Date	Event	Description
14 November 2012	New citation required but conclusions have not changed	One trial added to ongoing studies (CTRI/2008/091/000157).
30 September 2012	New search has been performed	Format of review updated, including background format, methods, and results and discussion format. Characteristics of studies and 'Risk of bias' tables updated. Search updated and one report identified.
10 November 2008	Amended	Contact details updated.
6 March 2008	Amended	Converted to new review format.
26 June 2007	New search has been performed	Search updated. No new trials identified.
30 April 2004	New search has been performed	No new studies found in current update. One paper placed in 'excluded studies' (plan for a trial unlikely to proceed). Odds ratio changed to relative risk. Text expanded (e.g. 'Background').
31 August 2000	New search has been performed	New search for trials conducted but none found.
21 January 1999	New search has been performed	Search updated.