The SILVER (Silver Impregnated Line Versus EVD Randomized trial): a double-blind, prospective, randomized, controlled trial of an intervention to reduce the rate of external ventricular drain infection.
BACKGROUND
Cerebrospinal fluid (CSF) infections associated with external ventricular drain (EVD) placement attract major consequences. Silver impregnation of catheters attempts to reduce infection.


OBJECTIVE
To assess the efficacy of silver catheters against CSF infection.


METHODS
We performed a randomized, controlled trial involving 2 neurosurgical centers (June 2005 to September 2009). A total of 356 patients requiring an EVD were assessed for eligibility; 325 patients were enrolled and randomized (167 plain, 158 silver); 278 patients were analyzed (140 plain, 138 silver). The primary outcome measure was CSF infection as defined by organisms seen on Gram stain or isolated by culture. Secondary outcome measures included ventriculoperitoneal (VP) shunting.


RESULTS
There was a significant difference in infection risk between the 2 study arms: 21.4% (30/140) for plain catheters vs 12.3% (17/138) for silver catheters (P = .0427; 95% confidence interval [CI]: 1.015-3.713). Patients who had an EVD infection had more than double the risk of requiring a VP shunt compared with patients without an EVD infection (45.7% [21/46] vs 19.7% [45/229], respectively, P = .0002; 95% CI: 1.766-6.682). There was also a significant difference in VP shunt risk with infection: plain (55.2%; 16/29) vs the silver arm (29.4%; 5/17); P = .0244 (95% CI: 1.144-11.695). A multivariate analysis demonstrated that infection risk was increased by duration of EVD placement (odds ratio: 1.160), spontaneous intracranial hemorrhage (odds ratio 4.958) and decreased by silver catheters (odds ratio: 0.423).


CONCLUSIONS
The study provides Class I evidence that silver-impregnated catheters reduce CSF infection.
Academic Neurosurgery Division, Department of Clinical Neurosciences, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom. nk330@cam.ac.uk
Nicole Chwee Har
NC
Keong
Diederik Olivier
DO
Bulters
Hugh K
HK
Richards
Mark
M
Farrington
Owen C
OC
Sparrow
John D
JD
Pickard
Peter J
PJ
Hutchinson
Peter J
PJ
Kirkpatrick
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002552:Cerebral Ventricles / Q000601:surgery*; D002557:Cerebrospinal Fluid Shunts / Q000295:instrumentation* / Q000706:statistics & numerical data; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000627:therapeutic use; D015897:Comorbidity; D004311:Double-Blind Method; D004322:Drainage / Q000295:instrumentation / Q000706:statistics & numerical data; D004660:Encephalitis / Q000453:epidemiology* / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D016459:Prosthesis-Related Infections / Q000453:epidemiology* / Q000517:prevention & control*; D012307:Risk Factors; D012834:Silver / Q000737:chemistry / Q000627:therapeutic use*; D016896:Treatment Outcome; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
D020099:Coated Materials, Biocompatible; D012834:Silver