Date	Event	Description
1 September 2015	Amended	Minor edit to personal communication reference.
31 August 2015	New citation required but conclusions have not changed	Change to study selection criteria: removed quasi‐randomised controlled trials; reduced the intervention and follow‐up period from a minimum of three years to two years. New author team.
27 November 2014	New search has been performed	New search performed. No new studies identified.
8 August 2008	Amended	Converted to new review format.