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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-.

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

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Does thromboelastography predict postoperative thromboembolic events? A systematic review of the literature

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Review published: .

CRD summary

The predictive accuracy of thromboelastography for postoperative thromboembolic events was highly variable and further prospective studies were required. Overall, the authors' conclusions seem reasonable given the poor-quality available data.

Authors' objectives

To systematically review the accuracy of thromboelastography as a predictor of postoperative thromboembolic events in adult surgical patients.

Searching

PUBMED and EMBASE were searched between 1980 and February 2008 without language restrictions. Search terms were reported. References of included studies/reviews were scanned.

Study selection

Prospective clinical studies of adult patients who underwent surgery and had thromboelastography (TEG) tests performed perioperatively to detect hypercoagulability were included in this review. Reference standards for the detection of thromboembolic events considered for this review were: venography, compression ultrasound and Doppler imaging or I125-labelled fibrinogen uptake tests.

The primary outcome of interest was pulmonary embolism confirmed by autopsy, ventilation/perfusion scanning or pulmonary computed tomography angiography. Secondary outcomes included myocardial infarction, ischaemic stroke and vascular graft occlusion (all to be confirmed by named tests).

Included studies were either prospective cohort or randomised controlled trials. Mean age of the patients ranged from 36 to 82 years, where reported. The ratio of male to female varied considerably between studies. Most patients underwent surgery with general anaesthetic. Most studies evaluated deep vein thrombosis as a secondary outcome; all thromboembolic events were confirmed by at least one reference test. Most studies followed patients for at least one week. Six studies used a TEG device manufactured by one particular company. There was no consensus on definitions of hypercoagulability; six of the studies included maximum amplitude as the main criteria.

Two reviewers independently performed the study selection. Disagreements were discussed to reach consensus.

Assessment of study quality

Study quality was assessed using published criteria including items on: spectrum of cases; blinded interpretation of test results; patient selection; details of the test; study design; differential and partial verification bias; and details of the population. An overall quality score was produced (range of possible values not reported).

The authors did not report how many reviewers performed the validity assessment.

Data extraction

Data were extracted to construct a 2x2 table for each study. If a cell within a table contained 0, 0.5 was added to the cells. Sensitivity, specificity, positive and negative likelihood ratios and diagnostic odds ratio (DOR) were calculated for each included study; 95% confidence intervals were calculated for DORs.

Two reviewers independently performed data extraction. Authors were contacted for missing data where possible.

Methods of synthesis

This review adopted a narrative approach to synthesis as a result of variation in definitions of hypercoagulability, TEG methodology, patient characteristics, reference standards used and choice of outcome measures. It was felt to be inappropriate to pool the results using a ROC curve; diagnostic odds ratios and associated 95% confidence intervals (CI) were converted to an equivalent area under the curve to allow qualitative assessment of TEG accuracy.

Results of the review

Ten studies (n=1,056) were included in this review. One study was an RCT that provided cohort type data (n=100). Study quality scores ranged from 3 to 7. Investigators in most studies were not blinded. Sufficient details on the TEG or reference test were not provided in most studies. Five studies reported on measures of test accuracy and five studies compared mean values of TEG parameters in diseased versus normal patients.

Five studies reported on prognostic accuracy (n=461) and reported the range for sensitivity as 0% to 100% and range for specificity as 62% to 92%. Positive likelihood ratios ranged from 1.43 to 7.67. Negative likelihood ratios ranged from 0.28 to 0.96.

The ratio of odds to detect a hypercoagulable state by TEG in a patient with a thromboembolic event compared with a patient without a thromboembolic complication ranged from 1.5 to 27.7.

Authors' conclusions

The predictive accuracy of TEG for postoperative thromboembolic events was highly variable. Further prospective studies were required to determine if TEG was a clinically useful screening tool for high-risk surgical populations.

CRD commentary

This review addressed a clear question with defined inclusion criteria. The searches were adequate, but they did not address grey literature and this potentially introduced publication bias. Searches, study selection and data extraction were reported as being carried out in duplicate, which reduced the risk of reviewer error and bias. Included studies were quality assessed and this information was taken into account within the narrative synthesis. A summary score was not particularly informative, but sufficient additional information was provided. Overall, the authors' conclusions seem reasonable given the poor-quality available data.

Implications of the review for practice and research

Practice: The authors did not state any implications for practice.

Research: The authors stated that high-quality controlled cohort studies that assessed performance of TEG as a predictor of thromboembolic events were needed to determine whether TEG was a clinically useful screening test.

Funding

Not stated.

Bibliographic details

Dai Y, Lee A, Critchley LA, White PF. Does thromboelastography predict postoperative thromboembolic events? A systematic review of the literature Anesthesia and Analgesia 2009; 108(3): 734-742. [PubMed: 19224777]

Indexing Status

Subject indexing assigned by NLM

MeSH

Blood Coagulation Disorders /blood /diagnosis; Clinical Trials Data Monitoring Committees; Databases, Factual; Humans; Postoperative Complications /blood /diagnosis; Predictive Value of Tests; Randomized Controlled Trials as Topic /standards; Reference Standards; Risk Assessment; Thrombelastography; Treatment Outcome

AccessionNumber

12009104585

Database entry date

31/03/2010

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.

Copyright © 2014 University of York.
Bookshelf ID: NBK77265

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