Date	Event	Description
29 September 2008	Amended	Converted to new review format.
11 June 2004	New search has been performed	Two minor corrections have been made: the data from the Prasad trial on deaths were inadvertently omitted from the published review (now included); there was an error in the denominators used for the Muir trial (now corrected). An additional outcome (death or DVT) was added and the results section edited accordingly. The overall conclusions of the review were not altered.