CRD summary

This review assessed the effects of anticoagulant prophylaxis in hospitalised medical patients. The authors concluded that anticoagulant prophylaxis is effective in preventing symptomatic venous thromboembolism during anticoagulant prophylaxis in at-risk hospitalised patients. This was a well-conducted review and the authors' conclusions are likely to be reliable.

Authors' objectives

To determine the effects of anticoagulant prophylaxis in reducing clinically important outcomes in hospitalised medical patients.

Searching

The authors searched MEDLINE and EMBASE from inception to September 2006 and the Cochrane Controlled Trials Register (Issue 3, 2006); the search terms were reported. In addition, reference lists were checked and content experts were contacted. The search was not restricted by language or publication status.

Study selection

Assessment of study quality

Two reviewers, who were blind to study authors and the journals in which the studies were published, independently assessed study quality. Methods of randomisation, double-blinding, and the description of patient withdrawals and drop-outs were assessed.

Data extraction

Two reviewers, who were blind to study authors and the journal in which the studies were published, independently extracted the data. Any disagreements were resolved by consensus or through discussion with a third reviewer. Data were extracted on the occurrence of each efficacy and safety outcome during the on-treatment prophylaxis period and during the entire on-treatment and after-treatment periods combined. Study authors were contacted for missing outcome data

Methods of synthesis

Results of the review

Nine RCTs (n=19,958) were included in the review.

In terms of study quality, randomisation was adequate in 9 studies, 7 studies were reported as double-blind, 5 studies provided a description of patient withdrawals, and 7 studies had concealed treatment allocation.

Based on 9 studies, anticoagulant prophylaxis resulted in a statistically significant reduction in the risk of any PE: the RR was 0.43 (95% CI: 0.26, 0.71), the absolute risk reduction was 0.29%, and the NNT to prevent one symptomatic PE was 345. Based on 7 studies, anticoagulant prophylaxis resulted in a statistically significant reduction in the risk of fatal PE: the RR was 0.38 (95% CI: 0.21, 0.69), the absolute risk reduction was 0.25%, and the NNT to prevent one death due to PE was 400.

Anticoagulant prophylaxis had no statistically significant effect on symptomatic DVT (RR 0.47, 95% CI: 0.22, 1.00), all-cause mortality (RR 0.97, 95% CI: 0.79, 1.19), or major bleeding (RR 1.32, 95% CI: 0.73, 2.37). Except for major bleeding, no heterogeneity across studies was found (I-squared 0%).

Sensitivity analyses did not change the results of the primary analyses. The funnel plot for any PE was asymmetrical, suggesting a lack of small studies showing an association between prophylaxis and an increased risk of PE and all-cause mortality. The funnel plot for major bleeding did not suggest the presence of publication bias. There were insufficient studies to produce funnel plots for the other outcomes.

Cost information

No

Authors' conclusions

Anticoagulant prophylaxis is effective in preventing symptomatic venous thromboembolism during anticoagulant prophylaxis in at-risk hospitalised medical patients. Further research is required to assess the risk for venous thromboembolism in these patients after prophylaxis has been stopped.

CRD commentary

The authors set out a clear objective and defined clear inclusion criteria for the participants, interventions, outcomes and study design. Appropriate sources were searched without any restrictions on language or publication status, which will have reduced the risk of publication bias and missing relevant studies. However, an assessment of publication bias revealed some evidence of publication bias for one outcome. Measures were taken to reduce the risk of bias and error in the study selection, data extraction and quality assessment processes. Study quality was assessed using appropriate criteria, and adequate study details were provided. The methods used to statistically pool the studies seemed appropriate, and statistical heterogeneity was assessed. This was a well-conducted review and the authors' conclusions are likely to be reliable. In addition, the authors appropriately stated that they were unable to determine the relative efficacy of different types of anticoagulants.

Implications of the review for practice and research

Practice: The authors advise caution in applying the findings of this study to practice and stated that clinicians should consider anticoagulant prophylaxis within the context of absolute therapeutic benefits, potential harms and costs, as well as the potential limitations of these findings. They further stated that the use of prophylactic anticoagulation should be selective and perhaps limited to high-risk patients.

Research: The authors stated that further research is needed to determine who should receive anticoagulant prophylaxis and for what duration, and to assess the risk for venous thromboembolism in at-risk hospitalised patients after prophylaxis has been stopped.

Bibliographic details

Dentali F, Douketis J D, Gianni M, Lim W, Crowther M A. Meta-analysis: anticoagulant prophylaxis to prevent symptomatic venous thromboembolism in hospitalized medical patients. Annals of Internal Medicine 2007; 146(4): 278-288. [PubMed: 17310052]

Original Paper URL

http://www.annals.org/cgi/content/full/146/4/278

Indexing Status

Subject indexing assigned by NLM

MeSH

Anticoagulants /adverse effects /therapeutic use; Bias (Epidemiology); Hemorrhage /chemically induced; Heparin /adverse effects /therapeutic use; Heparin, Low-Molecular-Weight /adverse effects /therapeutic use; Hospital Mortality; Hospitalization; Humans; Pulmonary Embolism /prevention & control; Sensitivity and Specificity; Thromboembolism /prevention & control; Venous Thrombosis /prevention & control

AccessionNumber

12007008071

Database entry date

31/07/2007

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.