SEMINARS IN THROMBOSIS AND HEMOSTASIS—VOLUME 17, NO. 4, 1991
International Perspective on Venous Thromboembolism Prophylaxis in Surgery
During the past 15 years, many studies have proved the efficacy of various modalities in preventing the development of venous thromboembolism (VTE) in surgical patients. The influence exerted by these investigations on the current practice of surgeons regarding VTE is not well known. In fact, several surveys performed in Europe and the United States during the last 10 years reveal marked differences in the attitudes of surgeons practicing in different countries.1-6 Furthermore, their preferences for one or another modality have changed with the years as new methods developed. In order to improve and implement prophylaxis among surgical patients, it is important not only to prove its safety and efficacy in preventing VTE, but also to contemplate surgeons' awareness about VTE, their reasons for using or not using prophylaxis, and the adjustment of prophylaxis to the patient's level of risk. This can be accomplished by reviewing the opinions and practices expressed by the surgeons' answers to surveys.
PROPHYLAXIS IN GENERAL SURGERY According to the results of the surveys shown in Table 1, more general surgeons are adopting prophylaxis for their patients in recent years4,5 than they did 5 to 10 years ago. 1-3 In Sweden, Bergqvist2,4 estimated the proportion of surgical patients receiving prophylaxis and found an increase from 19% in 1977 to 25% in 1982. When evaluating these data, it is important to differentiate between questionnaires sent to individual
From the Department of Surgery, Glenbrook Hospital, Glenview, Illinois and Northwestern University Medical School, Chicago, Illinois. Reprint requests: Dr. Arcelus, Department of Surgery, Glenbrook Hospital, 2100 Pfingsten Road, Glenview, IL 60025. 322
surgeons and those sent to surgical services, because this influences the results. When surveys from individual surgeons were reviewed, prophylaxis was used in 62 to 73% of patients. When surgical services responded, however, compliance rose to 80 to 99%. In the Spanish survey, the global implementation will fall from 80 to 57% if patients over 40 years old with any other risk factor are considered, instead of the adoption of prophylaxis by the surgical service.5 Another important aspect to consider when reviewing a survey is whether a question on routine or any prophylaxis is specifically asked. This could explain the low rate of prophylaxis (62%) found by Morris among British surgeons, when asking about routine prophylaxis for patients aged 40 and over.1 The preferred modalities among general surgeons are heparin, physical methods such as graduated stockings and intermittent pneumatic compression, and dextran (Table 2). There are remarkable differences among the surveys regarding the most frequently used methods. Although heparin was the most widely used method in some European countries,1,5 dextran was the most frequently used method in Sweden.2,4 Physical methods were applied by 36% of the American surgeons, followed by heparin (32%) in the 1982 survey.3 At that time, TABLE 1. Implementation of Prophylaxis Among General Surgeons Frequency Reference
Year
Country
Bergqvist2
1980
Sweden
81*
Morris1
1980
UK
62†
Conti and Daschbach 3
1982
USA
73†
Bergqvist4
1985
Sweden
99*
Arcelus et al 5
1988
Spain
80*
* Surveys sent to surgical services. †Surveys sent to individual surgeons.
Copyright © 1991 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
Downloaded by: Universite Laval. Copyrighted material.
JUAN I. ARCELUS, M.D., Ph.D., JOSEPH A. CAPRINI, M.D., F.A.C.S., and CLARA I. TRAVERSO, M.D., Ph.D.
VENOUS THROMBOEMBOLISM PROPHYLAXIS—ARCELUS, CAPRINI, TRAVERSO
USA3†
UK1*
Sweden4‡
Spain5‡
Heparin
32
25
55
80
Dextran
?
5
81
10
Physical
36
9
21
TABLE 3. Implementation of Prophylaxis Among Orthopedic Surgeons
49
* Surveys sent to individual surgeons. † Data refer to moderate-risk patients. ‡ Surveys sent to surgical services.
elastic stockings (32%) were more employed than pneumatic compression (4%) for moderate risk patients. Recently, we have performed a prospective study at our institution involving 535 surgical patients. Our results show that 30% of the patients received a combination of graduated stockings and intermittent sequential compression, 10% received stockings alone, and 5% received low-dose heparin.7 In the British survey, 23% of the surgeons opted for a combination of methods, usually a physical method plus low-dose heparin.1 The results of the Swedish and Spanish surveys, in which more than one option could be selected, indicate that combined prophylaxis was selected in many surgical services for some particular patients. Other less frequently used methods were the combination of heparin and dihydoergotamine (18% in Sweden and 7% in Spain), and oral anticoagulants (13% in Sweden, 1.7% in Spain, and 0% in the United Kingdom).
PROPHYLAXIS IN ORTHOPEDIC SURGERY Orthopedic patients, and more specifically patients undergoing hip surgery, represent one of the groups with a higher risk to develop VTE. Therefore it could be assumed that these patients would receive prophylaxis against VTE more frequently than any other surgical group. When reviewing some surveys performed among orthopedic surgeons (Table 3), one finds that this is not so. In fact, except for the Swedish study,4 the implementation of prophylaxis among these surgeons is comparable to that reported by general surgeons (Tables 1 and 2). Even when 100% of the Swedish orthopedic services used some form of prophylaxis in their orthopedic patients, only 28% of those patients received prophylaxis. This clearly demonstrates that expressing in a survey that prophylaxis is used does not imply that every patient receives such prophylaxis. Hip fracture is associated with a higher risk of VTE than elective total hip replacement (THR). Nevertheless, in the most recent American survey, more surgeons used prophylaxis for THR than for hip fractures.6 It is
Utilization References
Year
Country
(%)
Simon and Stengle8
1974
USA
53†
Bergqvist2
1980
Sweden
96‡
Morris1
1980
UK
Bergqvist4
1985
Sweden
Paiement et al.6
1987
USA
48†
100† 84†
* Surveys sent to individual surgeons. ‡ Surveys sent to surgical services. † Data refer to elective total hip replacement.
encouraging to note how the implementation of prophylaxis among orthopedic surgeons in the United States has increased in the last 11 years from 53 to 84% for THR and from 34 to 74% for hip fracture.6,8 The results of the British survey were disappointing for both THR (48%) and hip fracture (28%).1 In contrast to general surgeons, who clearly prefer heparin or physical methods, orthopedic surgeons use a wider array of modalities (Table 4). During the last decade, there has been a significant reduction in the use of oral anticoagulants (from 47 to 26%) and dextran (from 17 to 7%) among United States orthopedic surgeons.6,8 Conversely, aspirin (23% for both sexes and 5.7% for men only), and heparin at fixed doses (17.5%) have gained wide acceptance, despite the controversial results reported with these methods.9-11 The conclusions of the National Institutes of Health (NIH) Consensus Conference were published in 1986,11 whereas the survey by Paiement and associates6 was performed in 1985. Therefore the results of that survey were not influenced by the NIH recommendations regarding the lack of effectiveness of heparin at fixed doses or aspirin. It is interesting that almost 10% of the American orthopedic surgeons adjusted heparin to partial thromboplastin time for their THR patients,6 as proposed by TABLE 4. Prophylactic Modalities More Frequently Used By Orthopedic Surgeons for Elective Hip Replacement UK1*
Sweden4†
USA6† 27
Modality Heparin
1
16
Dextran
6
81
6
Aspirin
1
5
28
Physical
7
27
7
Oral anticoagulants
3
11
26
* Surveys sent to individual surgeons. † Surveys sent to surgical services.
Downloaded by: Universite Laval. Copyrighted material.
TABLE 2. Prophylactic Modalities More Frequently Used in General Surgery
323
SEMINARS IN THROMBOSIS AND HEMOSTASIS—VOLUME 17, NO. 4, 1991
Leyvraz and associates.12 Conventional heparin was less frequently used by the British1 (7%) and Swedish4 (16%) surgeons. Dextran, again, was the preferred modality in Sweden, followed by physical modalities.4 In the United Kingdom, 20% of the surgeons adopted a combined approach, usually consisting of a physical method plus dextran.1
CURRENT AND FUTURE PERSPECTIVES ON VENOUS THROMBOEMBOLISM PROPHYLAXIS The results of these studies indicate that many surgeons are not using any prophylaxis for many of their patients. What is the reason for this? One could think that fear of bleeding or other complications would be the main argument; yet, if we review the answers stated in some surveys (Table 5), we will realize that this is not necessarily true. Even in the 1980s many general surgeons consider that the low risk of VTE does not justify the adoption of methodical prophylaxis and they express some doubts about the efficacy of the available prophylactic modalities.3-5 Nevertheless, the main reason expressed by 36% of the United States orthopedic surgeons for not using pharmacologic prophylaxis was the risk of bleeding complications. A very important result of this study was that 50% of the surveyed orthopedic surgeons had stopped using warfarin in conventional dosages; most of them (68%) did so after experiencing many bleeding complications.6 It is clear then that the issue is not only developing safer prophylactic modalities, but also persuading surgeons worldwide of the existence of a real need for prophylaxis and showing them that there are effective methods available to prevent VTE, as concluded by the NIH Consensus Conference. So, there seems to be a need for better information and education among surgeons about different aspects of VTE. Even considering when the surveys were done, the conclusion is that the degree of risk is not generally
TABLE 5. Reasons for Not Using Prophylaxis Against Venous Thromboembolism in Surgical Patients USA3*
Sweden4
Spain5
Low incidence of VTE
19%
6.5%
12%
Risk of complications
36%
1.4%
5.3%
Doubts about efficacy
73%
1.8%
3.5%
* These data reflect the agreement of that percentage of surgeons with the statements.
appreciated by surgeons and, even more important, routine practice is mostly at variance with the recommendations of the literature.3,8 Today, according to the NIH Consensus Conference,11 prophylaxis should be tailored to the patient's degree of risk. Are we doing so? The answer is probably no. Some American studies show that 14 to 27% of patients at high risk of developing VTE were receiving a prophylaxis considered effective by the investigators for their condition.3,7,13 At our institution, although 76% of the high-risk patients received some form of prophylaxis, only 10% of those received a combination of physical and pharmacologic modalities, as recently recommended for this group of patients. 14-17 The only way to select the most appropriate prophylaxis for the real needs of a given patient is to assess his or her potential risk of getting VTE. With this purpose, many systems, some of them rather complicated, have been proposed in which different clinical risk factors and laboratory tests are considered. 15,16,18-21 If we pretend to implement risk assessment among surgeons, first we have to design a simple and reliable way to assess that risk. The most accepted systems distribute patients into low-, moderate-, and high-risk categories, according to the previous history of the patient and the type of surgery they are undergoing.15,16,21 The problem is determining the category to which a patient belongs; further studies in this field are desperately needed. The current approach to VTE prophylaxis among surgeons is different for each country. Overall, in the United States there seems to be a lower implementation of pharmacologic prophylaxis in general surgery, whereas physical modalities have been more widely used in recent years.22 In contrast, Western European surgeons prefer pharmacologic modalities. This is especially true for heparin and, in the last 5 years, for the new low molecular weight heparin (LMWH) fractions. In some European countries, health officials are considering enforcing prophylaxis for high-risk patients due to the apparent lack of awareness about VTE among many surgeons. This also could be anticipated in the United States if prophylaxis remains underused despite the official recommendations. Serious medica legal implications may result when a fatal pulmonary embolism occurs in a high-risk patient who did not receive appropriate prophylaxis. Since the publication of the surveys reviewed, there has been significant change in the area of VTE prophylaxis. First, some meta-analyses of the literature have proven the efficacy not only of low-dose heparin but of other modalities.23-25 Second, different LMWH preparations have been compared to unfractionated heparin in well-designed trials. 26-29 The results of these studies suggest that the new heparin fractions could, in the near
Downloaded by: Universite Laval. Copyrighted material.
324
future, replace unfractionated heparin, at least for prophylaxis in specific surgical patients. It should be of great interest to construct a survey designed to assess changes in the clinician's approach to thrombosis prophylaxis as a result of the immense body of recently published data, including the NIH Consensus Conference. If a significant influence could be demonstrated, it will be important to organize an international development conference to unify criteria and define the best possible prophylactic modalities that would achieve a significant reduction in the morbidity and mortality associated with venous thromboembolism in surgical patient.
REFERENCES 1. Morris GK: Prevention of venous thromboembolism. A survey of methods used by orthopedic and general surgeons. Lancet 2:572574, 1980. 2. Bergqvist D: Prevention of postoperative deep vein thrombosis in Sweden. Results of a survey. World J Surg 4:489-495, 1980. 3. Conti S, M Daschbach: Venous thromboembolism prohylaxis: A survey of its use in United States. Arch Surg 117:1036-1040, 1982. 4. Bergqvist D: Prevention of postoperative thromboembolism in Sweden. The development of practice during five years. Thromb Haemost 53:239-241, 1985. 5. Arcelus JI, CI Traverso, M. Lopez-Cantarero, F Navarro, F Perez, JM Garcia: Actitud ante la enfermedad tromboembolica venosa postoperatoria en los servicios de cirugia españoles. Resultados preliminares de una encuesta nacional. Cir Esp 49:394-401, 1988. 6. Paiement GD, SJ Wessinger, WH Harris: Survey of prophylaxis against venous thromboembolism in adults undergoing hip surgery. Clin Orthop 223:188-193, 1987. 7. Caprini JA, JI Arcelus, JH Hasty, A Tamhane, F Fabrega, CI Traverso: Risk assessment of venous thromboembolism in surgical patients. In press. 8. Simon TL, JM Stengle: Antithrombotic practice in orthopedic surgery. Results of a survey. Clin Orthop 102:181-187, 1974. 9. Harris WH, CA Athanasoulis, AC Waltman, EW Salzman: High and low-dose aspirin prophylaxis against venous thromboembolic disease in total hip replacement. J Bone Joint Surg 64A:63-66, 1982. 10. Council on Thrombosis of the American Heart Association: Prevention of venous thromboembolism in surgical patients by low-dose heparin. Circulation 55423A-426A, 1977. 11. National Institutes of Health: Consensus conference on prevention of venous thrombosis and pulmonary embolism. JAMA 256:744— 748, 1986. 12. Leyvraz PF, J Richard, F Bachmann, GV Melle, J-M Treyvaud, J-J Livio, G Candardjis: Adjusted versus fixed-dose heparin in the prevention of deep-vein thrombosis after total hip replacement. N Engl J Med 309:95-958, 1983.
325
13. Wheeler HB, FA Anderson: Venous Thromboembolism: A PublicHealth Perspective. International Symposium on Angiography. John Libbey Publishers, Toulouse, France, 1988. 14. Goldhaber SZ: Venous thromboembolism: How to prevent a tragedy. Hosp Pract 23: 164-174, 1988. 15. Caprini JA, JH Scurr, JH Hasty: Role of compression modalities in a prophylactic program for deep vein thrombosis. Semin Thromb Hemost 14:77-87, 1988. 16. Merli GJ: Prophylaxis for deep vein thrombosis and pulmonary embolism in the geriatric patient undergoing surgery. Clin Geriat Med 6:531-542, 1990. 17. Moser KM: Venous thromboembolism. Am Rev Respir Dis 141:235-249, 1990. 18. Nicolaides AN, D Irving: Clinical factors and the risk of deep venous thrombosis. In: Nicolaides AN, Ed: Thromboembolism: Aetiology, Advances in Prevention and Management. MTP, Lancaster, 1975, pp 193-204. 19. Clayton JK, JA Anderson, GP McNicol: Preoperative prediction of postoperative deep vein thrombosis. Br Med J 2:910-912, 1976. 20. Sue-Ling HM, MJ McMahon, D Johnston, JH Verheijen, C Kluft, PR Philips, J A Davies: Preoperative identification of patients at high risk of deep venous thrombosis after elective major abdominal surgery. Lancet 1:1173-1176, 1986. 21. Hull RD, GE Raskob, J Hirsh: Prophylaxis of venous thromboembolism. Chest 89:374s-383s, 1986. 22. Caprini JA, RA Natonson: Postoperative deep vein thrombosis: current clinical considerations. Semin Thromb Hemost 15:8-13, 1989. 23. Colditz GA, RL Tuden, G Oster: Rates of venous thrombosis after general surgery: Combined results of randomised clinical trials. Lancet 2:143-146, 1986. 24. Collins R, A Scrimgeur, S Yusuf, R Peto: Reduction in fatal pulmonary embolism and venous thrombosis by perioperative administration of subcutaneous heparin. N Engl J Med 318:1162— 1173, 1988. 25. Clagett GP, JS Reisch: Prevention of venous thromboembolism in general surgical patients. Ann Surg 208:227-240, 1988. 26. Turpie AG, MN Levine, J Hirsh, CJ Carter, RM Jay, PJ Powers, M Andrew, RD Hull, M Gent: A randomized controlled trial of a low-molecular-weight heparin (enoxaparin) to prevent deep-vein thrombosis in patients undergoing elective hip surgery. N Engl J Med 315:925-929, 1986. 27. Encke A, K Breddin: Comparison of a low molecular weight heparin and unfractionated heparin for the prevention of deep vein thrombosis in patients undergoing abdominal surgery. Br J Surg 75:1058-1063, 1988. 28. Samama M, JP Boissel S Combe-Tamzali, A Leizirivicz: Clinical studies with low molecular heparins in the prevention and treatment of venous thromboembolism. Ann NY Acad Sci 556:387407, 1989. 29. Bergqvist D, T Matzsch, US Burmak, J Frisell, O Guilbaud, T Hallbook, A Horns, A Lindhagen, H Ljungner, K-G Ljunstrom, H Onarheim, B Risberg, S Torngren, P Ortenwall: Low molecular weight heparin given in the evening before surgery compared with conventional low-dose heparin in prevention of thrombosis. Br J Surg 75:888-891, 1988.
Downloaded by: Universite Laval. Copyrighted material.
VENOUS THROMBOEMBOLISM PROPHYLAXIS—ARCELUS, CAPRINI, TRAVERSO
International Perspective on Venous Thromboembolism Prophylaxis in Surgery
During the past 15 years, many studies have proved the efficacy of various modalities in preventing the development of venous thromboembolism (VTE) in surgical patients. The influence exerted by these investigations on the current practice of surgeons regarding VTE is not well known. In fact, several surveys performed in Europe and the United States during the last 10 years reveal marked differences in the attitudes of surgeons practicing in different countries.1-6 Furthermore, their preferences for one or another modality have changed with the years as new methods developed. In order to improve and implement prophylaxis among surgical patients, it is important not only to prove its safety and efficacy in preventing VTE, but also to contemplate surgeons' awareness about VTE, their reasons for using or not using prophylaxis, and the adjustment of prophylaxis to the patient's level of risk. This can be accomplished by reviewing the opinions and practices expressed by the surgeons' answers to surveys.
PROPHYLAXIS IN GENERAL SURGERY According to the results of the surveys shown in Table 1, more general surgeons are adopting prophylaxis for their patients in recent years4,5 than they did 5 to 10 years ago. 1-3 In Sweden, Bergqvist2,4 estimated the proportion of surgical patients receiving prophylaxis and found an increase from 19% in 1977 to 25% in 1982. When evaluating these data, it is important to differentiate between questionnaires sent to individual
From the Department of Surgery, Glenbrook Hospital, Glenview, Illinois and Northwestern University Medical School, Chicago, Illinois. Reprint requests: Dr. Arcelus, Department of Surgery, Glenbrook Hospital, 2100 Pfingsten Road, Glenview, IL 60025. 322
surgeons and those sent to surgical services, because this influences the results. When surveys from individual surgeons were reviewed, prophylaxis was used in 62 to 73% of patients. When surgical services responded, however, compliance rose to 80 to 99%. In the Spanish survey, the global implementation will fall from 80 to 57% if patients over 40 years old with any other risk factor are considered, instead of the adoption of prophylaxis by the surgical service.5 Another important aspect to consider when reviewing a survey is whether a question on routine or any prophylaxis is specifically asked. This could explain the low rate of prophylaxis (62%) found by Morris among British surgeons, when asking about routine prophylaxis for patients aged 40 and over.1 The preferred modalities among general surgeons are heparin, physical methods such as graduated stockings and intermittent pneumatic compression, and dextran (Table 2). There are remarkable differences among the surveys regarding the most frequently used methods. Although heparin was the most widely used method in some European countries,1,5 dextran was the most frequently used method in Sweden.2,4 Physical methods were applied by 36% of the American surgeons, followed by heparin (32%) in the 1982 survey.3 At that time, TABLE 1. Implementation of Prophylaxis Among General Surgeons Frequency Reference
Year
Country
Bergqvist2
1980
Sweden
81*
Morris1
1980
UK
62†
Conti and Daschbach 3
1982
USA
73†
Bergqvist4
1985
Sweden
99*
Arcelus et al 5
1988
Spain
80*
* Surveys sent to surgical services. †Surveys sent to individual surgeons.
Copyright © 1991 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.
Downloaded by: Universite Laval. Copyrighted material.
JUAN I. ARCELUS, M.D., Ph.D., JOSEPH A. CAPRINI, M.D., F.A.C.S., and CLARA I. TRAVERSO, M.D., Ph.D.
VENOUS THROMBOEMBOLISM PROPHYLAXIS—ARCELUS, CAPRINI, TRAVERSO
USA3†
UK1*
Sweden4‡
Spain5‡
Heparin
32
25
55
80
Dextran
?
5
81
10
Physical
36
9
21
TABLE 3. Implementation of Prophylaxis Among Orthopedic Surgeons
49
* Surveys sent to individual surgeons. † Data refer to moderate-risk patients. ‡ Surveys sent to surgical services.
elastic stockings (32%) were more employed than pneumatic compression (4%) for moderate risk patients. Recently, we have performed a prospective study at our institution involving 535 surgical patients. Our results show that 30% of the patients received a combination of graduated stockings and intermittent sequential compression, 10% received stockings alone, and 5% received low-dose heparin.7 In the British survey, 23% of the surgeons opted for a combination of methods, usually a physical method plus low-dose heparin.1 The results of the Swedish and Spanish surveys, in which more than one option could be selected, indicate that combined prophylaxis was selected in many surgical services for some particular patients. Other less frequently used methods were the combination of heparin and dihydoergotamine (18% in Sweden and 7% in Spain), and oral anticoagulants (13% in Sweden, 1.7% in Spain, and 0% in the United Kingdom).
PROPHYLAXIS IN ORTHOPEDIC SURGERY Orthopedic patients, and more specifically patients undergoing hip surgery, represent one of the groups with a higher risk to develop VTE. Therefore it could be assumed that these patients would receive prophylaxis against VTE more frequently than any other surgical group. When reviewing some surveys performed among orthopedic surgeons (Table 3), one finds that this is not so. In fact, except for the Swedish study,4 the implementation of prophylaxis among these surgeons is comparable to that reported by general surgeons (Tables 1 and 2). Even when 100% of the Swedish orthopedic services used some form of prophylaxis in their orthopedic patients, only 28% of those patients received prophylaxis. This clearly demonstrates that expressing in a survey that prophylaxis is used does not imply that every patient receives such prophylaxis. Hip fracture is associated with a higher risk of VTE than elective total hip replacement (THR). Nevertheless, in the most recent American survey, more surgeons used prophylaxis for THR than for hip fractures.6 It is
Utilization References
Year
Country
(%)
Simon and Stengle8
1974
USA
53†
Bergqvist2
1980
Sweden
96‡
Morris1
1980
UK
Bergqvist4
1985
Sweden
Paiement et al.6
1987
USA
48†
100† 84†
* Surveys sent to individual surgeons. ‡ Surveys sent to surgical services. † Data refer to elective total hip replacement.
encouraging to note how the implementation of prophylaxis among orthopedic surgeons in the United States has increased in the last 11 years from 53 to 84% for THR and from 34 to 74% for hip fracture.6,8 The results of the British survey were disappointing for both THR (48%) and hip fracture (28%).1 In contrast to general surgeons, who clearly prefer heparin or physical methods, orthopedic surgeons use a wider array of modalities (Table 4). During the last decade, there has been a significant reduction in the use of oral anticoagulants (from 47 to 26%) and dextran (from 17 to 7%) among United States orthopedic surgeons.6,8 Conversely, aspirin (23% for both sexes and 5.7% for men only), and heparin at fixed doses (17.5%) have gained wide acceptance, despite the controversial results reported with these methods.9-11 The conclusions of the National Institutes of Health (NIH) Consensus Conference were published in 1986,11 whereas the survey by Paiement and associates6 was performed in 1985. Therefore the results of that survey were not influenced by the NIH recommendations regarding the lack of effectiveness of heparin at fixed doses or aspirin. It is interesting that almost 10% of the American orthopedic surgeons adjusted heparin to partial thromboplastin time for their THR patients,6 as proposed by TABLE 4. Prophylactic Modalities More Frequently Used By Orthopedic Surgeons for Elective Hip Replacement UK1*
Sweden4†
USA6† 27
Modality Heparin
1
16
Dextran
6
81
6
Aspirin
1
5
28
Physical
7
27
7
Oral anticoagulants
3
11
26
* Surveys sent to individual surgeons. † Surveys sent to surgical services.
Downloaded by: Universite Laval. Copyrighted material.
TABLE 2. Prophylactic Modalities More Frequently Used in General Surgery
323
SEMINARS IN THROMBOSIS AND HEMOSTASIS—VOLUME 17, NO. 4, 1991
Leyvraz and associates.12 Conventional heparin was less frequently used by the British1 (7%) and Swedish4 (16%) surgeons. Dextran, again, was the preferred modality in Sweden, followed by physical modalities.4 In the United Kingdom, 20% of the surgeons adopted a combined approach, usually consisting of a physical method plus dextran.1
CURRENT AND FUTURE PERSPECTIVES ON VENOUS THROMBOEMBOLISM PROPHYLAXIS The results of these studies indicate that many surgeons are not using any prophylaxis for many of their patients. What is the reason for this? One could think that fear of bleeding or other complications would be the main argument; yet, if we review the answers stated in some surveys (Table 5), we will realize that this is not necessarily true. Even in the 1980s many general surgeons consider that the low risk of VTE does not justify the adoption of methodical prophylaxis and they express some doubts about the efficacy of the available prophylactic modalities.3-5 Nevertheless, the main reason expressed by 36% of the United States orthopedic surgeons for not using pharmacologic prophylaxis was the risk of bleeding complications. A very important result of this study was that 50% of the surveyed orthopedic surgeons had stopped using warfarin in conventional dosages; most of them (68%) did so after experiencing many bleeding complications.6 It is clear then that the issue is not only developing safer prophylactic modalities, but also persuading surgeons worldwide of the existence of a real need for prophylaxis and showing them that there are effective methods available to prevent VTE, as concluded by the NIH Consensus Conference. So, there seems to be a need for better information and education among surgeons about different aspects of VTE. Even considering when the surveys were done, the conclusion is that the degree of risk is not generally
TABLE 5. Reasons for Not Using Prophylaxis Against Venous Thromboembolism in Surgical Patients USA3*
Sweden4
Spain5
Low incidence of VTE
19%
6.5%
12%
Risk of complications
36%
1.4%
5.3%
Doubts about efficacy
73%
1.8%
3.5%
* These data reflect the agreement of that percentage of surgeons with the statements.
appreciated by surgeons and, even more important, routine practice is mostly at variance with the recommendations of the literature.3,8 Today, according to the NIH Consensus Conference,11 prophylaxis should be tailored to the patient's degree of risk. Are we doing so? The answer is probably no. Some American studies show that 14 to 27% of patients at high risk of developing VTE were receiving a prophylaxis considered effective by the investigators for their condition.3,7,13 At our institution, although 76% of the high-risk patients received some form of prophylaxis, only 10% of those received a combination of physical and pharmacologic modalities, as recently recommended for this group of patients. 14-17 The only way to select the most appropriate prophylaxis for the real needs of a given patient is to assess his or her potential risk of getting VTE. With this purpose, many systems, some of them rather complicated, have been proposed in which different clinical risk factors and laboratory tests are considered. 15,16,18-21 If we pretend to implement risk assessment among surgeons, first we have to design a simple and reliable way to assess that risk. The most accepted systems distribute patients into low-, moderate-, and high-risk categories, according to the previous history of the patient and the type of surgery they are undergoing.15,16,21 The problem is determining the category to which a patient belongs; further studies in this field are desperately needed. The current approach to VTE prophylaxis among surgeons is different for each country. Overall, in the United States there seems to be a lower implementation of pharmacologic prophylaxis in general surgery, whereas physical modalities have been more widely used in recent years.22 In contrast, Western European surgeons prefer pharmacologic modalities. This is especially true for heparin and, in the last 5 years, for the new low molecular weight heparin (LMWH) fractions. In some European countries, health officials are considering enforcing prophylaxis for high-risk patients due to the apparent lack of awareness about VTE among many surgeons. This also could be anticipated in the United States if prophylaxis remains underused despite the official recommendations. Serious medica legal implications may result when a fatal pulmonary embolism occurs in a high-risk patient who did not receive appropriate prophylaxis. Since the publication of the surveys reviewed, there has been significant change in the area of VTE prophylaxis. First, some meta-analyses of the literature have proven the efficacy not only of low-dose heparin but of other modalities.23-25 Second, different LMWH preparations have been compared to unfractionated heparin in well-designed trials. 26-29 The results of these studies suggest that the new heparin fractions could, in the near
Downloaded by: Universite Laval. Copyrighted material.
324
future, replace unfractionated heparin, at least for prophylaxis in specific surgical patients. It should be of great interest to construct a survey designed to assess changes in the clinician's approach to thrombosis prophylaxis as a result of the immense body of recently published data, including the NIH Consensus Conference. If a significant influence could be demonstrated, it will be important to organize an international development conference to unify criteria and define the best possible prophylactic modalities that would achieve a significant reduction in the morbidity and mortality associated with venous thromboembolism in surgical patient.
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VENOUS THROMBOEMBOLISM PROPHYLAXIS—ARCELUS, CAPRINI, TRAVERSO
