Criteria abstracted from The Users' Guide to Medical Literature, from the Health Information Research Unit and Clinical Epidemiology and Biostatistics, McMaster University

Highlighted lines and questions below provide links to the pertinent description of criteria in The EBM User's Guide, now available at the Canadian Centres for Health Evidence

Article Reviewed:

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Efficacy of Antiseptic-Impregnated Central Venous Catheters in Preventing Catheter-Related Bloodstream Infection: A Meta- analysis

Veenstra DL, Saint S, Saha S, Lumley T, Sullivan SD.

JAMA;1999;281:261-267.. [abstract] [full-text for a limited time]

Reviewed by M. Kathleen Moynihan Hardart, MD, Children's Hospital, Boston

Review posted August 21, 2000

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I. Are the results of the study valid?

A. Primary questions:

1. Did the overview address a focused clinical question?

Yes. The meta-analysis focused on the efficacy of chlorhexidine- silver sulfadiazine-impregnated catheters (AIC) for the prevention of nosocomial catheter colonization (CC) and catheter-related bloodstream infection (CR-BSI).

2. Were the criteria used to select articles for inclusion appropriate?

Yes. The overview specifically included only randomized, controlled clinical trials using chlorhexidine-silver sulfadiazine- impregnated catheters in the treatment group and standard catheters in the control group. Studies had to have sufficient data to calculate effect size. Exceptions were made in that studies with quasi-randomized design (randomization by patient record number) were included in the main analysis. Studies that did not initially provide adequate information were included if that information was subsequently obtainable from the authors.

Furthermore, to be considered in the meta-analysis, studies had to define as outcome, incidence of CC or CR-BSI. Strict definitions of CC and CR-BSI were maintained. CC required documentation of growth from a catheter segment by quantitative or semi-quantitative culture techniques. CR-BSI was defined as isolation of the same organism from blood and catheter cultures using semi-quantitative or quantitative culture techniques with or without clinical signs of systemic infection or lack of evidence of other sources of infection.

B. Secondary questions:

3. Is it unlikely that important, relevant studies were missed?

Yes. The meta-analysis evaluated the results of a MEDLINE search of articles published from January 1966 to January 1998 in any  language using the keywords "chlorhexidine", "antiseptic", and "catheter". The reference lists of the articles were evaluated, as were review articles on the subject. Additionally, the manufacturer of the AIC's and the authors of the articles were contacted for additional sources of information.

A total of 215 articles were located from all sources. No unpublished studies were found. Thirteen studies in total met criteria for inclusion in the meta-analysis. Twelve studies were used in the analysis of CC and eleven studies were used in the analysis of CR-BSI.

4. Was the validity of the included studies appraised?

Yes. Each study included in the meta-analysis met strict criteria as a randomized controlled study with specific study objectives and strict outcome definitions. Furthermore, each study included in the meta-analysis was evaluated for the following methodologic components: appropriateness of randomization, extent of blinding, and description of eligible subjects.

5. Were assessments of studies reproducible?

Yes. Data extraction was conducted blindly and independently by two of the authors. A third author resolved any discrepancies between the abstractors.

6. Were the results similar from study to study?

Yes. The studies included in the meta-analysis evaluated similar outcomes, looking at CC and/or CR-BSI as defined above. All studies considered in the meta-analysis favored treatment groups over controls for both CC and CR-BSI. Tests for heterogeneity were performed using the Woolf method.

While the individual studies provided strong statistical evidence of the efficacy of AIC's in preventing CC, the test for heterogeneity of treatment effect for catheter colonization among the studies was positive. This was thought by the authors to be mainly the effect of the inclusion of one study which had atypically low criteria for a positive catheter culture and which evaluated a primarily immunocompromised patient population.

All eleven studies evaluating the efficacy of AIC's at reducing CR-BSI demonstrated reduction in the odds of contracting a CR-BSI with AIC's, although only one demonstrated statistical significance. There was no evidence of heterogeneity among the odds ratios of those studies evaluating efficacy of AIC's reducing CR-BSI.

II. What are the results?

1. What are the overall results of the review?

The summary results of the twelve studies evaluating catheter colonization reflect a statistically significant reduction in the odds of CC in the group treated with AIC's. (OR= 0.44, 95% CI 0.36-0.54, p < 0.001). There was no obvious association of study OR's with duration of catheter placement.

The summary results of the eleven studies evaluating CR-BSI reflect a statistically significant reduction in the odds of CR-BSI in the group treated with AIC's. (OR= 0.56, 95% CI 0.37-0.84, p=0.005). There was no obvious association of study OR's with duration of catheter placement.

Overall, the meta-analysis suggests that AIC's are effective at reducing both the incidence of CC and CR-BSI when compared with non-impregnated catheters. The use of AIC's results in an approximately 40% decrease in the development of CR-BSI.

2. How precise were the results?

Both the meta-analysis and sensitivity analyses suggest a significant decrease in the odds of CC and CR-BSI with the use of AIC's with all confidence intervals for odds ratio estimates favoring treatment. With a 95% CI of 0.36-0.54, the odds of reducing CC with AIC's are at least 46% and may be as great as 64%. The odds of reducing CR-BSI with AIC's are at least 16% and could be as great as 63% with the 95% CI of 0.37-0.84.

A reduction in the odds of CC and CR-BSI with AIC's was still present with (1) increasing the variance of the 5 studies with more than one catheter per patient, randomized per patient (2) excluding the three trials randomized by patient record number (3) analyzing the studies that used triple lumen catheters exclusively (4) evaluating the trials that used only semi-quantitative culture methods (5) evaluating only the seven studies that required clinical symptoms for the diagnosis of CR-BSI or in which blood cultures were only drawn if clinical symptoms were present.

III. Will the results help me in caring for my patients?

1. Can the results be applied to my patient care?

The patient population were patients at high risk for catheter related infections. One third were in the ICU, and in 2 studies the patients were those receiving TPN. The remaining patients were from a variety of hospital settings including some immunocompromised patients. The mean duration of treatment ranged 5.1 to 11.2 days. Our patient population in the ICU is similarly at high risk for catheter related infections. The biggest difference is the age of the patient population. Pediatric patients may be less likely to develop catheter related infection due to differences in bacterial colonization patterns and sites of  catheter placement. A lower probability of infection may lower the degree of reduction in CR-BSI associated with AIC's.

2. Were all clinically important outcomes considered?

The goal of the study was to evaluate the reduction of catheter colonization and or catheter-related blood stream infections through the use of antiseptic-impregnated catheters. This goal was accomplished in the meta-analysis. While an attempt was made to comment on the association between duration of catheter placement and reduction of CC and CR-BSI, no clear trend was noted.

3. Are the benefits worth the harms and costs?

This study did not evaluate the risk/benefit ratio of the antiseptic-related catheters, nor did it examine the cost ratio. However, in a subsequent publication by the same authors, AIC's were determined to be cost effective with a net savings of $196.00 per catheter when considering the cost of a CR-BSI. The assessment also determined that for every 300 AIC's used, $59,000 will be saved, 7 cases if CR-BSI avoided and one death prevented. In the current study, no adverse events were noted with use of the treatment catheters.

References

1. Veenstra et al. Cost-effectiveness of antiseptic-impregnated central venous catheters for the prevention of catheter-related bloodstream infection. JAMA. 1999; 282:554-560. [abstract] [full-text for a limited time]
   • PedsCCM EB Journal Club Review by M. K. Moynihan Hardart

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