Study	Reason for exclusion
Alvim 2005	1. Randomisation unclear 2. Interventions not relevant 3. Outcomes not relevant
Beiter Jr 2001	1. Study not RCT or quasi‐RCT 2. Interventions not relevant
Charache 1981	1. Study not RCT or quasi‐RCT 2. Interventions not relevant
Charache 1983	1. Study not RCT or quasi‐RCT 2. Interventions not relevant
de Araujo 1994	1. Group allocation not clear (contacted authors several times for clarification, but to date have received no reply)
Gonzalez 1988	1. Interventions not relevant
Gonzalez 1991	1. Study not RCT or quasi‐RCT 2. Interventions not relevant
Guy 1971	1. Study not RCT or quasi‐RCT 2. Interventions not relevant
Guy 1973	1. Study not RCT or quasi‐RCT
Hardwick Jr 1999	1. Interventions not relevant
Hatch 1965	1. Study not RCT or quasi‐RCT 2. Interventions not relevant
Kalinyak 2005	1. Participants not relevant 2. Interventions not relevant
Nalbandian 1971	1. Study not RCT or quasi‐RCT 2. Interventions not relevant
Orringer 2001	1. Interventions not relevant
Oski 1965	1. Study not RCT or quasi‐RCT 2. Interventions not relevant
Rhodes 1974	1. Interventions not relevant

RCT: randomised controlled trial