Date	Event	Description
27 June 2011	New search has been performed	Searches updated. No new trials fulfilled our inclusion criteria. We excluded 38 new trials (Bantia 2010; Boltz 2010; Brammer 2009; Burch 2009; Cady 2011; Carter 2008; Cayley 2010; Chawla 2009; Chen 2007; Cheng 2009; Choi 2009; Chou 2008; Cowling 2008; Curran 2010; De la Camara 2007; DeLaney 2010; Falagas 2010; Farlow 2008; Fiore 2008; Guo 2007; Hota 2007; Kalia 2008; Kim 2011; Kirkby 2010; Korenke 2008; Langlet 2009; Matheson 2007; Miyachi 2011; Moffat 2008; Morrison 2007; Nuesch 2007; Sato 2008; Simeonova 2009; Tappenden 2009; Thomas 2008; Wailoo 2008; Welton 2008; Whitley 2007).
29 April 2011	New citation required but conclusions have not changed	Our conclusions remain unchanged.
13 May 2009	Amended	No changes ‐ republished to fix technical problem.
12 June 2008	Feedback has been incorporated	Feedback comment added.
25 May 2008	Amended	Converted to new review format.
26 July 2007	New search has been performed	Searches conducted.