Prevention of venous thromboembolism in north america

Prevention of venous thromboembolism in North America: Results of a survey among general sureeons Joseph A. Caprini, MD, Juan I. Arcelus, MD, PhD, Kevin Hoffinan, B A , Tanya Mattern, BS, Maureen Laubach, RVT, Gail P. Size, RVT, Clara I. Traverse, MD, PhD, and Robert Coats, BS, Purpose: The purpose of this study was to analyze current attitudes toward the prevention of postoperative venous thromboembolism among North American general surgeons. Methods: A survey regarding awareness of the problem of venous thromboembolism and preferred modalities of prophylaxis was sent to 3500 randomly selected Fellows of the American College of Surgeons. Results: A total of 1018 (29.1%) surveys was returned. Most of the responding surgeons consider venous thromboembolism a serious health problem. Ninety percent of the surgeons use prophylaxis against venous thromboembolism routinely. The most fre-quently used modalities are intermittent pneumatic compression, low-dose heparin, and elastic stockings. A combination of physical and pharmacologic methods is used by one fourth of respondents, and only 50% start pharmacologic prophylaxis before the surgical procedure. The thrombosis risk factors that are most frequently considered by surgeons when deciding about using prophylaxis are history of venous thromboembolism, immobility, and length of operation. Conclusions: North American surgeons who responded to this survey are well aware of the problem of venous thromboembolism and their approach to prevention has been significantly modified in the last 10 years. Compared with similar European surveys this survey reveals a higher implementation of physical methods such as intermittent pneumatic compression and elastic stockings. Because of the limited response rate and possibility of sampling bias, these findings should be interpreted with caution. (J VASC SUK.G 1994;20:751-8.) hand, the rate of postoperative fatal pulmonary Postoperative venous thromboembolism (VTE) embolism in this population approaches 1%.X represents a serious threat to patients undergoing a During the past 2 decades a large number of studies surgical procedure. It is estimated that 25% of and subsequent metaanalyses of the literature have patients undergoing an abdominal surgical procedure clearly demonstrated that several modalities of pro- experience deep vein thrombosis in the legs, as phylaxis, pharmacologic and physical, are able to sig- detected by objective diagnostic methods, if anti- nificantly reduce the rate of postoperative VTE.1"5 In thrombotic prophylaxis is not provided. On the other 1986 the U.S. National Institutes of Health held a consensus conference that supported the use of some prophylactic methods and provided guidelines for their From the Department of Surgery, The Glcnbrook Hospital, Glenview; and Northwestern University Medical School, indication in different surgical populations. Because Chicago. Presented at the Sixth Annual Meeting of the American the last survey involving North American surgeons was conducted more than 10 years ago,6 the influence of Forum, Maui, Hawaii, Feb. 23-25, 1994. Reprint requests: Joseph A. Caprini, MD, Department of Surgery, that conference on clinical surgical practice is not well The Glcnbrook Hospital, 2100 Pfingsten Rd., Glcnvicw, IL known. The purpose of this study was to assess current attitudes toward postoperative VTE prevention by Copyright 1994 by The Society for Vascular Surgery and means of a survey addressed to a large number of International Society for Cardiovascular Surgery, North American Table II. Modalities of prophylaxis used Table III. Characteristics associated with the main prophylactic methods' IPC, Intermittent pneumatic compression. * Results expressed as average of the reported results (from 1 to 5). questionnaire was sent to 3500 general surgeons use propmlaxis from the United States and Canada who were Fellows of the American College of Surgeons. The list with surgeons' names and addresses was obtained from the American College of Surgeons after a computer-based randomized search for Fellows who were listed as general surgeons was performed. The survey consisted ot 17 questions regarding awareness of the problem of VTE and its risk factors, timing of prophylaxis, and preferred modalities in general and specific clinical scenarios (Appendix 1). AJ1 surveys were mailed with one return addressed, stamped The statistical analysis of the results consisted of the x-square test for proportions. The a level of By July 15, 1993, replies were received from 1018 surgeons (a response rate of 29.1%). Eighty-three percent of the respondents considered VTE a serious or very serious problem, and 86% used specific prophylactic measures, apart from early ambulation, in their patients. Conversely, 146 (14%) surgeons The preferred prophylactic modalities were inter- and elastic stockings (Table II). Regarding the riming mittent pneumatic compression, low-dose heparin, of prophylaxis, pharmacologic or physical methods were started before the operation by 54% and 42% of respondents, respectively. They were continued after the operation by 70% and 64% of surgeons, respectively. Some characteristics associated with the main prophylactic modalities such as safety, efficacy, sim- plicity of use, and cost-effectiveness are detailed in Table III. Seventy-three percent of surgeons have modified their approach to VTE prophylaxis in the past 10 years. The reasons for doing so were the availability of improved physical (54%) and pharmacologic methods (14%), increased awareness of the ^jOjpf0r~—
j O l ' R N A l- <>1- V.VSCU.AR SI R t . H R Y Table V. Recommended modalities in specific clinical scenarios ( % )
•o pvphvla.™ ,% i Stockings < '"a • ire Combination indicates combination of physical and pharmacologic modalities. IPC, Intermittent pneumatic compression; VTE, venous thromboembolism. problem (40%), and concerns about liability issues (p = 0.07), hospital capacity (p = 0.7), or city Risk factors considered more important when deciding about adopting prophylaxis are presented in Table IV. The recommended modalities for specific Several surveys performed in different countries clinical situations are depicted in Table V'. The results during the past 10 years reveal marked differences regarding which is the first diagnostic test ordered to among general surgeons in their attitudes toward confirm a suspected deep vein thrombosis were B- VTE prevention.6 "lj Furthermore, surgeons' prefer- mocie ultrasonography (64%) followed by handheld ences have changed through the vears as new Doppler (17%), contrast venography (12%), and methods have developed. This has been documented Most ot the responding surgeons performed by Bergqvist,13 who analvzed the results of three general abdominal surgical procedures (83%), ab- different surveys conducted in Sweden within 10 dominal wall hernia surgical procedures (66%), colo- years. This author reported an increase in the rectal surgical procedures (60%), and laparo-scopic proportion of clinics using some form of prophylaxis, surgical procedures (56%). Only 10% performed from 81% in 1977 to 1978 to 100% in 1987 to 1988. vascular procedures. The capacity of the hospitals The 29% response rate obtained in our study is where surgeons practiced was fewer than 200 beds in very similar to that reported before in the United 30% of the cases, between 200 and 500 beds in 46%, States in general (30%),6 in orthopaedic surgery and more than 500 beds in 24%. Forty-nine percent of (19%),u and more recently, in Australia and New- respondents worked in a teaching hospital, and 50% Zealand (28.%).12 Such a low response rate is of had an academic appointment. Twenty percent had concern, because it might lead to notable bias when been in practice for less than 10 years, 34% between analyzing the results, such as self-selection of respon- 10 and 20 years, 28% between 21 and 30 years, and dents. One could argue that diose returning the survev 18% more than 30 years. Most of the respondents were biased either by believing in prophylaxis or were practiced in cities with a population less than 100,000 interested in having their opinion heard. The views of (41%) inhabitants, and 37% did so in areas between most physicians were not heard, because they chose to ignore the survey. In addition, surgeons who are not The use of prophylaxis was significantly higher very knowledgeable about prophylaxis might have among surgeons practicing in teaching hospitals been less likely to respond. As shown in Table VI, (91%) than those who did"not (84%) (p < 0.05). surveys addressed to surgical depart-ments7'9"11'13 However, the implementation of prophylaxis did not yielded higher response rates than did those addressed to show significant differences related to surgeons' individual surgeons.6'S-!2 Nevertheless we hoped that by academic appointment (p = 0.24), years in practice addressing the questionnaires to individual surgeons, we would obtain a J O U R N A I . < > H VASCULAR s U R ( . , h R \ Table VI. Summon' of surveys on prevention of venous thromboembolism ' L >v ••}! ?ropl}vla.\':s i % J more reliable estimate of the average general s u r - laxis. Pot example, though the last Swedish survey geon's routine clinical practice. Another shortcoming indicated that 100% of the general surgical depart- of this survey is die fact that most surgeons com- ments used prophylaxis, only 37% of patients who pleted the questionnaire without researching indi- underwent a surgical procedure were receiving pro- vidual charts or patient records. What is the exact phylaxis. li5 Two studies conducted in the United percentage of a surgeon's patients receiving each States, one prospective13 and another retrospective,16 prophylactic modality, and for how long? Unfortu- found that the proportion of patients who underwent a nately it is difficult to obtain this type of information surgical procedure and were given prophylaxis \vas without a thorough review of individual records. Most surgeons responding to our survey are well In general the preferred thromboprophylactic aware of the problem of postoperadve VTE. This is modalities were elastic stockings, low-dose heparin, reflected by 86% of respondents currently using and intermittent pneumatic compression (Table II). specific prophylactic methods in their patients, com- These results are similar to those from the 1982 pared with 73% in 1982.6 Such a rate is similar to that American survey.6 However, tiiere is an increase in found in some European studies9'11 and is higher than the frequency of use of intermittent pneumatic in Australia and New Zealand12 and the United compression. The high implementation of physical methods in North America has also been reported in Prophylaxis was used in a significantly higher Australia and New Zealand12 and the United King- proportion by surgeons practicing in teaching hos- dom8 but not in other European countries.9-u'13 pitals. Yet statistically significant differences were not It is surprising to note die relatively high propor- associated with other variables such as years in tion of general surgeons who were using aspirin for practice, academic appointment, or capacity of the their patients undergoing general surgical procedures, despite die National Institute of Health consensus It is interesting to note that very few respondents conference reservations about die benefits associated did not use prophylaxis because of the risk derived with die use of diis drug.1' Similar high rates of from its complications or because they considered die aspirin use have been reported in other recent surveys.12'13 incidence of VTE too low to justify the adoption of As shown in Table III, respondents considered prophylaxis (Table I). Whereas 73% of surgeons heparin and intermittent pneumatic compression to expressed doubts about die efficacy of available be the most effective methods and stockings less preventive mediods in 1982,6 this percentage was effective. Physical mediods were rated as safe and reduced to 5% in this survey. This probably reflects simple to use, whereas oral anticoagulants obtained the influence of the large number of studies published in low average ratings. Regarding cost-effectiveness, recent years demonstrating the efficacy of prophylaxis. heparin and stockings obtained the best scores. It is important to realize that the proportion of Most responding surgeons have modified their surgeons expressing in a survey that they implement approach to VTE prevention in die last 10 years. The prophylaxis does not necessarily parallel the proportion main reasons for diis change are die availability of of patients who actually receive such prophy- improved physical methods followed by increased lOl'RNAl. 01-' \'ASCt'I.AR SL'IUIHRV
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awareness of the problem. It is s u r p r i s i n g that only should keep in mind that these data reflect die 14% modified t h e i r practice because of improved surgeons' attitudes. In other words the real daily nharmacologic agents and 21% because of concerns current surgical practice could be significantly different about liability. When t h i s survey was mailed, low from these theoretic estimates. In a previous study molecular weight heparin was not available in North conducted at our hospital, we found that the America for clinical use in general surgical procedures. percentage of implementation of prophylaxis was These agents have gained r a p i d acceptance among 76% in patients at high risk. 43% in patients at European surgeons in recent years because of better moderate risk, and 10% in patients at low risk.1'" Those results coincided with this survey's in a very low use of heparin, with only 5% of patients who Regarding risk factor assessment, the low per- were undergoing a surgical procedure receiving this centage of surgeons who consider age an important agent, alone or in combination with other modalities. risk factor is surprising, because a number of studies In summary, and despite the limitations ot this show a clear association between advanced age and an kind of survey, the results of this study indicate that North American surgeons who responded to this Apart from general preferences regarding the use of survey are well aware of the problem of VTE, because different prophylactic modalities in patients un- more surgeons are c u r r e n t l y using some form of dergoing general surgical procedures, we were very prophylaxis for patients at high risk to prevent this interested in assessing the surgeons' options in specific dreadful complication. The approach to prophlaxis clinical scenarios, including patients at high, moderate, has been significantly modified in die last 10 years by a and low risk. As shown in Table V two thirds of the higher implementation of physical methods, especially respondents would implement prophylaxis for patients intermittent pneumatic compression, whereas low- in dieir 50s undergoing conventional cholecysrectomy dose heparin remains the preferred pharmaco-logic through laparotomy. A noticeable preference for agent. A surprising number of patients received aspirin, physical modalities for this surgical population exists, given the negative Literature available and lack of and only 6% of surgeons selected heparin as a single endorsement by the National Institutes of Health. prophylactic modality. For patients of similar age Despite convincing Literature the concept of age as a risk factor was not generally accepted in North laparoscopic approach, a similar proportion of patients America, Australia, or New Zealand. Prophylaxis was would be protected; however, pneumatic compression not widely used in these older individuals unless other was used more frequently, whereas heparin was risk factors were present. In general, responding selected by only 2% of surgeons. This may reflect surgeons achieved a good assessment of die potential reluctance to use anticoagulants in the relatively new thrombotic risk of their patients, and, as a result, field of laparoscopic surgical procedures, where control prophylaxis is being tailored more frequently to die of bleeding problems could be more difficult to achieve. On the other hand, in the clinical scenario of Finally, we realize mat this type of survey is an elderly patient with a history of VTE, heparin was associated with a variety -of problems, and the selected by 10% of respondents and combined information obtained must be interpreted with caution. physical-pharmacologic modalities by 65%. A similar Nevertheless we believe that- this type of analysis is approach was preferred for high-risk colon surgical important and has its place, because it permits procedures. As could be expected, very few surgeons comparisons of U.S. results widi diose obtained in would adopt prophylaxis for local excision of benign other practice settings and different parts of die world. breast lumps. For inguinal hernia repair with patients under epidural anesthesia, 50% of surgeons selected 1. Clagerr GP, Reisch JS. Prevention ot" venous thromboembo- physical modaJities, and only 2% selected heparin. lism in general surgical patients. Ann Surg 1988;208:227-40. These results indicate that when confronted with 2. Colditz GA, Tuden RL, Oster G. Rates of venous thrombosis specific clinical situations, North American surgeons after general surgery: combined results of randomised clinical are very selective in their use of heparin, restricting its use, most of the time, to patients at very high risk in 3. Collins R, Scrimgeur R, Yusuf A, Peto R. Reduction in fatal pulmonary embolism and venous thrombosis by periopcrative administration of subcutaneous heparin. N Engl J Med For patients at moderate risk most surgeons preferred physical modalities. Nevertheless, we 4. Jeffery PC, Nicolaides AN. Graduated elastic stockings in the laxis against venous thromboembolism in adults undergoing hip surgery. Clin Orthop 1987;223:188-93. 5. Pezzuoli G. Serneri GGN, Setrembrini P. et al. Prophvlaxis ot 15. Caprini JA, Arcelus JI, Hasty JH, Tamhane AC, Fabrega F. fatal pulmonary' embolism in genera] surgery' using double- Clinical assessment of venous thromboembolic blind, randomized, controlled, clinical trial versus placebo surgical patients. Semin Thromb Hemost 1991;17:304-12. 16. Anderson FA, Wheeler HB, Goldberg RJ. Hosmer D\V. 6. Conti S, Daschbach M. Venous thromboembolism prophylaxis: Forcier A, Pathwardahn N'A. Physician practices in the a survey ot its use in the United States. Arch Surg prevention of venous thromboembolism. Ann Intern Med 7. Bergqvist D. Prevention of postoperative deep 17. National Institutes of Health. Consensus conference on bosis in Sweden: results of a survey. World J Surg 19SO;4: prevention of venous thrombosis and pulmonary embolism. 8. Morris GK. Prevention of venous thromboembolism: a survey 18. Nurmohamed MT, Rosendaal FR, Buller HR, et al. Low- of methods used by orthopedic and general surgeons. Lancet molecular weight heparin versus standard heparin in general and orthopedic surgery: a meta-analysis. Lancet 1992;340: 9. Kobel M, Krahenbuhl B. Enquete sur la pre'vention de la thrombose veineuse profonde en chirurgie. Schweiz Med 19. European Consensus Statement. Prevention of venous throm- 10. Bergqvist D. Prevention of postoperative thromboembolism in 20. Havig O. Deep vein thrombosis and pulmonary embolism: an Sweden: the development of practice during 5 years. Thromb autopsy study with multiple regression analysis of possible risk factors! ActaChir Scand 1977;478S:1-120. 11. Arcelus }I, Traverso CI, Lopcz-Cantarero M, Xavarro F, 21. Nicolaides AN, Irving D. Clinical factors and the risk of deep Perez F, Garcia JM. Actitud ante la enfermedad tromboem- venous thrombosis. In: Nicolaides AN, ed. Thromboembo- bolica venosa postoperatoria en los servicios de cirugia lism aetiology, advances in prevention and management. 1st 12. Fletchcr JP, Koutts }, Ockelford PA. Deep vein thrombosis 22. Lowe GDO, McArdle BM, Carter DC, et al. Prediction and prophylaxis: a survey of current practice in Australia and New selective prophylaxis of venous thrombosis in elective gas- trointestinal surgery. Lancet 1982;1:409-12. 13. Bergqvist D. Prophylaxis against postoperative venous thromboembolism: a survey of surveys. Thromb Haemorrh 1990;2:69-73. Submitted March 12, 1994; accepted May 8, 1994. 14. Paiennent GD, Wessinger SJ, Harris WH. Survey of prophy- iOl'RNAl dl- V.W I ' l . A R Sl'Rt'.KRY Volume 20. Ni;:y.hcr 5 APPENDIX: THROMBOSI§ PROPHYLAXIS SURVEY IN GENERAL HCW WOULD VOU °ATE THE PROBLEM OF VENOUS 7. PLEASE ASSESS THE CHARACTERISTICS ASSOCIATED WITH EACH THROMBOSIS (VTE) AMONG SURGICAL PATIENTS'' PROPHYLACTIC METHOD BY CIRCLING THE APPROPRIATE NUMBER. APART FROM EARLY AMBULATION, DO YOU UTILIZE SPECIAL PRO- PHYLACTIC MEASURES TO PREVENT POSTOPERATIVE VTE? . FOR WHAT REASON(S)? (Check a/I that apply) n Incidence of VTE is low in my experience D Available modalities of prophylaxis are not fully effective D Risk of complications secondary to the 4. WHICH METHOD(S) ARE YOU CURRENTLY IMPLEMENTING? D Foot pneumatic compression D Low-dose oral anticoagulants D Dextran 70 n Fixed doses of low-dose heparin D Combination of physical and pharmacologic 8. HAVE YOU MODIFIED YOUR APPROACH TO PROPHYLAXIS IN THE 5. WHEN DO YOU USE PHARMACOLOGIC METHODS? (Check all that apply) D Preoperatively D Intraoperatively G Postoperatively D Other 9. IF YOU HAVE. FOR WHAT REASONS? (Check all that apply) n Improved pharmacologic agents n Improved physical methods D Increased awareness n Concerns about 1 0 . IF YOU WERE CONSIDERING WHETHER OR NOT TO UTIUZE VTE PROPHYLAXIS FOR A PATIENT. WHICH THREE FACTORS ARE MOST _ Length of surgical procedure _ History of previous thrombosis _ Blood disorder (hypercoagulability) _ Other 11. FOLLOWING is A LIST OF THE MODAUTIES OF VTE PROPHYLAXIS CURRENTLY AVAILABLE IN THIS COUNTRY. PLEASE INDICATE WHICH ONE(S) YOU WOULD RECOMMEND IN THE CLINICAL SITUATIONS THAT ARE DESCRIBED ON THE OPPOSITE PAGE. (Forexample, ifin the first case you decided to recommend elastic stockings plus low-dose heparin, you should indicate B and D.) 13. PLEASE INDICATE WHICH GENERAL CATEGORIES OF SURGICAL PROCEDURES ARE MOST COMMON IN YOUR PRACTICE. (Check 3/1 that
apply) G General abdominal surgery D Hernia repair D Colo-rectal surgery Q Laparoscopic surgery D Other _ 55-year-old woman undergoing elective cholecys- tectomy through conventional laparotomy, without 1 4 . WHAT is THE CAPACITY OF THE HOSPITAL AT WHICH YOU _ 75-year-old man scheduled for colon resection for rectal carcinoma, with a history of congestive heart failure. _ 24-year-old woman who needs excisional biopsy for a breast fibroadenoma and without additional risk 1 5 . IS THIS HOSPITAL A TEACHING HOSPITAL. OR AFFILIATED WITH A
_ 47-year-old woman scheduled for laparoscopic cholecystectomy without additional risk factors. _ 78-year-old woman with acute cholecystitis undergoing 1 6. DO YOU HAVE AN ACADEMIC APPOINTMENT? laparoscopic cholecystectomy. The patient has severe varicose veins and a history of deep vein 1 7. HOW MANY YEARS HAVE YOU BEEN IN PRACTICE? _ 60-year-old man scheduled for repair of indirect inguinal hernia under epidural anesthesia and without _ 54-year-old obese woman presenting with acute 18. WHAT is THE POPULATION OF THE CITY IN WHICH YOU PRACTICE? abdominal pain suggestive of acute appendicitis and (If you practice in a suburb of a large city, please refer to the larger metropolitan area.) D 0 - 20,000 D YOUR PRACTICE, WHAT IS THE FIRST TEST YOU ORDER FOR 20,000 - 100,000 D 100,000 - 500,000 D 500,000- SUSPECTED DVT?
D B-mode ultrasonography (Duplex) D Outflow plethysmography D Venogram

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