Date	Event	Description
8 May 2013	New citation required but conclusions have not changed	Five new studies were included (Karagoz 2009; Kelemen 2007; Li‐Tsang 2010; Momeni 2009; Wigger‐Alberti 2009). Seven studies were excluded and we requested additional data from three authors (responses from two were received at the time of writing). The review authors’ conclusions remain unchanged.
8 May 2013	New search has been performed	Second update, new searches.