Date	Event	Description
13 August 2008	New citation required but conclusions have not changed	New search was conducted with the addition of new studies. Structural changes were also made to the results tables.
26 July 2007	New search has been performed	This review has been updated (new search June 2007) from a previously published review (Wager 2003). The following studies were added: Technical editing (14 new studies, making a total of 32 studies). New studies: Dupuy 2003; Fister 2005; Harbourt 1995; Hartley 1996a; Hartley 1996b; Hartley 1996c; Hartley 2000; Hartley 2002; Hartley 2003; Khosrotehrani 2002; Siegel 2005; Silagy 1998; Wilczynski 1995; Wong 2005 Reference accuracy (31 new studies, making a total of 66 studies). New studies: Acea Nebril 1997; Aronsky 2005; Browne 2004; Buchan 2005; Cakir 2003; Celayir 2003; Ferreira 2000; Gosling 2004; Gupta 2005; Jackson 2003*; Lawson 1999; Lok 2001; Lukic 2004; Ngan Kee 1997b; Nishina 1995f; Nishina 2000*; Nuckles 1993; O'Connor 2002; Oermann 2001; Oermann 2002a; Oermann 2002b*; Oermann 2002c; Orlin 1996; Perez Garcia 2000; Pieters 2001; Pulida 1995; Riesenberg 2001; Siebers 2001; Sutherland 2000; Vargas‐Origel 2001; Warren 1997 * = reference accuracy studies also included in technical editing section Some structural changes were made to the results tables.