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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].

Mechanical compression versus subcutaneous heparin therapy in postoperative and posttrauma patients: a systematic review and meta-analysis

RW Eppsteiner, JJ Shin, J Johnson, and RM van Dam.

Review published: 2010.

Link to full article: [Journal publisher]

CRD summary

This review found that the risk of thromboembolic disease was similar for mechanical compression and heparin, but heparin was associated with a greater risk of bleeding in postsurgical/post-trauma patients. These conclusions are supported by the data, but should be interpreted with some caution due to the possibility of publication bias and lack of details on some aspects of trial quality.

Authors' objectives

To determine the impact of mechanical compression compared with subcutaneous heparin on venous thromboembolic disease and post-treatment bleeding in postsurgical and post-trauma patients.

Searching

PubMed and EMBASE were searched from inception to November 2008. Search terms were reported. Reference lists of included studies and relevant reviews were screened. Experts in the area were contacted to identify additional relevant studies, including unpublished data. The review was restricted to studies published in English.

Study selection

Randomised controlled trials (RCTs) that compared prophylaxis with mechanical compression versus subcutaneous heparin in patients undergoing surgery or admitted immediately post-trauma were eligible for inclusion. Trials had to that report data on deep vein thrombosis, pulmonary embolism or bleeding. Trials that evaluated heparin in combination with other agents were excluded.

The primary outcome measure was the proportion of patients who developed deep vein thrombosis. Secondary outcome measures were incidence of pulmonary embolism and incidence of bleeding complications.

Most of the included trials used a single modality for compression including pneumatic calf/thigh compression, foot pump, or graduated compression stockings; two trials used dual-modality compression using combinations of these. Heparin was administered subcutaneously in unfractionated or low molecular weight form. The mean age of participants was from 42 to 71 years (where reported), with a range of 18 to 93 years.

The authors did not state how many reviewers selected studies for inclusion.

Assessment of study quality

Two reviewers independently assessed trials according to the following criteria: blinding of outcome measurement, treatment compliance, withdrawals, and use of an intention-to-treat analysis.

Data extraction

Two reviewers independently extracted data to calculate relative risks (RRs) together with 95% confidence intervals (CIs). Standard errors were calculated according to the probability functions of the binomial distribution.

Methods of synthesis

DerSimonian and Laird random-effects models were used to estimate summary relative risks together with 95% confidence intervals. Heterogeneity was assessed using I2.

Subgroup analyses were carried out using stratified analysis and meta-regression. Subgroups investigated included type of compressive device, type of heparin, type of bleeding reported, and type of patient/surgery. Sensitivity analysis was conducted to investigate the effect of individual studies on summary estimates by excluding each trial one at a time from the meta-analysis.

Publication bias was assessed using funnel plots and the Begg and Egger tests.

Results of the review

Sixteen RCTs were included in the review (n=3,887 participants). Six trials reported that the person interpreting the deep vein thrombosis screening imaging was blinded to treatment; it was not possible to blind patients or care givers. Randomisation resulted in equal distribution of confounding factors in all trials. Duration of follow-up ranged from five days to three months.

There was no significant difference in the risk of deep vein thrombosis (16 RCTs) or pulmonary embolism (15 studies) between patients who received mechanical compression compared with those who received subcutaneous heparin. There was substantial heterogeneity for deep vein thrombosis (I2=62%), but not for pulmonary embolism (I2=0%).

The type of heparin (unfractionated or low molecular weight) was the only factor significantly associated with risk of deep vein thrombosis in the meta-regression analysis (p=0.03). The risk of deep vein thrombosis was significantly increased with mechanical compression compared to low molecular weight heparin (RR 1.80, 95% CI 1.16 to 2.79; eight RCTs), but not compared with unfractionated heparin (eight RCTs). None of the other variables investigated in the meta-regression analyses modified the effect on deep vein thrombosis risk. As trials were homogeneous for pulmonary embolism, subgroup analysis was not conducted.

The risk of bleeding was significantly reduced in patients who received mechanical compression compared with those who received subcutaneous heparin (RR 0.46, 95% CI 0.31 to 0.70; 10 RCTs). There was some evidence of heterogeneity (I2=42%). When analysed by type of bleeding, results were significantly lower for mechanical compression for major bleeding, minor bleeding, and the risk of undergoing transfusion. When results were stratified by heparin type, the risk of bleeding was significantly increased for both unfractionated and low molecular weight heparin; none of them modified the effect on bleeding risk in the meta-regression analysis. None of the individual trials were found to substantially alter the pooled estimates.

There was no evidence of publication bias (p>0.2).

Authors' conclusions

The overall bleeding risk profile favoured the use of mechanical compression over subcutaneous heparin; the benefits of venous thromboembolic disease prophylaxis was similar between groups.

CRD commentary

This review addressed a focused objective supported by clearly defined inclusion criteria. The literature search was adequate, but the restriction of the review to studies published in English raised the possibility of language and publication bias. Appropriate steps were taken to minimise bias and errors when extracting data and assessing quality, but it was unclear whether such steps were taken when selecting studies for inclusion.

Although some relevant quality-related features were assessed, a formal quality assessment was not conducted and important features, such as concealment of treatment allocation and methods of randomisation, were not considered. This made it difficult to assess the validity of the evidence. Appropriate methods were used to pool data including assessment and investigation of heterogeneity.

The authors' conclusions are supported by the data presented and are likely to be reliable, but should be interpreted with some caution due to the possibility of publication bias and lack of details on some aspects of trial quality.

Implications of the review for practice and research

Practice: The authors stated that the potential benefits of heparin should be carefully weighted against the increased risk of bleeding in the decision to use heparin rather than mechanical compression in postsurgical and post-trauma patients.

Research: The authors stated that future studies should assess whether low molecular weight heparin has a differential effect in certain patient subgroups.

Funding

Not stated.

Bibliographic details

Eppsteiner RW, Shin JJ, Johnson J, van Dam RM. Mechanical compression versus subcutaneous heparin therapy in postoperative and posttrauma patients: a systematic review and meta-analysis. World Journal of Surgery 2010; 34(1): 10-19. [PubMed: 20020289]

Indexing Status

Subject indexing assigned by NLM

MeSH

Anticoagulants /therapeutic use; Bandages; Hemorrhage /etiology; Heparin /therapeutic use; Humans; Postoperative Complications /prevention & control; Surgical Procedures, Operative /adverse effects; Thromboembolism /prevention & control; Wounds and Injuries /complications

AccessionNumber

12010003543

Database entry date

20/07/2011

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: 20020289

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