Sebold 1993.

Methods	Study design: randomised controlled trial Object of randomisation: operations
Participants	US Surgeons performing major joint arthroplasty Number studied: 284 gloves inner or outer gloves (71 operations) Intervention 1: n = 100; Intervention 2: n = 96; control group: n = 88
Interventions	1) Double gloving with thicker glove (orthopaedic outer gloves and latex inner gloves) Control group was double latex gloves 2) Triple gloving with latex outer gloves, cloth middle gloves and latex inner gloves Control group 1 was double latex gloved; control group 2 was double gloving with thicker glove
Outcomes	Outcome: number of inner glove perforations per total number of inner gloves Perforation detection: the gloves were filled with water and perforations were noted as a jet of water Secondary outcome: self detection of glove perforations
Notes	Double versus double: Sebold 1993; triple versus double Sebold 1993
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation	Low risk	Cards indicating glove type in envelopes, sealed and shuffled, numbered from 1 to 75
Allocation concealment	Low risk	Envelopes sealed until beginning of OP
Blinding of study subjects	Low risk	Not possible; knowledge about the gloving method judged as having a low risk of changing the outcome
Blinding of outcome assessor	Unclear risk	Not reported
Incomplete outcome data (attrition bias)	Low risk	3 out of 25 cases in control excluded; 1 out of 25 in cloth glove group excluded
Selective outcome reporting (reporting bias)	Low risk	Perforations reported for inner, outer, changed gloves
Outcome measure (combined air and water test used?)	High risk	Water test only