Program of venous thromboembolism prophylaxis: a model of continuing medical education
(Portuguese PDF version)

Jackson Silveira Caiafa1, Marcos de Bastos2

1. Head of the Division of Endovascular Surgery and Angioradiology of Hospital Municipal da Lagoa, Rio de Janeiro and former head of the Angiology and Vascular Clinic of Hospital Naval Marcílio Dias, RJ.
2. Department of Hematology of Hospital Geral Israel Pinheiro, Belo Horizonte.

Correspondence:
Dr. Jackson Silveira Caiafa
Av. Nossa Senhora de Copacabana, 400/202
CEP 22020-000 - Copacabana - RJ
Tel/Fax: +55 21 2549.7855
E-mail: intervasc@easyline.com.br

The study was partially financed by Rhodia Pharma/Aventis (sponsorship for data typing).

ABSTRACT

Objectives: To assess the use of a previously described method for the classification of venous thromboembolic risk factor; to develop appropriate software; to evaluate the current prophylactic practices in a large Brazilian general hospital and to assess changes of pattern in the clinical practice and their impact on outcomes.

Methods: The risk class was determined by the number of risk factors presented by each patient at admission, written in a specific form. This form also provided each entry with recommended prophylactic regimens according to the consensus guidelines. At discharge, symptomatic and objectively confirmed venous thromboembolism, heparin induced thrombocytopenia, bleeding and the type of prophylaxis actually given were recorded.

Results: From October 1995 to August 1999, 18,690 patients were evaluated. Risk factors were classified as moderate in 8,012 (42.87%) and high in 880 (4.7%). 52.9% of high-risk patients received inadequate regimens, 33% of moderate-risk patients received no prophylaxis and 6.5% of low-risk patients received inadequate heparin prophylaxis. The most frequently observed risk factors were age > 40 years, pregnancy, prolonged surgery time and obesity. Minor and major bleeding was observed in 14 (0.51%) and 11 cases (0.4%), respectively, with heparin prophylaxis. There were 83 venous thromboembolism episodes. The monthly hospital consumption of prophylactic low molecular weight heparin increased drastically.

Conclusions: This method seems adequate to increase awareness of venous thromboembolism in a hospital setting. There seems to be an association between the increase in low molecular weight heparin consumption, the use of this protocol and the decrease in symptomatic venous thromboembolism. This study was a pilot scheme for the Brazilian Venous Thromboembolism Registry.

Key words: low molecular weight heparin, deep vein thrombosis, pulmonary embolism, thromboembolism
Palavras-chave: heparina de baixo peso molecular, trombose de veia profunda, embolia pulmonar, tromboembolismo.

J Vasc Br 2002;1(2):103-12.

INTRODUCTION

Venous thromboembolism (VTE) comprises deep vein thrombosis (DVT) and also pulmonary embolism (PE), which is the most serious and immediate consequence of DVT. In the acute phase, VTE is associated with a high probability of severe and often fatal complications. Its chronic phase can lead to physical incapacitation and incur in exorbitant socioeconomic and personal costs, with the development of severe chronic venous insufficiency, resulting in the so-called postthrombotic or postphlebitic syndromes.1,2 VTE is also described as the major cause of preventable in-hospital mortality.3-14 Necropsy studies show a rate of VTE death between 10 and 20% in general hospitals, of which VTE is either the major or the secondary cause.4,7,8,10,13,14 Death usually occurs within the first hour and the diagnosis is not usually considered.3,9,15 In our country, the study conducted by Menna-Barreto involving 767 necropsies at Hospital de Clínicas de Porto Alegre, between 1985 and 1995, detected VTE in 3.9% of the cases, of which 83% had not been previously diagnosed or considered.16

Most cases of VTE seem to be associated with well-defined clinical risk situations,3,4,17-25 known as risk factors. The screening of this disease by means of imaging tests in asymptomatic patients does not seem to be a cost-effective approach;26-29 on top of that, its treatment is expensive, subject to complications and is not totally effective in resolving late-onset complications. Therefore, an effective prophylaxis is the best alternative.

The efficiency of this approach, with the use of different prophylactic methods, has already been demonstrated in several meta-analyses19,30 and reaffirmed in international consensuses.3,21,25,31 Recent publications, however, suggest that the adoption of prophylactic measures by general hospitals is still dissatisfactory despite the great number of studies and activities conducted in this area.10,17,32-34

The present study describes the attempt of the Angiology and Vascular Surgery Clinic of Hospital Naval Marcílio Dias (HNMD), in Rio de Janeiro, to implement a program of VTE prophylaxis, with the aim of assessing the frequency of several risk factors in the population of this hospital; identifying and quantifying VTE risk categories; registering and standardizing prophylactic schemes, stratifying them by risk; determining the failure rate and prevention complications by means of clinical diagnosis; and disseminating VTE prophylactic schemes among physicians and hospital workers.

PATIENTS AND METHODS

A form was created for the registry of specific data on all hospital admissions. This form was obligatory for all medical files of patients aged 12 years or older. Based on this form, a software program (database), with multiple interactive screens, was developed in order to facilitate the final data analysis of VTE prophylaxis. The initial screen shows the hospital form for data collection (Figure 1).

click hereFigure 1 -Screen for VTE prophylaxis control (form attached to all medical files).

disch. = discharged
hosp. = hospital
yrs. = years
contracep. = contraceptives
acute myoc. inf. = acute myocardial infarction
IBD = inflammatory bowel disease
CHF = congestive heart failure
prlng. confin. to bed = prolonged confinement to bed
preg. = pregnancy
gnrl. anest. = consideration for general anesthesia
w/ lrg. orthop. surg. = large orthopedic surgery
w/ prev. TE = with previous thromboembolism
w/ identified disorders of coag. facts. = with identified disorders of coagulation factors
w/ prostatec. / lrg. surg. for malign. diseases = with prostatectomy / large surgery for malignant disease
interm. pneum. comp. = intermettent pneumatic compression
bldng. = bleeding

Identification

With the aim of unequivocally identifying the patient, the form includes fields such as name, age, total cumulative admissions, sex and hospital clinical practice, in addition to data related to hospital admission, such as date of admission and date of discharge, length of stay and occurrence of death.

Risk factors

The objective of the form is to compile VTE risk factors, selected by the clinical committees of the hospital, according to previously published guidelines.20,23-25,35-38 Risk factors were categorized as follows: usual risk factors and high risk factors for VTE. Usual risk factors included age over 40 years; obesity; severe infection; thick varicose veins in lower extremities; use of estrogen at any dosage; pregnancy or puerperium; intestinal inflammatory disease; dyslipidemia; diabetes mellitus; immobilization of lower limbs (plastering, for example); neoplasia; consideration for general anesthesia; acute myocardial infarction or stroke in the last three months; past history of venous thromboembolism (longer than two years ago); prolonged confinement to bed (longer than three days); congestive heart failure; lower extremity trauma; fracture or polytrauma; surgery longer than 60 minutes; among others, if unrelated. High risk factors for VTE, regardless of the association with any other clinical situation, include large surgeries for neoplastic, prostatic or orthopedic diseases; presence of VTE in the last two years; recent rachimedullary trauma (last three months); and thrombophilia.

Classification (risk groups)

This subdivision includes the determination of VTE risk. This categorization was used by means of an algorithm developed for the system, through which the presence of any of the high risk factors automatically allocates the patient to the category of high risk for VTE. When only usual risk factors are present, they are added and, according to the number of identified risk factors, the risk category is determined. The presence of five factors or more implies the inclusion of the patient in the category of high risk for VTE. The presence of two to four risk factors designates moderate risk and none or one factor indicates low risk.

Used prophylaxis

Used to register the prophylactic scheme or its absence, as decided by the assistant physician. Such registry could also be made by a trained nurse. After hospital discharge, the vascular surgery clinic could also make this registry by referring to the medical files of the patient.

Result

Similarly to the previous subdivision, the result could be filled in by the assistant physician, nurse or by the vascular surgery clinic personnel. The diagnosis suspected by the assistant physician is registered and confirmed by objective exams for venous thrombosis and/or pulmonary embolism, developed during the hospital stay. The following exams were deemed adequate for the diagnosis: color echo-Doppler, venography, ventilation/perfusion lung scintigraphy and pulmonary arteriography.

Complications

Field used for the registry of possible complications caused by pharmacological prophylaxis or for the registry of the lack of such complications. The assistant physician was in charge of registering the diagnosis.

Therapeutics

Subdivision used for the identification of patients who, at hospital admission, were on anticoagulant therapy, and therefore were not subject to pharmacological prophylaxis for VTE. This subdivision allows the patients with out-of-hospital VTE to be excluded from the final analysis of the cases of venous thromboembolism developed during hospital stay.

System for data collection

The identification data, risk factors and classification of risk groups were obtained during the initial interview and also by the handling of the medical files at hospital admission by trained nurses. After data collection and the described analysis, the assistant physician included the recommended prophylaxis. No recommendation or prescription of any prophylactic scheme by the assistant physician was regarded as obligatory. The assistant physician only had to register his/her prophylactic option at admission, his/her impression about the existence of VTE, and the complications caused by pharmacological prophylaxis at hospital discharge. After hospital discharge, the form was removed from the medical files, checked and referred for inclusion in the database.

Prophylactic suggestions

The following standardized prophylactic suggestions were informed to all clinics and services of HNMD:

High-risk group - general care (early ambulation and/or active/passive movement, elevation of the feet, wearing of graduated elastic stockings); intermittent pneumatic compression; conventional heparin (5,000 IU SC every 8hrs), enoxaparin (40 mg/SC/day) or nadroparin (100 IU/kg SC/day up to 3rd day and 150 IU/kg SC/day after 3rd day).

Intermediate- or moderate-risk group - general care (early ambulation and/or active/passive movement, elevation of the feet, wearing of graduated elastic stockings); conventional heparin (5,000 IU SC every 12hrs), enoxaparin (20 mg/day) or nadroparin (7,500 IU SC/day).

Low-risk group - general care (early ambulation and/or active/passive movement, elevation of the feet, wearing of graduated elastic stockings); the use of any type of heparin or pharmacological prophylaxis is recommended.

The surgical prophylaxis for moderate risk should be implemented two hours before the surgery; and for high-risk patients, it should be initiated 12 hours before. For block anesthesia, pharmacological prophylaxis should be administered one hour after catheter insertion, and the catheter should be removed one hour before the next dose. In addition, it is advisable to maintain the prophylaxis for seven to 10 days, or while the risk persists.

Information provided to the clinical staff

Results: The presence or absence of venous thromboembolism and its location (DVT and/or PE) should be described. The diagnosis of DVT and PE should be done after clinical suspicion by the assistant physician and objectively confirmed by conventional imaging exams, such as color echo-Doppler, venography, ventilation/perfusion lung scintigraphy and pulmonary arteriography, coordinated by the vascular surgery and pneumology clinics.

Complications: The presence of minor or major bleeding, heparin-induced thrombocytopenia or absence of complications should be assessed. Major bleeding is characterized by the necessity of blood derivatives or decrease in serum hemoglobin level greater than 2 g/L. Heparin-induced thrombocytopenia (HIT) was defined as a decrease of 50% in the baseline value after drug therapy is initiated, or after the normalization of platelet count following heparin discontinuation.

Therapeutics: Used to identify the patients referred for anticoagulant therapy, either with conventional heparin or low molecular weight heparin (LMWH) or oral anticoagulants. This group should be identified in order to allow sorting out patients admitted to hospital with suspicion or diagnosis of VTE or on anticoagulant therapy due to other causes (for example, synthetic heart valves) and therefore not subject to VTE prophylaxis.

Statistical analysis

For statistical analysis, the chi-squared test, Student t test and Fisher's exact test were used, according to the guidelines presented in specialized texts.39

RESULTS

Identification

Between October 1995 and August 1999, 18,690 patients admitted to Hospital Naval Marcílio Dias, Rio de Janeiro, were assessed. These patients corresponded to 41% of hospital admissions during this period. The male/female ratio was 0.64 (approximately 2:3). The mean age of inpatients was 45 years. The four risk factors more frequently observed, in order of frequency, are shown in Table 1.

click hereTable 1 - Most frequent risk factors

Factor

n (%)

Age over 40 years

4,824 patients (25.8%)

Pregnancy

4,730 patients (25.3%)

Long-lasting surgery

3,000 patients (16.1%)

Obesity

1,082 patients (5.8%)

Classification of risks

9,798 patients (52.43%) were classified as low risk, 8,012 (42.87%) were considered to have moderate risk and 880 (4.7%) were classified as high-risk patients (Figure 2). The number of males at risk for VTE progressively increased: 35.4% in the low-risk cases, 42.6% in moderate risk and 48% in the high-risk group. This variation is highly significant ( x2 test, P<0.001).

click hereFigure 2 - Distribution of patients according to risk group.

Prophylactic schemes used

Among low-risk patients, 4.6% received some kind of pharmacological prophylaxis, which is in disagreement with the protocol. General care was individually recommended in 60.2% of all low-risk patients; 35.6% of the patients did not receive any kind of prophylaxis.

Among moderate-risk patients, 23% received pharmacological prophylaxis. In 43.9% of the patients, only general care was provided. In this group, 33% of the patients did not receive any kind of prophylaxis.

In high-risk patients, 26.2% did not receive any kind of prophylaxis, and 26.7% received only general care (total of 52.9% of the patients with inadequate prophylaxis). In this group, 45.7% of the patients received some kind of pharmacological prophylaxis, with or without associated general care.

The recommendation of general care can be concomitantly made with the use of intermittent pneumatic compression or any other substances applied in pharmacological prophylaxis.

These data can be observed in Table 2.

click hereTable 2 - Prophylaxis according to risk

Prophylaxis* Low
n = 9,798		 Moderate
n = 8,012		 High
n = 880		 Total
n = 18,690
None 3,495 (35.6%) 2,648 (33%) 231 (26.2%) 6,374 (34.1%)
General care** 5,939 (60.6%) 3,844 (47.9%) 314 (35.7%) 10,097 (54%)
UFH 136 (1.4%) 525 (6.5%) 106 (12%) 767 (4.1%)
LMWH 319 (3,2%) 1,323 (16.5%) 297 (33.7%) 1,939 (10.3%)

* Some patients received more than one type of prophylaxis, since it was possible to associate general care with intermittent penumatic compression and/or heparin
** Includes early walking, early hospital discharge, active and passive physical therapy and use of antithrombotic elastic stockings
UFH = unfractionated heparin
LMWH = low molecular weight heparin

Use of LMWH

Enoxaparin (89.3%) was the most widely used LMWH, at doses of 20 or 40 mg, although nadroparin (0.3 and 0.6 ml) has also been used (10.7%).

Figure 3 shows the drastic increase in the use of LMWH in the study period.

click hereFigure 3 - Average monthly consumption of LMWH syringes in prophylactic doses.

Adverse events

Eighty-three episodes of VTE (0.45% of hospital admissions) were observed. The patients with this complication were significantly older than the inpatients without VTE (61 years according to t test; P<0.0001). In these 83 cases, when we determined the risk group, we found 21 patients in the high-risk group (25.3% of VTE or 2.38% of the total number of high-risk patients), 51 patients in the moderate-risk group (61.44% of VTE or 0.64% of the total number of moderate-risk patients) and 11 patients in the low-risk group (13.25% of VTE or 0.11% of the total number of low-risk patients). With regard to anatomical location, 55 DVTs, 20 PEs and eight DVTs/PEs (62.2%, 24.09% and 9.63%, respectively) were observed.

The mortality among patients with venous thromboembolism was greater (20/83 and 378/18,607 according to x2; P<0.0001). In these patients, the most frequently observed risk factors were immobilization of lower limbs (18.8%), obesity (18.8%), thick varicose veins (23.5%) and prolonged confinement to bed (28.2%). As to the prophylaxis used, 28 patients (33.73%) did not receive any prophylactic scheme or received only general care, 28 patients (33.73%) received LMWH, and 27 patients (32.53%) received conventional heparin.

The frequency of symptomatic VTE diagnosed at hospital discharge showed a remarkable reduction between 1995 and 1999, decreasing from 12.13 episodes per 1,000 hospital admissions in 1995 to 2.13 per 1,000 hospital admissions in 1999. This reduction is highly significant (P<0.001 according to Fisher's exact test), and especially important in the periods between 1995-1996 and 1998-1999, when the highest reductions were noted (Figure 4).

click hereFigure 4 - Annual rate of symptomatic in-hospital venous thromboembolism at HNMD between 1995 and 1999.

Even though the aim of the study was not to assess the efficiency of prophylaxis or to compare the different forms of heparin, the rate of VTE was higher in the group that received conventional heparin than in the group treated with LMWH. Although this may indicate therapeutic superiority of LMWH over conventional heparin, new and more specific studies are required in order to confirm this hypothesis. The superiority of LMWH over conventional "minidose" heparin, in terms of reduction in hemorrhage risk and better prophylactic efficacy, has already been suggested in meta-analyses, in situations such as high-risk orthopedic surgeries with major traumas.21,22,40,41 In relation to general or abdominal surgery of moderate risk, this is still arguable.22,42,43

Fifteen episodes of major bleeding and 46 episodes of minor bleeding were detected (0.08 and 0.25% of the total population). Among those patients who received pharmacological prophylaxis (2,706 patients), 11 (0.4%) presented major bleeding and 14 (0.51%) revealed minor bleeding. The patients who suffered bleeding were usually older (52.9 years on average) and proportionally had a higher risk of death (seven deaths in 61 hemorrhagic episodes against 391 deaths in the other 18,629 patients without hemorrhage). As to VTE risk factors, the most common associations were obesity (10 cases, 16.4%), neoplasias (11 cases, 18%), consideration for general anesthesia (13 cases, 21.3%) and prolonged surgeries (24 cases, 39.3%). With regard to the risk groups, 10 (16.4%) were high-risk patients, 36 (59%) showed moderate risk and 15 (24.6%) had low risk. Paradoxically, the use of heparin was detected in only 41% of hemorrhagic cases.

Thrombocytopenia was observed in seven patients (0.04%), and was related to the administration of unfractionated heparin in two cases (0.07% of the patients with pharmacological prophylaxis or 0.26% of users of unfractionated heparin). Heparin-induced thrombocytopenia was not detected in patients treated with LMWH. The mean age of these patients was 50 years.

DISCUSSION

The methodology adopted in this study was similar to that developed by the Worcester17 group, which includes the systematic review of medical files by especially trained professionals. The quantification of cases of in-hospital venous thromboembolism made by clinical diagnosis does not have the power to determine the real prevalence of the disease verified herein, but can be used for comparative analyses over time or even with other series of similar methodology. Due to the great number of oligosymptomatic or asymptomatic cases, the establishment of the real prevalence of VTE requires more demanding protocols and more aggressive exams for all the patients involved, which is not feasible in studies with such sample size.

It is noteworthy that because of the concern with hospitalization costs in the last few years, hospital discharges occur earlier and earlier; consequently, many cases of thromboembolism occur at home after hospital discharge.22,44 Studies with patients submitted to orthopedic surgeries with high risk for VTE reveal that prophylaxis in these cases should continue up to approximately four weeks after surgery.22 In cases of general surgeries, up to 25% of the cases of thromboembolism can occur at home after hospital discharge.22,44 This may underestimate the prevalence of VTE in this type of study, in which assessment is not possible after hospital discharge.

On the other hand, this series is very accurate for the identification of symptomatic VTE, since it requires diagnostic confirmation of clinically suspected cases by means of recognizably efficient complementary exams. As far as the other objectives are concerned, the study allows precisely determining the frequency of several risk factors, registering the prophylactic schemes used and determining the number of complications caused by pharmacological prophylaxis. The study also permits assessing the impact on the use of prophylactic measures by medical professionals.

The occurrence of venous thromboembolism in this series is similar to that found by Huber,44 who quantified in-hospital VTE in a large retrospective study. In this study, the rate of symptomatic pulmonary embolism at hospital discharge was 3.1 per 1,000 patients among 28,953 inpatients, a sample size that is quite similar to ours. Of these occurrences, 1/5 was fatal (1/5 of all PEs). The risk also increased with age and was associated with the presence of neoplasia and with the type of surgery. In a similar study, conducted by the Worcester4 group, the incidence of DVT and PE in hospitalized patients was 0.48 and 0.23 per 1,000 patients, again a sample size that is quite similar to ours; the incidence of DVT was better, possibly due to the short-term length of hospital stay and also because of the objectively confirmed cases.

With regard to the distribution of risk categories, Anderson17 describes an extensive series of general hospitals in Massachusetts, United States. In this series, the percentage of patients with none or one risk factor (equivalent to low risk in this series) was 52%; 47% for those with two to four factors (moderate risk); and 1% for those with more than five factors (high risk). Except for the high risk group, the numbers are similar to the ones in this study. Moreover, a later study carried out by the same group, 32 using age > 40 years, prolonged hospital stay (> six days) and presence of any additional risk factor (at least three factors) as criteria for VTE high risk, detected 17% of high-risk patients. We believe our results should be considered, with slight variations, since they are confirmed, for the Brazilian National Registry,45 with low, moderate and high risk rates of 47%, 45% and 8%, respectively. It is noteworthy that in this Registry, with similar methodology and simultaneously carried out in three Brazilian hospitals, there were slight changes in the classification algorithm with the inclusion of a larger number of risk factors in relation to the pilot study.

Some recommendations for prophylaxis, especially American recommendations, subdivide the high-risk group in high risk (actual) and very high risk (or extremely high risk). The latter includes large surgeries, patients > 40 years, previous VTE, malignancy, orthopedic surgery of lower limbs or hip, trauma, stroke or rachimedullary trauma. The high-risk group (actual) includes large surgeries, age > 40 years, in addition to other risk factors or acute myocardial infarction. The difference, with some exceptions, would be the intermittent pneumatic compression associated with LMWH or conventional heparin in minidoses, which are normally used for the high-risk group in this classification. This classification, however, is not universally accepted and adds one more class to the risk group, thus hindering prophylactic schemes. In our opinion, this system is impractical, except for the case of hospitals with a great number of orthopedic surgeries, as in the study conducted by Heit.46

Another important aspect is the dosage of LMWH for high-risk clinical patients; there are medical data that indicate that in these cases the highest prophylactic dose should also be used.47 Our study had already adopted such recommendation by using the correct dosage for this kind of patient.

A positive aspect to be observed is that the program seems to encourage pharmacological prophylaxis, as shown by the increase in the use of LMWH. This increase can have some impact on the reduction of symptomatic venous thromboembolism detected at hospital discharge.

On the other hand, even with technically adequate prophylactic schemes, this is not always followed. For example, in the high-risk group, 52.9% of the patients did not receive prophylaxis or received inadequate prophylaxis, that is, they received only general care, when pharmacological prophylaxis is the accurate recommendation. In the case of the moderate-risk group, 1/3 of the cases did not receive any kind of prophylaxis. Therefore, a lot of work is required regarding medical education and the "dissemination" of prophylactic protocols, especially considering that this hospital has the tradition of encouraging VTE prophylaxis and has a specific ongoing program for over five years, when this study was implemented. Finally, nearly 5% of the low-risk cases received pharmacological prophylaxis with some form of heparin, contrary to what is recommended at hospital admission.

This inadequate medical conduct, despite the widespread dissemination of prophylactic recommendations in the last few decades, is not new. The verification of prophylactic standards in the United States suggests that only a small number of physicians use prophylaxis systematically and that it is more frequently used at university units.21,32 Recent studies suggest that programs with a greater interaction between sectors specialized in VTE and the clinical staff of the hospital, in addition to continued training and periodical statistical analyses, could improve this situation.21 The system described in this study meets or favors these three prerequisites.

With regard to adverse effects, the frequency of heparin-induced thrombocytopenia is low if compared to the literature.48 This may be due to the relative lack of active search for this complication; however, this fact is more likely related to the preferential profile of LMWH use, which induces this complication less frequently.

When we analyze the occurrence of hemorrhage, minor bleeding is detected in ¾ of the cases, and is more common in elderly patients, in patients who suffer from neoplasia, are obese, or in those patients submitted to prolonged anesthesia or general anesthesia. It is no surprise that death rates were more frequent in patients with hemorrhage, since this reveals a worse clinical status of the patient; curiously enough, however, only 41% of the cases of bleeding were associated with the use of heparin.

Bearing in mind the success achieved, the hospital form was updated and the software upgraded in order to include more recent recommendations regarding risk factors. In the second semester of 1999, a Brazilian National Registry for VTE prophylaxis was implemented under the coordination of the Brazilian Society of Angiology and Vascular Surgery. Initially, three large hospitals were included: Hospital Marcílio Dias (Rio de Janeiro), Hospital São Rafael (Salvador) and Hospital Austa (São José do Rio Preto). The results of this program have been recently presented at an international congress.45 Later on, another 11 hospitals from all over Brazil were included. Currently, the program is being improved, with the inclusion of many other centers. This will allow for an in-depth analysis of the Brazilian reality in this area or field.

CONCLUSIONS

The method used herein, with standardization of risk factors, categorization of risk groups, recommendation for VTE prophylaxis, adoption of a centralized data collection system, in addition to the analysis and regular publication of results, seems to be adequate to promote knowledge about the disease and about the classification of venous thromboembolism risk. Together with a program of continued education, this method can improve the application of prophylactic measures in the hospital environment. Nevertheless, a more comprehensive study should be carried out in order to improve these results, since more than half of the high-risk patients did not receive adequate prophylaxis, despite the recommendations.

There appears to be some association between the use of LMWH, this prophylactic scheme, and the reduced detection of symptomatic venous thromboembolism at hospital discharge.

Unfortunately, this type of study does not allow determining the prevalence of VTE in patients after hospital discharge. Some patients can suffer from late-onset VTE at home and due to early hospital discharge, they may be left out of this type of analysis, which would artificially reduce the frequency of symptomatic VTE in the study.

The project of HNMD was the starting point for the National Registry of Venous Thromboembolism by the Brazilian Society of Angiology and Vascular Surgery, currently in use at 14 institutions all over the country.

ACKNOWLEDGMENTS

We thank the board of directors of Hospital Naval Marcílio Dias for their support in the last eight years.

We also thank Drs. Eduardo Werneck, Eduardo Chaib, Egídio Joia, and Luís Carlos Moreira Rocha for their assistance and collaboration. Thanks to resident doctors and former resident doctors Marcus Gress, Ricardo Torrentes, Fernando Giordano, Carla Duarte, Marcio Fonseca, Cristiane Araújo and Clodoaldo Rayol of the Vascular Surgery Clinic of HNMD for their effort and dedication.

We would like to thank Tânia Boguchi for helping with the statistical analysis.

We thank Drs. Menna-Barreto, Liberato K. Moura and Selma Raimundo for their collaboration during the project development.

Special thanks to Ms. Silvia Pertile for typing 70% of the files in this registry and also thanks to the workers of the Center for Studies and library of HNMD.

This study was partially published as an abstract at the 18th Congress of the International Society of Thrombosis and Hemostasis (Paris).45,49

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