Evaluation of prophylaxis for deep venous thrombosis in a General Hospital *
(Portuguese PDF version)

Carolina Marchi,¹ Isabela Braga Schlup¹, Carlos Augusto de Lima², Heraldo Alves Schlup³

1. Medical student, Universidade do Vale do Itajaí (UNIVALI), Itajaí, SC, Brazil.
2. Professor, Angiology and Vascular Surgery, UNIVALI, Itajaí, SC, Brazil.
3. Angiologist and vascular surgeon, Blumenau, SC, Brazil.

Correspondence:
Heraldo Alves Schlup
Armando Odebrecht, 70
CEP 89020-403 - Blumenau, SC, Brazil
Phone: +55 47 322.4663
Fax: +55 47 326.4542
E-mail: hschlup@terra.com.br

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ABSTRACT

Objective: Deep venous thrombosis is a multidisciplinary disease, which can be clinically and surgically present as a complication of hospitalization. The aim of this study is to verify whether the prophylaxis for deep venous thrombosis is being used at the Hospital e Maternidade Marieta Konder Bornhausen (HMMKB), in Itajaí (SC, Brazil), and whether it is being used adequately.

Method: A transversal, analytical, and descriptive study was performed at the HMMKB for a 30-day period. The sample was composed of 983 patients within different specialties. Patients were divided into clinical (63.7%) and surgical (36.3%). Clinical and surgical factors, as well as medications were surveyed for all patients. Based on these data, risk stratification and the evaluation of prophylaxis were established according to the classification suggested by the International Consensus Statement. Data were tabled and statistically analyzed, with the support of the software Epi-Info 2002.

Results: Of the 983 patients surveyed, 362 (36.8%) presented low risk for the development of deep venous thrombosis, 104 (10.6%) were considered medium risk, and most patients, 517 (52.6%), presented high risk. Of the 124 (12.6%) patients who received prophylaxis for deep venous thrombosis, only 46 (37.1%) received it adequately, and 859 (87.4%) did not receive any kind of prophylactic measure.

Conclusions: Despite the efficiency of the prophylaxis for deep venous thrombosis having been proven by several studies, it does not reach satisfactory levels in our environment.

Key-words: thromboembolism, venous thrombosis, prevention.

J Vasc Br 2005;4(2):171-5

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Deep venous thrombosis (DVT) is a disease that affects one or two people in every 1,000 inhabitants annually.¹

DVT, which is a multidisciplinary disease, is present as a complication of hospitalization in practically all clinical or surgical specialties. Cares concerning its prophylaxis, early diagnosis, and adequate and immediate treatment must always be considered in the daily routine of every physician, regardless of the specialty.²

The prophylaxis for DVT is of major importance, since it is the main cause of pulmonary embolism,³ which, in its turn, can be the first clinical manifestation of DVT and is usually lethal in 0.2% of hospitalized patients.⁴

The silent nature of DVT and its complications is revealed by the statistics, in which it can be seen that from 70% to 80% of pulmonary embolisms diagnosed post mortem have no previous clinical suspicions. Such characteristic presents enough reason to establish its prophylaxis.^2,5

Several consensuses have originated a rational prophylaxis for DVT. Concepts and treatments have been reviewed, making it possible to establish, within a reasonable safety margin, the thromboembolic profile of a patient based on risk factors.²

In spite of that, the routine use of prophylaxis is not regularly practiced in risk cases, both in developed countries ⁶ and in our environment.^7,8

The aim of this study is to verify whether the prophylaxis for DVT is being used in the Hospital e Maternidade Marieta Konder Bornhausen (HMMKB), in Itajaí (SC, Brazil), and whether it is being used adequately.

PATIENTS AND METHODS

A transversal, analytical, and descriptive study was performed at the HMMKB in October 2003, aiming at evaluating prophylaxis for DVT.

The study used a convenience sample of 983 patients hospitalized at the HMMKB, for a 30-day period, in the following departments: medical clinic, urology, general surgery, vascular surgery, orthopedics, and gynecology.

Data were collected through analysis of patients' medical charts, searching for clinical, drug, and surgical factors. All patients submitted to any type of surgical procedure during hospitalization were considered surgical.

Patients were divided into risk groups according to the International Consensus Statement, published by J Vasc Br in September 2002, regarding the prevention of thromboembolism, and were classified as low, medium, and high risk (Tables 1 and 2).⁴ The evaluation of the prophylaxis follows the recommendations of the International Consensus Statement, since it is supported by the International Union of Angiology, as well as by the Brazilian Society of Angiology and Vascular Surgery.

Table 1 - Risk categories for the thromboembolic disease in surgical patients

Risk	Characteristic of the surgery
Low	Surgeries in patients < 40 years old, with no other risk factor. Minor surgeries (< 30 min with no need of a prolonged rest) in patients > 40 years old, with no other risk besides age.
Medium	Minor surgery (general, urologic or gynecologic) in patients from 40 to 60 years old with no additional risk factors. Surgery in patients < 40 years old taking estrogen.
High	General surgery in patients > 60 years old. General surgery in patients from 40 to 60 years old with additional risk factors. Minor surgery in patients with history of deep venous thrombosis or previous pulmonary embolism or thrombophilia. Major amputations. Major orthopedic surgeries. Major surgeries in patients with malignant neoplasia. Major surgeries in patients with other hypercoagulability states. Multiple traumas with fracture of the pelvis, hip or lower limbs.

Adapted from Nicolaides et al.⁴

Table 2 - Risk categories for the thromboembolic disease in clinical patients

Risk	Characteristics of the patient
Low	Any disease.
Medium	Patients > 65 years old, affected by clinical diseases with no other risk others.
High	Any disease associated to deep venous thrombosis or previous pulmonary embolism. Any disease associated to thrombophilia. Myocardial infarction. Diseases associated to other risk factors for deep venous thrombosis. Cerebral vascular accident. Lesion in the spinal cord. Patients at the intensive care unit.

Adapted from Nicolaides et al.⁴

Since the research involved human patients, some ethical procedures had to be respected, such as:

• permission requirement to the ethics committee of the HMMKB;
  
• permission from each Head of Service;
  
• guarantee of secrecy, assuring the privacy concerning people and surveyed data;
  
• the patients, relatives, or legal representatives were not financially charged.

Data were tabled with the support of the software Epi-Info 2002. Absolute and relative percentages were presented in tables. Data were statistically analyzed, considering valid all data with P < 0.05.

This study is in accordance to the resolution 196/96 of the Brazilian Health Council, and it was approved by the Research Ethics Committee of the Universidade do Vale do Itajaí (UNIVALI).

RESULTS

Of the 983 patients surveyed, 362 (36.8%) presented low risk for the development of DVT, 104 (10.6%) were considered medium risk, and most patients, 517 (52.6%), presented high risk. Of all these patients, 859 (87.4%) did not receive prophylaxis for DVT. Among patients who received prophylaxis, only in 46 cases (37.1%) it was adequately applied.

Most patients were clinical (626 patients - 63.7%), and only 103 (16.5%) clinical patients and 21 (5.9%) surgical patients received prophylaxis for DVT.

Of the 621 patients indicated to receive chemoprophylaxis (medium and high risk), only 127 (20.45%) received it. Of these, 107 (20.7%) were high risk and 10 (9.6%) were medium risk. Prophylaxis for medium-risk patients was adequate in 70% of cases (seven patients). Patients presenting high risk for developing DVT received adequate prophylaxis in only 34.6% (37 patients) of cases.

Of all specialties that were surveyed, gynecology and obstetrics used prophylaxis in only one patient (0.40%). Medical clinic was the specialty that most used prophylaxis, applying it in 21.60% of cases.

Of the 12 general surgery patients who received prophylaxis for DVT, 50% (six patients) received it adequately, while in other specialties the index of prophylaxis was lower.

Table 3 shows the frequency of patients, prophylaxis, and appropriateness of prophylaxis, according to the surveyed specialties, as well as the frequency and appropriateness of prophylaxis according to risk groups.

Table 3 - Frequency of patients, prophylaxis, and appropriateness of prophylaxis by specialty, as well as frequency and appropriateness of prophylaxis according to risk groups

	With prophylaxis	Without prophylaxis	Appropriate prophylaxis	Inappropriate prophylaxis
Specialty (n -%)	n (%)	n (%)	n (%)	n (%)
General surgery 124 - 12.6	12 (9.7)	112 (90.3)	6 (50)	6 (50)
Medical clinic 408 - 41.5	88 (21.6)	320 (78.4)	31 (35.2)	57 (64.8)
Vascular surgery 64 - 6.5	9 (4.1)	55 (85.9)	2 (22.2)	7 (77.8)
Gynecology 241 - 24.5	1 (0.4)	240 (99.6)	1 (100)	0 (0)
Orthopedics 102 - 10.4	9 (8.8)	93 (91.2)	4 (44.4)	5 (55.6)
Urology 44 - 4.5	5 (11.4)	39 (88.6)	2 (40)	3 (60)
Risk	n	n	n	n
Low (n = 362)	7	355	2	5
Medium (n = 104)	10	94	7	3
High (n = 517)	107	410	17	90

P < 0.05

 

DISCUSSION

The prophylaxis for DVT is necessary and essential in the prevention of complications, such as the pulmonary embolism, and sequels, such as the post-thrombotic syndrome. Particularly due to the silent nature of DVT, pulmonary embolism (PE) is often its first manifestation.⁹ That is the reason why prophylactic measurements are indicated and discussed by several authors, aiming at developing protocols every time more detailed.¹⁰

Several consensus present results that are combinations of data from the literature on the frequency of DVT in cases without prophylaxis under different situations. Thus, the following frequencies are reported: 25% in general surgery, 56% in cerebral vascular accident (CVA), 51% in elective surgery of the hip, 50% in trauma, 47% in surgery of the knee, 45% in fracture of the hip, 32% in prostatectomy, 22% in neurosurgery, and 35% in surgery of the spinal column.⁴ In those studies, it is clear that effective prophylaxis is the best strategy. Although accessible, the prophylaxis for DVT is still little used, even in developed countries, as shown by a study published by Goldhaber & Tapson, in which only 1,147 (42%) out of 2,726 patients diagnosed with DVT during hospitalization had received prophylaxis in the 30-day period that preceded the diagnosis.⁶ Similarly, Vallès et al. showed that only 275 (47%) out of 939 surveyed patients received any type of prophylaxis.¹¹

The present study shows an even worse situation: out of 983 patients, only 124 (12.6%) received any type of prophylaxis.

In our environment, similar studies carried out by Engelhorn et al.⁷ and Caiafa & Bastos⁸ showed similar results (Table 4).

Table 4 - Comparison between the present study and the studies carried out by Engelhorn et al.⁷ and Caiafa & Bastos⁸

	With prophylaxis	Without prophylaxis	Appropriate prophylaxis	Inappropriate prophylaxis
	n - %	n - %	n - %	n - %
Schlup et al.	124 (12.61)	859 (87.39)	46 (37.1)	78 (62.9)
Engelhorn et al.7	29 (12.72)	199 (87.28)	Not assessed	Not assessed
Caiafa & Bastos8 *	12.316 (65.9)	6.374 (34.1)	7.388 (59.99)	4.928 (40.01)

* Data from Caiafa & Bastos's study were deducted based on the data presented in the table of their study. As they did not present the same general classification of our study in "appropriate and inappropriate prophylaxis", we had to round the decimal places.

 

A probable justification for the underuse of prophylaxis is the doubts concerning the classification of risk groups and the appropriate indication for each group. Several risk classifications have been published, also called risk scores, some more appropriate for clinical patients and other more suitable for surgical patients (scores of Nicolaides et al.,⁴ Geerts et al.,¹² and Caprini et al.¹³). There are also several current studies showing that there are still many doubts concerning such classifications. Kimmerly et al.¹⁴ published a study showing that there are flaws in patients' risk identification and classification. Risk factors such as immobility and obesity were easily remembered. However, the risk of thrombosis during cancer development was underestimated.¹⁴

Another possibility is the fear of great bleedings, particularly for surgical patients, although it has been proven that the use of prophylactic agents did not increase the risk of bleeding during the procedures.^15,16

Regarding the appropriateness of prophylaxis, it can be observed that, even with several technically appropriate preventive schemes available, both pharmacological and mechanical, they are not always used.

CONCLUSION

Based on the presented data, we conclude that, despite the efficiency of the prophylaxis for DVT having been proven by several studies, it is still little used in our environment.

In our hospital, the medical clinic was the specialty that most used prophylaxis for DVT, but its use has not been satisfactory in any specialty. In more than half of the patients with potential risk for developing DVT, any prophylactic measure was taken and, in half cases in which it was applied, it lacked appropriateness. This study shows the need of a continuous training for physicians and information campaigns at the Institution, in order to solve this problem.

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