Date	Event	Description
8 August 2012	New search has been performed	Review updated August 2012. Seven new studies in this update (Balakier 2009; Fang 2010; Ge 2008; Germond 2004; Hagemann 2010; Kutlu 2010; and Valojerdi 2010).
8 August 2012	New citation required but conclusions have not changed	Seven new studies added; no change to conclusions.
17 June 2008	New search has been performed	New search identified four new randomised controlled trials, which have been added. Conclusions have not changed.
15 May 2008	Amended	Converted to new review format.
18 September 2007	New citation required and conclusions have changed	Substantive amendment