“…From other sources we included four additional studies. In total, we included 28 studies in our main analysis ( De Lacey, Record & Wade, 1985 ; Lowry, 1985 ; Eichorn & Yankauer, 1987 ; Neihouse & Priske, 1989 ; Evans, Nadjari & Burchell, 1990 ; Hobma & Overbeke, 1992 ; Puttermann, 1992 ; Goldberg et al, 1993 ; George & Robbins, 1994 ; Hansen & McIntire, 1994 ; Warren et al, 1997 ; Schulmeister, 1998 ; Lawson & Fosker, 1999 ; Lee & Lee, 1999 ; Fenton et al, 2000 ; Pieters, Ceysens & De Heyn, 2001 ; Gosling, Cameron & Gibbons, 2004 ; Lukić et al, 2004 ; Buchan, Norris & Kuper, 2005 ; Gupta et al, 2005 ; Reddy et al, 2008 ; Al-Benna et al, 2009 ; Singh & Chaudhary, 2009 ; Awrey et al, 2010 ; Davids et al, 2010 ; Mertens & Baethge, 2011 ; Buijze et al, 2012 ; Luo et al, 2013 ) and three in an additional analysis (see Fig. 1 for PRISMA flowchart).…”