Meta Analysis
Venous Thromboembolism and Its Prevention in Critical Care
This review may be edited
Posted By: A Delaney
Posted Date: 8/8/2002
Title: Venous Thromboembolism and Its Prevention in Critical Care
Authors: William Geerts, Deborah Cook, Rita Selby, and Edward Etchells
Reference: Journal of Critical Care, Vol 17, No 2 (June), 2002: pp 95-104
Link: Click here for a direct link to the paper. A password may be required for access to fulltext.
Abstract: Background: Evidence-based guidelines for the prevention of venous thromboembolism (VTE) are available for most major surgical and medical patient groups. Such guidelines have not been established for critically ill patients. Objective: To perform a systematic review of the prevalence of deep vein thrombosis (DVT), the efficacy of thromboprophylaxis, and the rates of thromboprophylaxis use in critically ill patients. Methods: Computerized literature search for relevant studies meeting prespecified criteria. Results: The rates of objectively confirmed DVT in 4 prospective studies ranged from 13% to 31%. We identified only 3 randomized trials (1 in abstract form) of thromboprophylaxis in critical care unit patients. These studies show the efficacy of low-dose heparin and low molecular weight heparin compared with no prophylaxis; however, we found no trials comparing these 2 interventions. Eleven compliance studies reported that some form of thromboprophylaxis was used in 33% to 100% of critically ill patients, although only 1 study addressed the issue of appropriate prophylaxis use. Conclusions: Data on the epidemiology of VTE and its prevention in critically ill patients are very limited. Further research is needed to better define patient risk factors for VTE, optimal methods of thromboprophylaxis, and strategies to improve compliance with prophylaxis recommendations. In the meantime, prevention strategies, shown to be effective in other related patient groups, and general principles of individual pharmacotherapy should guide the routine use of prophylaxis during critical illness.
Are the Results Valid?
1. Did the overview address a focused clinical question?
The article reviews the literature describing the prevalence and prevention of thromboembolic complications as well as compliance with thromboprophylaxis in critically ill patients.
2. Were the criteria used to select articles for inclusion appropriate?
The criteria are probably appropriate to answer the questions about prevalence and prevention. The criteria used to select articles about compliance are not detailed.
3. Is it unlikely that important, relevant studies were missed?
The literature search included appropriate search terms, both Medline and Embase, and was from 1966 to January 2002. Bibliographies of retrieved articles were searched as were the authors personal files. The search was limited to English, other prominent authors in the field and representatives of industry were not contacted. Overall it would be unikely that important relevant studies were missed.
4. Was the validity of the included studies appraised?
The methodologic quality of the studies was assessed according to study design, consecutive patient enrollment, blinding of interventions and outcome assessment and completeness of follow-up.
5. Were assessments of studies reproducible?
The computer search,study selection and examination of articles was performed indepently by 2 authors. Three authors indepently extracted data from each study and disagreement was resolved by consensus.
6. Were the results similar from study to study?
Due to the variable nature of the studies included, it is hard to compare the results from the various studies.
What are the Results?
1. What are the overall results of the overview?
Prevalence: Autopsy proven Pulmonary Embolus (PE) was detected in 7% to 27% (mean 13%) of ICU patients and caused or contributed to death in 0% to 12% (mean 3%). Deep venous thrombosis (DVT) was found in 13% to 31%. Thromboprophylaxis: The use of low dose heparin (5000 units sci bd) reduced the rate of DVT from 29% to 13% compared to placebo in one study and from 31% to 11% in another. A similar reduction was found when a low molecular weight heparin (nadroparin) was compared to placebo from 28% to 15%. Compliance with thromboprophylaxis: The authors state that since 1994 compliance with thromboprophylaxis use has increased substantially, although only 2 of 34 Canadians units surveyed in one study used pre-printed orders and a practice guideline.
2. How precise were the results?
As the studies were varied in methodology, no estimate as to the precision of the results is possible.
Will the Results Help Me In Caring For My Patients?
1. Can the results be applied to my patient care
Venous thromboembolism is a common problem in the critically ill, and can result in important patient focussed outcomes (ie death). There is nothing apparent from the results presented to indicate that the results would not be generalizable to a general medical/surgical Intensive Care population. The results may not be extrapolatable to other Intensive Care populations such as Neurosurgery.
2. Were all clinically important outcomes considered?
There is very little data presented regarding the risk of bleeding with the various regimes presented. There is no data presented about costs. The other information which would be pertinent would be regarding the relative efficacy of mechanical means of thromboprophylaxis in a general Intensive Care population. The authors report that their search revealed no studies to formally evaluate these in this population.
3. Are the benefits worth the harms and costs?
The high incidence of venous thromboembolic disease in the critically ill and it's consequences mean that prevention is important. The means to lower this risk is available and is effective in lowering the rate of DVT in the critically ill. There is not a lot of specific data to determine the actual harms and costs so a definitive statment on this is difficult. As the authors point out, more research is needed to specifically answer questions such as this.
An evidence-based recommendation, which is the building block for an evidence-based guideline, that summarizes this topic can be found in the EBR section.

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