Date	Event	Description
17 February 2009	Amended	Source of support amended
8 October 2008	New search has been performed	Updated for issue 1, 2009 with 9 new studies. Relapse prevention studies were removed, as now covered in another review.
16 February 2005	New citation required and minor changes	Updated for issue 2, 2005 with 4 new studies. No changes to the main conclusions.
22 May 2002	New citation required and minor changes	Updated for issue 3, 2002, expanding the inclusion criteria to include trials comparing more than one variant or type of group based programme. No changes to the main conclusions.