Platt 1990.

Methods	Study: multicenter, prospective, randomised. Allocation: computer. Blinding: yes.
Participants	612 patients: 301 P / 311 C.
Interventions	Herniorrhaphy ATB: cefonicid 1 g IV. MA: 90 minutes before surgery. Control: placebo.
Outcomes	IP= 4; IC= 6
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer generated list. in blocks of 10.
Allocation concealment (selection bias)	Low risk	Probably yes.
Blinding (performance bias and detection bias) All outcomes	Low risk	Quote: "Cefonicid and placebo were supplied in identical numbered vials. The treatment codes were not known by anyone at the participating centres, unless the sealed, opaque label attached to each vial was opened". Comment: Yes.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: " None of the personnel at the data processing or coordinating center knew the treatment codes, and the codes were not revealed to the patients or medical personnel until the last one completed the evaluation." Comment: Yes
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Yes