Study	Reason for exclusion
Anonymous 1991	Not randomised
Anraku 2006	Review (to be clarified)
Bychkov 2001	Wrong intervention
Candel 2009	Review
Clemente 2013	Review
Coolen 1995	Retrospective
Crisci 1989	Not randomised
Cui 1994	Retrospective
Davis 1993	Not randomised
de Antonio 2006	Not randomised
Dusmet 2004	Review
Eguchi 1988	Review
Eichhorn 1975	Wrong intervention
Elias 1993	Wrong intervention
Friedberg 2012	Review
Fujimori 1997	Wrong study design
Fujimura 2001	Review
Gatzemeier 1986	Not randomised
Graham 1993	Review
Grants 1989	Not randomised
Greschuchna 1978	Retrospective
Gridelli 1994	Not randomised
Gridelli 1994a	Not randomised
Hansen 1984	Review
Hara 1988	Retrospective
Hara 1991a	Not randomised
Hara 1991b	Retrospective
Ju 2012	Retrospective
Karrer 1978	Review
Karrer 1982a	Review
Karrer 1982b	Duplicate
Karrer 1986	Review
Karrer 1987	Wrong intervention
Karrer 1988	Wrong intervention
Karrer 1989a	Wrong intervention
Karrer 1989b	Duplicate
Karrer 1990	Wrong intervention
Karrer 1995	Wrong intervention
Kobayashi 1988	Not randomised
Kodama 1998	Review
Krishnamurthy 2011	Not randomised
Lad 1991	Duplicate
Lad 1994b	Duplicate
Lagerwaard 2010	Wrong participant population
Lassen 1999	Review
Lewinski 2001	Not randomised
Lexer 1988	Not randomised
Li 2010	Not randomised
Lucchi 1997	Retrospective
Lukianski 1988	Not randomised
Macchiarini 1989a	Retrospective
Macchiarini 1989b	Duplicate
Namikawa 1988	Not randomised
Osterlind 1986a	Wrong intervention
Osterlind 1986b	Not randomised
Prager 1984	Not randomised
Rea 1998	Wrong intervention
Schamanek 1994	Wrong intervention
Shepherd 1983	Retrospective
Shepherd 1989	Retrospective
Shepherd 1991	Not randomised
Sorenson 1981	Review
Szczesny 2003	Review
Theuer 1992	Review
Tsuchiya 2005	Wrong intervention
Ulsperger 1990	Duplicate
Ulsperger 1991	Duplicate
Veronesi 2007	Not randomised
Watanabe 1988	Not randomised
Yamaguchi 1988	Not randomised