Venous Thrombosis Risks in Stroke

CHAPTER ONE

1.0 Introduction

Patients with acute stroke are at a high risk of developing various types of venous thrombosis such as pulmonary embolism and deep venous thrombosis (DVT) (Andre et al., 2007). Earlier studies (e.g. Andre et al., 2007, Dennis et al. 2009) indicate that in the absence of prophylaxis, DVT and pulmonary embolism occurs in 40% and 5% of patients with asymptomatic DVT respectively. There are various treatment interventions for DVT including low-molecular-weight heparin low-dose unfractionated heparin, that has been developed to address the health problem of DVT, but existing research also shows that these interventions may cause increased intracerebral hemorrhage among patients with ischemic stroke (Andre et al., 2007). Consequently, practitioners have resorted mechanical interventions for reducing venous stasis because they can work effectively without causing any bleeding risks (Naccarato et al. 2010). According to Naccarato et al. (2010), some of the currently existing mechanical interventions include intermittent pneumatic compression devices and graduated compression stockings (i.e., ankle levels or thigh level). Specifically, the graduated compression stockings apply pressure to reduce the pooling of blood in the deep veins, and are considered easier to use, less expensive and allow for easier mobility (Naccarato et al. 2010). With regards to existing evidence on their efficacy post-surgery (National Institute for Health and Clinical Excellence, NICE 2010) or in small bodies (Muir et al, 2000), graduated compression stockings are effective in patients with stroke, and are a preferable interventions applied by physicians for patients after stroke (Naccarato et al. 2010, Bergmann et al. 2010). However, their effectiveness has been challenged by another body of research, thereby creating a debate on their effectiveness and usefulness for patients with stroke. For instance, two randomized control trials (Dennis et al. 2009, The CLOTS, 2010), also termed as Clots in Legs Or Stockings after Stroke, CLOTS, challenged the use of graduated compression stockings as an intervention of DVT in stroke patients as well as its use in other patient populations. Mainly, CLOTS trials were a series of three randomized control trials that examined the effectiveness of graduated compression stockings for the prevention of DVT in patients with acute stroke. The first CLOT study, Dennis et al. (2009), involved 2500 patients in comparing graduated compression stockings and no graduated compression stockings. The results indicated that graduated compression stockings were ineffective in preventing asymptomatic DVT in patients with acute stroke. On the other hand, CLOTS 2 (The CLOTS, 2010) compared kneel level stockings with thigh level stockings among 3014 patients found that a few patients had cases of venous thromboembolism among patients in the thigh-level stocking group compared to the group with knee level stockings.

1.1 Statement of the Problem

Whereas scholars have successfully interpreted the results of CLOTS 1 and two separately, a challenge has majorly been encountered in the combined interpretation of the two studies. For instance, if Dennis et al. (2009) found that thigh-level stockings are ineffective, why did The CLOTS (2010) find that they are more effective than knee-level stockings? Nonetheless, the CLOTS researchers also raised an issue that stockings could increase the risk for venous thromboembolism. Interestingly though, other studies (NICE 2010, Sajid et al. 2006) have evaluated the effectiveness of knee-level stockings among long-distance travelers found that knee level stockings were effective than knee-level stockings. Other researchers have also interpreted CLOTS 1&2 results that thigh level stockings are 20% effective in reducing venous thromboembolism. This slight reduction found in CLOTS 1 could not have been evident and would be similar to the findings of the CLOTS 2 trial if knee level stockings did not affect venous thromboembolism. Hence, there is a controversy over the effectiveness of stockings in the treatment of DVT. The main aim of this study, therefore, is to explore other existing literature and establish whether stockings are effective interventions for DVT.

1.2 Research objective

To investigate the effectiveness of stockings as an intervention for DVT in patients with acute stroke

1.3 Research Question

Are stockings effective in treating DVT in patients with acute stroke?

1.4 Justification of the Study

While it is possible to speculate that the difference in findings of CLOTS 1&2 studies could be as a result of methodological differences, this may not be the case because despite being conducted in different clinical centers, the two studies used very similar types of patients. Furthermore, both CLOTS 1 and CLOTS 2 used thigh level stocking, applied the same follow-up procedure, had a similar definition of the primary outcome, and used the same tools to measure the primary outcomes. Therefore, based on these conflicting findings, the current study seeks to deliver some answers to practitioners on how to treat DVT in stroke patients, by primarily answering the question on whether stockings are effective interventions for DVT in stroke patients. The currently existing evidence (Dennis et al. 2009, The CLOTS, 2010) indicate that stockings are modestly capable of treating DVT in stroke patients. However, in the spirit of evidence-based practice, there is a need to establish, in high distinction, whether or not stockings are effective interventions for DVT in patients with stroke. Therefore, through a review of literature, the current study will draw evidence from a variety of studies (not only CLOTS 1&2) to have a clear understanding of the issue at hand. In doing so, the research shall have contributed additional knowledge on stockings as an intervention for DVT in stroke patients and provided an up to date comparison of evidence. Ultimately, the findings of this study could be used as a basis for future research, or for improving knowledge on DVT care among stroke patients.

CHAPTER TWO

2.0 Research Methodology

2.1 The Literature Review Method

A literature review is a research methodology that entails an identification, evaluation, and analysis of research evidence regarding a specific topic and field of study (Egger et al., 2001). It involves an acknowledgment of what is already known about the phenomenon under investigation – based on the researcher’s interest in the gaps of knowledge within that specific topic area. The current study is a literature review that seeks to identify and synthesize existing evidence on the effectiveness of stockings as an intervention for DVT in stroke patients. Therefore the study aims to identify, analyze, and interpret what is already known about stockings as an intervention of DVT in stroke patients. The literature review methodology is considered the most appropriate for this particular study because it creates an opportunity for the researcher to focus on what is already covered in the field of study, and to vary the usability of data based on the study objectives (Forbes & Griffiths, 2002). After providing an extensive background description of the topic under investigation, the literature review methodology will identify any existing new research evidence, the areas that are not significantly relevant to the current topic, and a suggestion for further research based on what is already known. Furthermore, according to (Glaszlou et al., 2001), a literature review methodology allows the researcher to be flexible in concentrating on different evidence that may be relevant and beneficial to the research objective. It enables the researcher to speak with self-knowledge, acknowledge shared knowledge, and develop a thoughtful practice based on existing evidence (Williamson et al., 2002). It is therefore clear that the application of this flexibility and the determination to gain confirmation from a diversity of scholarly materials will help in the development of a case for or against the use of stockings as an effective intervention for DVT.

2.2 The Review Process

The researcher adopted an elaborate and systematic approach in selecting literary materials for use in the literature review. The initial stages of the study selection entailed a search of the literary materials from relevant online databases, a process which yielded thousands of journal articles. The retrieved journal articles were then narrowed down to the most useful and relevant ones. Ultimately, a total of five articles were chosen for final review through the critical analysis process. Notably, the journal articles were retrieved from ProQuest, PUBMED and Google Scholar Using specific keywords such as deep vein thrombosis, venous thromboembolism, stroke, compression stockings, outcomes, prevention, and graduated compression stockings. During the search process, the keywords were combined using Boolean operators AND and OR, whereby OR was used to narrow down the search by combining similar words, while AND was used to expand the search by combining unrelated words. To ensure that the entire search process was trustworthy, the researcher only retrieved literary materials strictly from academic databases accessed through the student online portal. Furthermore, the researcher was only interested in articles that contained themes related to the topic under investigation. Mainly, the articles focused on the effectiveness of stockings as an intervention for DVT in stroke patients. They were focusing on either knee level or thigh level stockings and how they compared in terms of their effectiveness.

2.3 Data Collection

The database searchers were used for the final data collection. Each database was considered in the search process and yielded at least one relevant journal article. During the search process, the researcher used an inclusion/ exclusion criteria to limit the search and ensure the specificity of the reviewed evidence. For instance, the included studies were those published in the English language for purposes of comprehensive analysis, could be retrieved in full text, and relevant to the study topic. Therefore, the studies are written in any other language, not fully retrievable, and not related to the research topic were excluded from the review. It was deemed that the inclusion/exclusion criteria could fundamentally help in limiting the scope of the study to enable the achievement of specific results, hence, the easiest way to confine the study to compression stockings only. The table below illustrates the search outcome based on the inclusion/exclusion criteria:

The researcher identified thousands of journal articles, many of which were not included in the review because they failed to meet the including criteria. Besides, the researcher identified similar articles in certain instances of the search process. Hence, the inclusion criteria were essential in limiting the articles to the most relevant and most useful ones. Furthermore, because the study was targeted as a specific theme, most of the selected articles provided useful data in answering the research question. Meanwhile, the researcher began the study evaluation by reading the abstracts and study tittles to determine whether they meet the inclusion/exclusion criteria and if they contain information relevant to the research topic. Ultimately, a total of five articles were selected for final review. The studies were selected using specific search terms including deep vein thrombosis OR venous thromboembolism, outcomes OR prevention, outcomes, prevention OR graduated compression stockings. For further assurance that the reviewed evidence would be of good quality, the researcher conducted a critical appraisal of all the studies using a critical appraisal tool, namely: Critical Appraisal Skills Program (CASP). According to Egger et al. (2001), the CASP helps in evaluating the reliability and trustworthness of most types of studies using a checklist of at least ten questions. Each of the questions generally helps the researcher to gauge the study results, whether the results are credible, and whether the results are applicable in a local context (Forbes & Griffiths, 2002). Ultimately, the assessment procedure showed that all the included journal articles were of moderate to high-quality studies.

2.4 Data Extraction and Synthesis

The researcher developed a data extraction tool to assist in identifying and recording relevant information on the studies selected for final review. Notably, the information of interest was: the study title, authors, study findings, and its implications for practice. The extracted data were then synthesized using the grounded theory approach, which entails a systematic comparison of data to develop coherent conclusions (Williamson et al., 2002). Because each study had a distinct research methodology, the researcher used thematic analysis to separate and discuss the emerging themes.

CHAPTER THREE

3.0 Results

3.1 No Treatment Effect Evidence

The study search process yielded two randomized control trials, the first one being Muir et al. (2003). Muir et al. (2003) included non-independently ambulant patients who were unable to maintain a straight posture of their legs for five seconds. On the other hand, Muir et al. (2003) excluded patients with comatose, severe dermatological conditions and limb ischemia. The researchers randomized a total of 65 patients to stockings, while 32 other patients were randomized to a different type of care. For purposes of collecting baseline data, the researcher conducted an ultrasound on each patient to establish the presence of DVT. One ultrasound was performed before the application of stocking intervention; the second one was completed two days before or after an elapse of one week. The results showed no significant improvement in DVT as indicated by an odd ration of 0.43, and 95% confidence interval. However, there were several limitations to the findings of this study, including small sample size and the use of two distinct GCS. Furthermore, Muir et al. (2003) experienced a high drop-out rate especially during the second ultrasound, whereby 20 patients in the intervention group dropped out while six patients dropped out in the control group. Ultimately, Muir et al 2003 concluded that stockings have no significant treatment effects on DVT in stroke patients. The second reviewed study was the CLOTS trial 1 (Dennis et al., 2009). The researchers conducted a multicentre randomized control trial to evaluate the effectiveness of thigh level stockings as an intervention for DVT in people with acute stroke. The study enrolled 2518 participants who had been diagnosed with acute stroke within the past one week and assigned 1256 to thigh level stocking intervention while 1262 patients were assigned to normal stroke care without stockings. The primary outcome measure was asymptomatic or symptomatic DVT in femoral or popliteal veins within one month of randomization. The results indicated the occurrence in 10% of the stockings patient group and 10.5% of patients in the control group (i.e., normal stroke care). Hence, Dennis et al. (2009) found a 0.5% non-significant risk reduction in the primary outcome. Nonetheless, Dennis et al. (2009) also found a significant increase in blisters, skin ulcers, necrosis, and breaks among the stockings group. Ultimately, Dennis et al. (2009) concluded that stockings should not be used as the treatment for DVT in stroke patients.

The next reviewed study was a Cochrane review by Mazzone et al. (2004) on the use of stockings as an intervention for DVT in stroke patients. Mazzone et al. (2004) were interested in evaluating the physical interventions for DVT in stroke patients and included two studies, namely Muir et al. and another study consisting of 26 patients. Ultimately, Mazzone et al. (2004) found that compression stockings had no significant effects on DVT, and therefore with the lack of evidence, the researchers concluded that stockings should not be used as a treatment intervention for DVT in stroke patients . In another study by Khan et al. (2014), patients were drawn from 24 US and Canada care centers for a randomized and placebo-controlled study after having and ultrasound-confirmed DVT within the last 14 days. A majority of the excluded patients received a standard anticoagulation therapy as a treatment for their DVT consisting of warfarin and heparin. Besides, the researchers excluded any patient who had arterial claudication thrombolytics, those who had a less than six months life expectancy, those who were unable to wear stockings due to physical disabilities and those who could not show up for follow-up visits. The participants were randomly assigned to wear elastic compression stockings or identical-looking elastic compression stockings for two years. Besides, the researchers blinded all the statisticians, care providers, and the study personnel, and asked the patients to wear the stockings on the affected leg each day immediately after waking up and before going to sleep.

Participant follow-up was conducted 6 12, 18 and 24 months post-intervention and the primary outcome was measured based on Ginsberg's criteria of ipsilateral pain and swelling for at least 30 days (Ginsberg et al., 2001) or the incidence of diagnosed post-thrombotic syndrome (PTS) 6 months post-intervention. Conversely, the researchers’ measurements of secondary outcomes were based on leg ulcers presence, the severity of PTS, adverse events, quality of life (QOL), and death. Mainly, PTS was measured using the Villalta scale, while QOL was measured using the Venous Insufficiency Epidemiological an Economic Study Quality of Life questionnaire (Villalta et al. 1994, Khan et al., 2006). The elastic compression stocking group contained 409 patients, while the placebo group comprised of 394 patients. The researchers collected similar baseline characteristics, including body mass index as well as anticoagulation treatment regiments among the two groups. With regards to dropping out rates, at least 95% of participants were wearing stockings one month after the launch of the investigation across the two treatment groups while at least 70% of the participants across the two groups were still wearing stockings one year after the start of the study. Ultimately, Khan et al. (2014) found no differences in the secondary outcomes. Furthermore, subgroup analysis indicated that the participant’s age and DVT severity did not affect the findings. Nonetheless, the researchers only found marginal benefits of elastic compression stockings on women participants compared to men, with a significance level of (P=.047). However, this p-value does not reflect the true difference because the confidence intervals (95%) behind the hazard ratios (1.13) for both genders had overlapped the null values. Ultimately, Khan et al. concluded that elastic compression stockings had no benefit as an intervention for DVT in stroke patients.

3.2 Positive Treatment Effect Evidence

In 1997, Brandjes et al. conducted a randomized control trial to assess the effects of compression stockings as a preventive measure for DVT, with primary outcome measurements being the rate of post-thrombotic syndrome. The study included two treatment groups. The first group (control group) was randomly assigned to no stockings for at least two years, after which the researchers measured the post-thrombotic syndrome using as a standard scoring system comprising of both objective and clinical measurement elements. Patient assessment was conducted quarterly during the first two years, and after every six months within five years. Mainly, after including 315 patients, excluding 44 and 77 failing to issue participation consent, the researchers randomly assigned 96 patients to compression stockings while 98 of them were assigned to not stockings. The results indicated that 20% of the participants in the stocking group had a post-thrombotic syndrome score of ⩾3 + 1 clinical sign compared to 47% of patients in the control group ( p<0·001). Furthermore, the researchers found 11% of patients in the stocking group developed severe post-thrombotic syndrome compared to 23% of patients in the control group. After a comprehensive evaluation of the results, the researchers found that 60% of patients within the first episodes of DVT could develop post-thrombotic syndrome, and compression stockings could help reduce these incidences by 50%.

3.3 Consensus Guidelines

In addition to the reviewed studies, the researcher also reviewed consensus guidelines for the treatment of DVT in stroke patients using compression stockings. The reviewed treatment guidelines included that for the United Kingdom, the USA, Australia and New Zealand, The European Union, and Italy. The following table illustrates the treatment guidelines regarding compression stockings in each country:

CHAPTER FOUR

4.0 Discussion and Conclusion

4.1 Incidence of DVT

Before the publication of Dennis et al. (2009), there was a lack of data on the specific use of compression stockings as an intervention for DVT among stroke patients. Dennis et al. (2009), however, provide strong evidence that the use of compression stockings does not significantly reduce the risk of DVT, but rather, it substantially reduces the risk of adverse occurrences such as critical limb ischemia and skin problems. But, it is essential to note that stroke patients are at a higher risk of skin illness due to their sensory changes and immobility (Xu, 2010). Although this review is focused explicitly on compression stockings as an intervention for DVT in stroke patients, data identified during the review indicates a real uncertainty about the true magnitude of DVT after stroke. However, data from an extensive review of other literature demonstrates that according to the first systematic review on the incidence of DVT, 53% of DVT occurs within the first ten days after stroke (Warlow et al. 1976a, Warlow et al. 1976b). While Warlow et al. (1976a) and Warlow et al. (1976b) used different methods to ascertain the incidence of DVT, it is clear that the DVT detection method is not the main factor contributing to the uncertainty about its incidence. The uncertainty about DVT incidence is also compounding the attempts by medical practitioners to ascertain whether various interventions such as early mobilization, rehydration or aspirin may also be effective in reducing DVT as was earlier speculated by Muir et al. (2000). Therefore, the current study argues that the problematic nature f DVT together with the failure of early heparin intervention indicate the critical need to establish the effectiveness or non-effectiveness of compression stockings as an intervention for DVT in stroke patients.

One of the reviewed studies (Muir et al. 2003) confirms that whereas DVT is a common occurrence in patients who are immobile due to acute stroke, DVT manifests itself in rare clinical forms. Furthermore, two randomized controlled trial studies reviewed in the current study indicate that compression stockings are associated with no significant effects on DVT, one of them (Dennis et al. 2009) indicating that compression stockings are associated with skin complications. Furthermore, most of the reviewed treatment guidelines showed that compression stockings should only be used when the patients report contraindications to anticoagulant treatment.

4.2 Minor Complications

However, the uncertainty over the effectiveness of compression stockings is still eminent. Considering the study populations of the reviewed randomized control trials, accurate estimation of the efficacy and effectiveness of compression stockings as an intervention for DVT will require a relatively larger population sample. While there were no serious complications reported in the reviewed studies, the minor complications (i.e., skin complications reported by Dennis et al. 2009) cause specific inconvenience to the patients and should not be ignored, and therefore compression stockings should only be used based on established clinical benefits. The risk of ineffective treatment, inconvenience, and discomfort associated with compression stockings led to a halt of participant recruitment in another study (CLOTS 2).

4.3 Effectiveness in Surgery

Interestingly, one of the reviewed studies (Dennis et al. 2009) showed that compression stockings had some effects on patients undergoing surgery, thus raising the question about what could have been the cause of this difference. However, an in-depth review of Dennis et al. (2009) indicates that the methodology and precision with which they applied it show unlikeliness that they had missed any clinical treatment effect. Besides, other studies on surgery patients have shown convincing evidence that compression stockings are effective in preventing DVT among surgery patients when applied after, before and during an insult of deep leg veins (Roderick et al., 2005). Roderick et al. (2005), in their systematic literature review, reported that only 8 of the 17 reviewed studies indicated a frequent occurrence of proximal DVT (only 5% of the patients allocated to compression stockings reported the incidence of proximal DVT).

4.4 Immobile Patients

Nonetheless, the reviewed literature indicates that in the case of stroke patients, compression stockings can be applied after the patients have become immobile, and the immobility may persist for a while or occur permanently in some patients. Therefore, the development of DVT is typically rapid and can, therefore, not be controlled effectively through any treatments that start immediately after immobility. The review also indicated an impossibility of testing the effectiveness of compression stockings before the onset of stroke. Compression stockings are said to reduce DVT based on various mechanisms. For instance, it produces a pressure gradient in the leg that increases the velocity of the blood. Besides, it reduces the cross-sectional area of the deep veins, thereby increasing the effectiveness of the calf muscle pump. However, considering that the calf muscle pump does not work effectively in patients with weak legs, the latter mechanism may not work effectively in stroke patients with thin legs meaning that compression stockings may not be effective in this group of patients (Dennis et al. 2009). It is possible to argue that stroke patients with stronger legs may be akin to immobile medical patients compared to surgery patients. Hence, the ineffectiveness of compression stockings even in the presence of some leg movements, as revealed by the current review, indicates that compression stockings can be useful in acute medical patients. However, this assumption needs further research to ascertain.

4.5 Proper size of fit

We also speculate that any incorrect usage or poor compliance with compression stockings may reduce its effectiveness. For instance, the manufactures of compression stockings featured in some of the reviewed studies (e.g., Dennis et al. 2009) emphasized that it is essential to identify the proper size and fit of the stocking. The size of the stocking depends on thigh and calf circumference as well as the patient’s leg length. An overview of the literature reveals that the compression stockings exist in 18 different thigh-length specifications and ten different thigh width sizes. Hence, based on the apparent complexity of achieving the best fit for each patient, it is highly likely that patients may be using the wrong fit specifications – and this may be detrimental to the compression stockings’ effectiveness. Researchers conducting trials on its effectiveness might have made similar mistakes. For instance, we speculate that the studies whose compliance rates were reasonable in the initial stages of the study but turned out to be poor were characterized by participants who became uncomfortable with the stockings over time, or the nurses might have been concerned about the stockings’ effect on the participants’ skins (e.g., Dennis et al., 2009). Nonetheless, we argue that the level of compliance in the reviewed trials was sufficient to warrant substantial conclusions about the study findings.

4.6 Conclusion

This study has identified mixed results on the effectiveness of compression stockings as an intervention to DVT in stroke patients. While some evidence favors the use of stockings for DVT prevention in stroke patients, the effectiveness relies widely on various factors within the clinical care setting. More importantly, there needs to be further research with larger sample populations to confirm the effectiveness accurately. New research on the effect size of compression stockings on DVT may help enhance evidence-based practice and comparison with other interventions in acute stroke care. Similarly, there is a need for further research on the relevance of stocking design and size on the treatment outcomes. Last but not least, a possible practice implication of this review is that whereas some practitioners may prefer to use compression stockings in DVT patients, they need to be keen on the sizing of the stockings by selecting the most accurate size for better treatment outcomes. Moreover, practitioners need to enlighten family caregivers on how to use stockings.

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