Langgartner 2004.

Methods	Single‐centre RCT (Germany) Study period: May 1999 to August 2002. Setting: Inpatient hospital wards and ICUs
Participants	'Materials and methods': "Adult inpatients scheduled for elective CVC placement during normal working hours were eligible for participation in the study. Patients from normal wards as well as from the intensive care units were included. Patients known to be allergic to iodine or chlorhexidine were excluded as were all patients who needed a CVC placed under emergency conditions. No underlying disease was defined as an exclusion criteria." Number of participants: 119 Number of catheters: 200 (140 analysed) Age: mean age ranged from 50.5 to 56.6 years (SD ranged from 14.8 to 17.2 years)(reported separately according to three groups). Sex: overall 60.7% male.
Interventions	Skin disinfection prior to catheter insertion and daily during the change of dressings with 1 of the 3 regimens. Intervention A: povidone‐iodine 10% aqueous solution. Intervention B: propanol 70%/chlorhexidine 0.5%. Intervention C: propanol 70%/chlorhexidine 0.5% followed by PVP‐iodine 10%. Outcomes assessed at various points during in‐patient stay.
Outcomes	Catheter colonisation
Notes	Funding source: not stated.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported
Allocation concealment (selection bias)	Low risk	'Materials and methods': "Sealed and numbered envelopes contained the randomisation code together with the instructions for skin disinfection and forms for the documentation of the procedure."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of patients and carers not reported, although blinding appeared very unlikely because the number of antiseptic solution used for each group and their appearances were different.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	It was not stated whether the personnel taking the swabs and the interpreter of the microbiological tests were blinded to the allocation.
Incomplete outcome data (attrition bias) All outcomes	High risk	'Materials and methods': "In addition to the 140 catheters evaluated, 60 more catheters had been included but had to be excluded from analysis: in 5 cases, patients had died with the catheter in place, in 38 cases microbiological analysis of the catheter tip had not been performed and 17 catheters were lost during follow‐up (e.g. the patient was taken to a different clinic with the CVC in place).” In total, 200 catheters were recruited but only 140 were evaluated, which represented an overall dropout rate of 30%. It was unclear why trialists did not perform microbiological analyses in the 38 catheters as mentioned. 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)	High risk	The only outcome stated in the 'Methods' and reported was catheter colonisation. Some important outcomes such as catheter‐related blood stream infection, clinical sepsis and mortality were not reported.
Other bias	High risk	There was a unit of analysis issue in which the number of catheters analysed exceeded the number of participants by nearly 18%, and the outcome was reported using catheters as the units.