Heard 1998.

Methods	Single‐centre RCT (USA)
Participants	Quote: "All patients who were admitted to the surgical intensive care units at the University of Massachusetts Medical Center from March 1994 through June 1995 and who needed a CVC were eligible for the study." The authors did not provide any exclusion criteria
Interventions	C‐SS‐impregnated CVCs versus non‐impregnated CVCs
Outcomes	Catheter colonization, CRBSI, use of antibiotics
Notes	Sources of funding: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	The study used an alternate form of allocation. Quote: "Randomization was based on the last digit of the medical record number: patients with an odd number received a standard uncoated CVC."
Allocation concealment (selection bias)	High risk	The study used an alternate form of allocation. Quote: "Randomization was based on the last digit of the medical record number: patients with an odd number received a standard uncoated CVC."
Blinding of participants and personnel (performance bias) All outcomes	High risk	There was no clear statement about blinding, although blinding appeared unlikely as the study and control catheters differed in appearance, and the authors did not report any measures taken to blind the personnel involved (for example: a transparent dressing was used to dress the catheters)
Blinding of outcome assessment (detection bias) Microbiological outcomes like catheter colonization	Unclear risk	It was unclear whether the microbiological outcome assessors were blinded
Blinding of outcome assessment (detection bias) Clinical outcomes like CRBSI	High risk	There was no clear statement about blinding, although blinding appeared unlikely as the study and control catheters differed in appearance, and the authors did not report any measures taken to blind the personnel involved (for example: a transparent dressing was used to dress the catheters)
Incomplete outcome data (attrition bias) All outcomes	High risk	308/351 catheters (87.7%) were analyzed. However some of the reasons for excluding the participants (detailed below) appeared dubious (for example, exchanged with other catheters and transferred to other unit), as some or all of the outcomes could still have been assessed. Quote: "Fifty seven catheters were removed or exchanged with other catheters and not cultured because the patient was transferred to a rehabilitation facility with the catheter in place or the patient had been transferred to a different area of the hospital (e.g., operating room or ward) and the intensive care unit team was not notified that the catheter was being removed."
Selective reporting (reporting bias)	Low risk	All the outcomes specified in the Methods, including CRBSI, catheter colonization and the use of antibiotics, were reported in the Results
Other bias	Low risk	None identified