Review Articles
The efficacy of silver alloy-coated urinary catheters in preventing urinary tract infection: a meta-analysis

https://doi.org/10.1016/S0002-9343(98)00240-XGet rights and content

Abstract

Purpose: Indwelling urinary catheters are implicated in most cases of nosocomial urinary tract infection. Silver-coating of catheters may reduce the risk of these infections; however, trials have provided mixed results. We performed a meta-analysis to estimate the effectiveness of silver-coated urinary catheters.

Subjects and methods: Published or unpublished articles were sought using MEDLINE, reference review, and correspondence with original authors, catheter manufacturers, and experts. Trials using silver-coated urinary catheters in the treatment group and uncoated urinary catheters in the control group were included. Bacteriuria, as evaluated by urine culture, was the outcome variable used to indicate urinary tract infection. Summary odds ratios (OR) and 95% confidence intervals (CI) were calculated using Mantel-Haenszel methods with a fixed-effects model.

Results: Of 117 reports retrieved, eight trials with a total of 2,355 patients satisfied inclusion criteria. The summary OR for urinary tract infection was 0.59 (95% CI, 0.42 to 0.84) indicating a significant benefit in the patients receiving silver-coated catheters. A test of heterogeneity, however, indicated that the odds ratios varied significantly among studies. Silver alloy catheters (OR = 0.24; 95% CI, 0.11 to 0.52) were significantly more protective against bacteriuria than silver oxide catheters (OR = 0.79; 95% CI, 0.56 to 1.10).

Conclusions: This meta-analysis clarifies discrepant results among trials of silver-coated urinary catheters by revealing that silver alloy catheters are significantly more effective in preventing urinary tract infections than are silver oxide catheters. Though silver alloy urinary catheters cost about $6 more than standard urinary catheters, they may be worth the extra cost since catheter-related infection is a common cause of nosocomial infection and bacteremia.

Section snippets

Literature review

The literature review began with a computerized search of the MEDLINE database (January 1, 1966, to January 31, 1997) using the exploded keywords “silver” and “catheter.” The search was not restricted to citations in the English-language literature. References in retrieved articles were also scanned, and original authors, catheter manufacturers, and experts were contacted to identify other published or unpublished reports.

We included trials that used a silver-coated urinary catheter in the

Results

The initial literature search identified 117 reports. Of these, 10 were clinical trials comparing silver-coated urinary catheters with noncoated urinary catheters. One trial was excluded because an open urinary collection system was used (25). Another was excluded because most of the patients were bacteriuric at baseline (26). Thus, eight trials 27, 28, 29, 30, 31, 32, 33, 34 with a total of 2,355 patients satisfied inclusion criteria for the meta-analysis (Table 1, Table 2).

The summary OR for

Discussion

Our meta-analysis helps to clarify discrepant results among trials of silver-coated urinary catheters and provides information on the type of catheter most useful in preventing nosocomial urinary tract infections. Much of the heterogeneity between studies appeared to be due to differences in catheter type and study design. Silver alloy catheters were effective in preventing bacteriuria whereas silver oxide catheters were not, possibly because silver alloy remains in the catheter for a longer

Acknowledgements

We thank Walter E. Stamm, MD, for his critical review of an earlier draft of the manuscript and Yuya Hirata for translating the Japanese studies into English. This work was completed while Dr. Saint was a Robert Wood Johnson Clinical Scholar.

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