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Quantitative: Quantitative: Quantitative: Quantitative: Quantitative: Quantitative: Quantitative:
APA/Mech. Title/Abstract Introduction
Method
Results
Discussion Glob. Issues
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Quantitative Critique
Megan Spicer
Lees-McRae College
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Quantitative Critique
Central venous catheters and arterio-venous fistulas and grafts (AVFs and AVGs) are
vascular access devices that allow hemodialysis to occur in patients with end-stage renal disease.
Of these vascular accesses, central venous catheters have the highest rate of infection at nine
times that of AVFs and five times the rate of AVGs (Lincoln, 2011, p. 411). The article
“Antimicrobial Lock Solutions for the Prevention of Infections Associated with Intravascular
Catheters in Patients Undergoing Hemodialysis: Systematic Review and Meta-analysis of
Randomized, Controlled Trials” assesses whether antimicrobial lock solutions in central venous
catheters decreases the risk of bloodstream infections (Yahav et. al, 2008, p. 83). By
systematically reviewing previous randomized, controlled studies Yahav et al. (2008) analyzes
the benefits of these catheter lock solutions and tries to come to a consensus on catheter lock
solutions in clinical practice.
Title & Abstract
Title
“Antimicrobial lock solutions for the prevention of infections associated with
intravascular catheters in patients undergoing hemodialysis: Systematic review and metaanalysis of randomized, controlled trials” succinctly indicates the independent variable- use of
antimicrobial lock solutions- and the dependent variable- presence of infections associated with
intravascular catheters. The study population is patients undergoing hemodialysis.
Abstract
The abstract summarizes the background of the problem which is catheter-related
bloodstream infection in the population of people that are hemodialysis dependent. Methods used
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to assess outcomes are a systematic review and meta-analysis of randomized, controlled trials of
single or combination antimicrobial catheter lock solutions. The results of the meta-analysis are
that eleven trials that included antibiotic lock solutions verses five trials that assessed nonantibiotic antimicrobial lock solutions were included. Conclusions taken from the studies were
that antibiotic catheter lock solutions reduce catheter-related bloodstream infections.
Introduction
Statement of Problem
Yahav et al’s (2008) study states the problem in the background as well as in the first
paragraphs of the study report. The problem stated is central venous catheter-related bloodstream
infection. It is noted that these infections are ‘an important cause of morbidity and mortality
among patients undergoing dialysis’, and is in fact the second leading cause of death in end-stage
renal disease (p.83). Because of this, prevention of these infections is vitally important. Although
antimicrobial lock solutions have been the topic of several trials, there is no consensus in clinical
practice. Because there is no consensus, the study makes a persuasive argument for the need of a
systematic review and meta-analysis of randomized control trials to find out whether or not these
antimicrobial lock solutions are in fact efficacious and whether they will decrease infection rates
in this population. If there can be a consensus regarding lock solutions, then nursing clinical
practice will be affected because antimicrobial lock solutions should become common clinical
practice.
Purpose/Questions/Hypothesis
The purpose of this study is to test an intervention- antimicrobial lock solutions- on
reducing central venous catheter-related bloodstream infections. Specifically it is a systematic
review of all previous studies related to antimicrobial lock solutions for patients on hemodialysis.
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The purpose included the independent variable, antimicrobial lock solutions, and the dependent
variable, central venous catheter-related bloodstream infections.
The research question proposed is that the incidence of dialysis catheter-related
bloodstream infections to date can be positively affected by antimicrobial lock solutions,
however, this intervention has lacked consensus due to questions on which antimicrobial to use
and whether or not antibiotic resistance will occur.
Literature Review
This article was published in May 2008 and included primary source articles from 1986
to 2006. The article does not synthesize the research on this problem, but states the purposes of
the included articles.
Conceptual/Theoretical Framework
Yahav et. al (2008) used schematic models to represent the flowchart for the selections of
trials (p. 85). Schematic models are visual representations of relationships between phenomena
and concepts (Polit, 2010, p.197). Mantel-Haenszel fixed-effects model was used to perform
meta-analysis (Yahav et. al, 2008, p.84).
Method
Protection of Participants Rights
The procedures to safeguard study participants were not disclosed because it was a metaanalysis of previous articles. The individual articles address these rights.
Research Design
This experimental design was a meta-analysis of randomized, controlled trials. The
design was post-test only. The article only analyzed previous articles dealing with interventions
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based on presence or absence of catheter-lock solutions, and was not designed to test specific
antimicrobials. Quality was assessed through sensitivity analysis.
Setting/Population/Sample
The populations assessed were hemodialysis patients with central venous catheters.
Samples included randomized, controlled trials that assessed adults and children and up to 30%
of the participants could include acute renal failure diagnosis. Specific settings for each article
were not noted in this meta-analysis. All patients had a single or combination antimicrobial lock
solution. Patients were grouped from eleven trials that assessed antibiotic catheter lock solutions
verses five trials that assessed non-antimicrobial catheter lock solutions. The sample size was
adequate with 924 patients in the catheter-lock solution group vs. 661 patients in the nonantimicrobial catheter lock solution group.
Data Collection and Measurement
The independent variable was adequately defined as patients that had the intervention of
antimicrobial catheter-lock solutions. The dependent variable was therefore the presence or
absence of catheter-related bloodstream infections. The dependent variable was measured by
clinically significant bacteremia, catheter-related bloodstream infections, and removal of the
catheter for any cause. Secondary measurements of the dependent variable included any exit-site
infections, tunnel infection, catheter thrombus, need for hospitalization, emergence of resistance,
fungal infections, all cause mortality.
Data was collected using a Cochrane filter for randomized, controlled trials selected by
two independent reviewers who applied inclusion criteria and extracted the data (Yahav et al,
2008, p.84)
Results
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Data Analysis
Relative risks with 95% CIs were calculated for individual trials and then meta-analysis
was performed using Mantel-Haenszel fixed-effects model (Yahav et al, 2008, p.84).
Yahav et. al (2008) states that an ‘x2 test for heterogeneity and the I 2 measure of
inconsistency’ was used to assess for heterogeneity.” Substantial heterogeneity (I 2 1 50%) was
investigated through subgroup analyses and metaregression (Comprehensive Meta-analysis 2.2)
for catheter tunneling and incident (90days) versus prevalent (longer-term) hemodialysis. A
funnel plot was visually inspected, and the small-studies effect was formally assessed using
Egger’s test of the intercept” (p.84).
Findings
Infection rates were assessed by pooling results from individual trials. Infection was assessed
based on relative risks with 95% confidence intervals (CIs). Meta-analysis using MantelHaesnzel fixed-effects model was performed. For antibiotic catheter lock solutions, catheterrelated bloodstream infections were reduced by 0.44 relative risk, 95%CI.
Tables included:
a) Catheter-related bloodstream infection per patient and catheter-days
b) Trials that compared any antibiotic catheter lock solution
c) Effects of study characteristics on the relative risk for bloodstream infections per
patient in studies with antibiotic lock vs. heparin alone
d) Funnel plots
Discussion
Interpretation of Findings
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All major findings are interpreted and discussed within the context of prior research
and/or the study’s conceptual framework and the interpretations are consistent with the results.
The study notes that catheter lock solutions should be used with additional measures such as
exit-site dressings and nasal decontamination with antibiotics. The study also notes that the size
of the effect (decreased bloodstream infections) varied significantly depending on the study, and
that development of antibiotic resistance has not been adequately assessed in these trials.
This study recognizes that the Centers for Disease Control and Prevention as well as the
Kidney Disease Outcomes Quality Initiative guidelines generally do not advocate for antibiotic
catheter lock solutions because of the fear of antibiotic resistance (Yahav et al, 2008, p.90).
Despite this, the study suggests that there is a statistically significant reduction in bloodstream
infections without antibiotic resistance.
Implications/Recommendations
The recommendation of this meta-analysis is that antibiotic catheter-lock solutions should
be considered in routine clinical practice with concurrent use of other infection prevention
strategies. This study recommends that this modality is best used to prevent the first episode of
bloodstream infection. Because of the threat of antibiotic resistance the recommendation is that
more research should be done in long-term studies.
Global Issues
Presentation
The report is well-written and organized in as much as it is easy to find topic headings
and navigate to areas of importance. The information for recommendations is accessible for
nurses wishing to find clinical implications of this topic. However, the limitations of the study
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are left at the end in a few sentences leading the reader to believe these limitations are not very
important, when in actuality the limitations skew the findings.
Summary Assessment
This article appears valid and the results appear truthful. Antibiotic catheter lock
solutions appear to have a valid place in reducing cases of catheter-related bloodstream infection
and, if used, have meaningful implications for clinical practice. However, the possibility of
antibiotic resistance is enough of a possibility that it warrants more study and may in fact negate
the positive findings of these studies.
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References
Lincoln, M. (2011). Preventing catheter-associated bloodstream infections in hemodialysis
centers: The facility perspective. Nephrology Nursing Journal, 38, 411-415.
Polit, D. F. & Beck, C. T. (2010). Nursing research: Appraising evidence for nursing practice
(7th ed.). Philadelphia, PA: Lippincott, Williams, & Wilkins.
Yahav, D., Rozen-Zvi, B., Gafter-Gvili, A., Leibovici, L., Gafter, U., Paul, M. (2008).
Antimicrobial lock solutions for the prevention of infections associated with intravascular
catheters in patients undergoing hemodialysis: Systematic review and meta-analysis of
randomized control trials. Clinical Infectious Diseases, 47(1), 83-93.