Dettenkofer 2010.

Methods	Multicentre RCT (Switzerland) Study period: May 2002 to June 2005 Setting: 2 haematology units and 1 surgical unit in 2 university hospitals
Participants	Adult patients who required a CVC. Number of participants: 400 Number of catheters; 400 Age: median age of 59 years (25% quartile of 48 to 70 years) Sex: 66% male overall
Interventions	2‐arm comparison of skin antisepsis prior to catheter insertion. Intervention A: 0.1% octenidine with 30% I‐propanol plus 45% 2‐propanol. Intervention B: 74% ethanol with 10% 2‐propanol.
Outcomes	Catheter colonisation Skin colonisation Catheter‐related BSI Adverse events Outcomes assessed at various points during in‐patient stay.
Notes	The unit of analysis was patient, and it appeared that 1 catheter per patient was analysed although this was not stated explicitly. Funding source: the study was funded partly by the Swiss National Science Foundation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	'Methods', 'Randomisation and interventions': "The randomisation code was produced by the independent Centre for Clinical Studies using computerised random number generator… used a stratification factor and block randomisation with randomly varying block length"
Allocation concealment (selection bias)	Low risk	'Methods', 'Randomisation and interventions': As above, and "The randomisation was realised using closed envelopes, ensuring that the sequence was concealed before patients entered the trial."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	'Methods', 'Randomisation and interventions': "The patients, staff administering the intervention, the microbiology lab were all blinded to the assignment."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	'Methods', 'Randomisation and interventions': "The patients, staff administering the intervention, the microbiology lab were all blinded to the assignment"
Incomplete outcome data (attrition bias) All outcomes	High risk	Discussion, paragraph 2: "20% of the catheters were not cultured, however they were equally distributed". The absolute rate of post randomisation exclusion was high for the outcome of catheter colonisation. However, the authors appeared to follow the intention‐to‐treat principle as they analysed the patients for whom the data was available in the originally assigned group.
Selective reporting (reporting bias)	Low risk	Authors reported all 4 major outcomes as stated in the 'Methods', namely, catheter colonisation, skin colonisation, catheter‐related BSI and adverse effects in sufficient detail in the 'Results'.
Other bias	Low risk	None identified