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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Comparison of utility of blood cultures from intravascular catheters and peripheral veins: a systematic review and decision analysis

ME Falagas, MS Kazantzi, and IA Bliziotis.

Review published: 2008.

Link to full article: [Journal publisher]

CRD summary

This study concluded that for various patient populations who had an intravascular catheter, the results offered support for the drawing of at least one blood culture from the intravascular catheter when clinically indicated. Given the limitations of the included studies and the review, the conclusions should be treated with some caution.

Authors' objectives

To compare the diagnostic accuracy of blood cultures obtained from intravascular catheters and peripheral veins.

Searching

PubMED and Cochrane Central Register of Controlled Trials were searched from 1970 to October 2005 for studies published in English; search terms were reported. Bibliographies of retrieved articles were also searched.

Study selection

Retrospective and prospective studies of the accuracy of bacteraemia diagnosis from blood cultures drawn from central venous, peripheral arterial or Swan-Ganz catheters compared to standard peripheral venipuncture in patients with suspected bacteraemia were eligible for inclusion if they reported sufficient data to calculate or extract diagnostic outcomes and clearly defined true bacteraemia. Case-control studies, case series and case reports were excluded. Most of the participants in the included studies were in intensive care units. The type and site of catheters from which blood was drawn varied across studies, as did the preparation of catheters and skin prior to sampling and the method used to determine bacteraemia. Two reviewers independently selected studies for the review.

Assessment of study quality

The authors did not state that validity was assessed. The lag time between tests and the discarding of the initial portion of the blood sample were reported.

Data extraction

Sensitivity, specificity and positive and negative predictive values were extracted or calculated for each study. Two reviewers independently extracted data.

Methods of synthesis

Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated for sensitivity, specificity, positive predictive values and negative predictive values using a fixed-effect and random-effects models. The findings of the fixed-effect model were used where no statistically significant heterogeneity was observed. The method used to test for heterogeneity was not reported. Pooled results were used to draw a decision analysis tree to illustrate the numbers that were treated appropriately and inappropriately.

Results of the review

Six studies were included: three retrospective (2,013 paired blood cultures) and three prospective (664 paired blood cultures). The lag time between the paired tests ranged from simultaneous sampling to four hours. All prospective samples discarded the initial blood drawn. Blood volume ranged from 3 mL to 10 mL.

Culture obtained from intravascular catheters had statistically significant better sensitivity (OR 1.85, 95% CI: 1.14, 2.99, range of sensitivities was 82.4 per cent to 94.8 per cent for central vascular catheters and 64.4 per cent to 95.4 per cent for peripheral venipuncture) and improved, but not statistically significantly so, negative predictive values (OR 1.55, 95% CI: 0.999, 2.39, range of negative predictive values was 97.6 per cent to 99.0 per cent for central vascular catheters and 95.5 per cent to 99.1 per cent for peripheral venipuncture) for diagnosing bacteraemia than peripheral venipuncture. Results from a fixed-effect model were reported.

Specificity was significantly lower when cultures were obtained from intravascular catheters (OR 0.33, 95% CI: 0.18, 0.59, range of specificities was 80.6 per cent to 95.6 per cent for central vascular catheters and 95.9 per cent to 98.4 per cent for peripheral venipuncture) as was positive predictive value (OR 0.41, 95% CI: 0.23, 0.76, range of positive predictive values was 17.2 per cent to 63.9 per cent for central vascular catheters and 66.7 per cent to 85.4 per cent for peripheral venipuncture).

Results from a random-effects model were reported. Results for the tests for heterogeneity were not reported. A decision analysis tree was presented to illustrate the numbers that would be appropriately and inappropriately treated if 1,000 blood cultures were sampled. The analysis tree showed that for every one additional patient diagnosed with true bacteraemia using blood drawn from intravascular catheters, more than seven would receive antibiotics inappropriately.

Authors' conclusions

For various patient populations who have an intravascular catheter, the results offered support for the drawing of at least one blood culture from the intravascular catheter when clinically indicated.

CRD commentary

The review addressed a clear review question with appropriate inclusion criteria. Only two sources were searched. No specific attempts to locate unpublished data were made. Inclusion was restricted to English-language articles. Therefore, publication and language bias could not be ruled out. Study selection and data extraction were conducted in duplicate. It seemed that the quality of the included studies was not systematically assessed, although some aspects of quality for this type of study were presented. The reference standard used in some studies was concordant results from the two tests, resulting in incorporation bias; this may have increased the the degree of agreement between the two tests. Half of the studies were retrospective in design and, therefore, had a lower level of evidence. Pooled estimates of the standard diagnostic outcomes extracted were not calculated, nor were the likelihood ratios or diagnostic odds ratios. Instead, odds ratios for each of the standard outcomes were calculated. It was unclear why the data were presented in this manner. Given the limitations of the included studies and the review, the conclusions should be treated with some caution.

Implications of the review for practice and research

The authors did not state implications for practice or research.

Funding

Not stated.

Bibliographic details

Falagas M E, Kazantzi M S, Bliziotis I A. Comparison of utility of blood cultures from intravascular catheters and peripheral veins: a systematic review and decision analysis. Journal of Medical Microbiology 2008; 57(Part 1): 1-8. [PubMed: 18065660]

Indexing Status

Subject indexing assigned by NLM

MeSH

Bacteremia /complications /diagnosis /drug therapy; Blood /microbiology; Blood Specimen Collection /standards; Catheterization, Central Venous /standards; Catheters, Indwelling /adverse effects /microbiology; Decision Making; Humans

AccessionNumber

12008103638

Database entry date

08/07/2009

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 18065660

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