Date	Event	Description
30 June 2015	New citation required but conclusions have not changed	Five new trials included, the conclusions remain unchanged.
30 June 2015	New search has been performed	Search updated. Five new trials included (Ahmadi 2011; Batista 2014; Chiu 2010; Kee 1989; Roberts 1998). One of these was previously excluded (Kee 1989) and one that was in 'Awaiting classification' has been included (Roberts 1998). Methods updated, four new outcomes added and the background has been revised. A 'Summary of findings' table has been added.
23 September 2008	Amended	Converted to new review format.