Yousefshahi 2013.

Methods	Single‐centre RCT (Iran) Study period: not reported. Setting: cardiac‐surgical ICU
Participants	Adult patients admitted to ICU after cardiac surgery Number of participants: 249 Number of catheters; 249 Age: mean age of 57 and 60 years (range 51 to 68) (reported separately in two groups) Sex: 76.1% and 76.5% male (reported separately in two groups)
Interventions	Skin antisepsis prior to CVC insertion. Intervention A: Sanosil (which consisted of hydrogen peroxide and silver). Intervention B: pure water (as adjunct to chlorhexidine 2% bath plus povidone‐iodine 10% scrub).
Outcomes	Catheter colonisation Sepsis Outcomes assessed at various points during in‐patient stay.
Notes	The number of CVCs evaluated matched the number of participants. Funding source: not stated.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	From the authors' description, it appeared that an alternate sequence was used following an initial coin toss to determine the daily order of the grouping. 'Methods': "[A]ll the patients were separated into the intervention and control groups based on simple randomisation and entry sequence to the pre‐operation room. Each day, a simple coin randomisation technique was used to determine the group for the first patient and the spraying of pure water or Sanosil 2% on the catheter location (from the upper chest to the mandible). Subsequently, odd and even numbers were used to determine the group of the other patients."
Allocation concealment (selection bias)	High risk	From the authors' description, it appeared that an alternate sequence was used following an initial coin toss to determine the daily order of the grouping. 'Methods': "[A]ll the patients were separated into the intervention and control groups based on simple randomisation and entry sequence to the pre‐operation room. Each day, a simple coin randomisation technique was used to determine the group for the first patient and the spraying of pure water or Sanosil 2% on the catheter location (from the upper chest to the mandible). Subsequently, odd and even numbers were used to determine the group of the other patients."
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	From the authors' description, it appeared that the patients and the person who removed the catheters to send for culture were blinded (see below). However, the authors did not state whether the nurse who sprayed the study substance was blinded to the study materials. 'Methods': "Both spray bottles were similar in shape and cover. Sanosil does not have any colour or smell and is similar to water, and the patients were blinded to the study." 'Methods': "Each day, two trained ICU nurses, blinded to the group type of the patients, collected the tips of five removed catheters aseptically..."
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	It appeared that all patients recruited initially had their CVCs analysed.
Selective reporting (reporting bias)	Low risk	Authors reported the 2 key outcomes specified in the 'Methods', namely, catheter colonisation and sepsis, in the 'Results'. As no patient in either group developed sepsis, we did not include this outcome in our meta‐analysis.
Other bias	Low risk	None identified

AC: arterial catheter; BSI: bloodstream infection; CHG: chlorhexidine‐gluconate; CVC: central venous catheter; ICU: intensive care unit; PA: pulmonary artery; RCT: randomised controlled trial.