	New citation required but conclusions have not changed	The search was updated to April 1 2009. No new studies have been included. The conclusions remain the same. The authors of the review have changed.
27 March 2008	Amended	Converted to new review format.
12 April 2006	New search has been performed	The searches were updated in April 2006; no new studies for inclusion were identified.