Pereira 1990.

Methods	Randomised controlled cross‐over trial (Latin square design ‐ participants took part in each of 4 interventions) Generation of random number sequence: no details given Allocation concealment: no details given Blinding: no details given A priori sample calculations: no Antisepsis protocol: yes Withdrawals: 2 participants withdrew Intention‐to‐treat analysis: no Clear inclusion or exclusion criteria: no
Participants	34 anaesthetic, recovery and ward nurses Baseline comparability: gender, age, ethnicity, hand dominance, baseline bacterial counts
Interventions	Group 1 ‐ 5 min initial scrub and 3 min subsequent scrub using chlorhexidine Group 2 ‐ 3 min initial and 30 s subsequent scrub using chlorhexidine Group 3 ‐ 5 min initial and 3 min subsequent scrub using povidone iodine Group 4 ‐ 3 min initial and 30 s subsequent scrub using povidone iodine
Outcomes	Outcome measure: CFUs on participants' hands Method of testing: glove juice method Timing of testing: before antisepsis, immediately after antisepsis, 2 h after initial antisepsis, 2 h after subsequent antisepsis
Notes	Participants did not take part in any surgical procedures
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Subjects were randomly assigned to one of four groups, and each group was assigned to one of the four scrub regimens each week. Control on the treatment order was achieved through a Latin square design, as described by Winder." Comment: adequate evidence of an appropriate study design, but on balance not enough evidence of truly random sequence generation
Allocation concealment (selection bias)	Unclear risk	Quote: "Subjects were randomly assigned to one of four groups, and each group was assigned to one of the four scrub regimens each week. Control on the treatment order was achieved through a Latin square design, as described by Winder."   Comment: no indication that allocation to each group was concealed to the personnel
Blinding (performance bias and detection bias) All outcomes ‐ Blinding participants	Unclear risk	Quote: "Subjects were randomly assigned to one of four groups, and each group was assigned to one of the four scrub regimens each week . . . Subjects were supervised by the investigator while they scrubbed on all test occasions."   Comment: no evidence to suggest that there was appropriate blinding of participants or personnel during the study
Blinding (performance bias and detection bias) All outcomes ‐ Blinding care givers	Unclear risk	Quote: "Subjects were randomly assigned to one of four groups, and each group was assigned to one of the four scrub regimens each week . . . Subjects were supervised by the investigator while they scrubbed on all test occasions."   Comment: no evidence to suggest that there was appropriate blinding of participants or personnel during the study
Blinding (performance bias and detection bias) All outcomes ‐ Blinding outcome assessors	Unclear risk	Bacterial contamination Quote: "While the glove was still on the hand, a sample of the fluid was taken . . . [S]amples were collected on four occasions for each condition: (1) immediately before scrubbing (both hands), (2) immediately after the initial surgical scrub (non‐dominant hand only) (3) 2 hours after the initial surgical scrub, immediately before the consecutive scrub (dominant hand) and (4) 2 hours after one consecutive surgical scrub (dominant hand)."   Comment: no indication that those collecting the samples, administering the fluid or those performing the microbial assays were in any way blinded to the intervention or protocol
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Thirty‐six subjects were recruited, but two subjects withdrew from the experiment before completing all four treatments (scrubs) because of skin reactions, including erythema, burning sensations and local swelling"   Comment: adequate evidence that losses to follow‐up were small and fully accounted for
Selective reporting (reporting bias)	Low risk	No direct quotes, but the results of each 'scrub' are displayed fully at baseline and subsequent time intervals in the Results as laid out in the Methodology.
Other bias	Unclear risk	Although the trial had a cross‐over design, it did not appear that this was reflected in the analysis.