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Communications to the Editor |

Risks vs Benefits in Total Joint Surgery Risks vs Benefits in Total Joint Surgery FREE TO VIEW

Paul A. Lotke, MD
Author and Funding Information

Affiliations: University of Pennsylvania Medical Center, Philadelphia, PA,  Mayo Clinic, Rochester, MN

Correspondence to: Paul A. Lotke, MD, Department of Orthopedic Surgery, University of Pennsylvania Medical Center, 3400 Spruce St, Philadelphia, PA 19104-4283



Chest. 1999;116(3):843-845. doi:10.1378/chest.116.3.843-b
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To the Editor:

As you are aware, there is considerable controversy regarding the best methods to prevent venous thromboembolism (VTE). The recommendations published in the article by Clagett et al (November 1998 supplement)1may have a great effect on medical decision making, economics, and legal issues concerning this subject, and, thus, the grade A1 recommendations of the authors may make it very difficult to utilize alternative regimens. As an advocate for the use of aspirin as prophylaxis for VTE in total knee and hip replacement surgery, I am always on the defensive. Yet, our data and those of others in England and Europe24 show that death rates with the use of aspirin or with no prophylaxis are the same as those with the use of low-molecular-weight heparin, warfarin, or both (ie, 0.1 to 0.2%). In reality, it is fatal or symptomatic pulmonary emboli (PEs) that are the focus of all of our efforts in the area of prophylaxis.

Claggett et al1 noted that their information “suggests that asymptomatic DVT [deep venous thrombosis] discovered by venography may not be an appropriate surrogate measure for the major efficacy and point of interest, symptomatic VTE and fatal PE.” Yet, at the same time that they made this statement, they were making all of their recommendations based on those asymptomatic venographic data.

In medical patients with carcinomatosis, congestive heart failure, or coagulopathies, the presence of calf thrombi is ominous and, indeed, is prognostic for a potential PE. However, after the orthopedic surgeon kinks, compresses, places tourniquets on, pulls, and traumatizes the lower extremity for over an hour and after the patient develops a clot in this extremity, the prognostic significance of that clot may be different. Therefore, to use an asymptomatic clot formed after total hip or total knee replacement surgery to determine the risk for PE may be inappropriate.

I suggest that using a DVT as a marker after total hip or total knee replacement surgery may be misleading and that markers for some state of hypercoagulation would be more accurate. If such markers could be conveniently identified, then the utilization of risky, expensive, and invasive prophylactic anticoagulation regimens could be more easily justified. However, recommending prophylaxis that exposes all of our patients to a significantly increased risk of bleeding in the postoperative period may not be appropriate.

I believe that sufficient modifiers should be included in the recommendations of Clagett et al to allow for divergent opinions to be comfortably expressed and accepted for use.

Clagett, GP, Anderson, FA, Jr, Geerts, W, et al (1998) Prevention of venous thromboembolism.Chest114(suppl),531S-560S
 
Ansari, S, Warwick, D, Ackroyd, CT, et al Incidence of fatal pulmonary embolism after 1390 knee arthroplasties without routine prophylactic anticoagulation, except in high-risk cases.J Arthroplasty1997;12,599-602. [CrossRef]
 
Warwick, D, Williams, MH, Banister, GC Death in throm-boembolic disease after total joint hip replacement.J Bone Joint Surg Br1995;77,6-10
 
Sarmiento, A, Goswami, ADK Thromboembolic prophylaxis with use of aspirin, exercise, and grade elastic stockings, or intermittent compression devices in patients managed with total hip arthroplasty.J Bone Joint Surg Am1999;81A,339-346
 

Risks vs Benefits in Total Joint Surgery

To the Editor:

Dr. Lotke suggests that the “death rate” (presumably from fatal pulmonary embolism) is no different among total hip replacement surgery (THR) or total knee replacement surgery (TKR) patients who receive either no prophylaxis or aspirin prophylaxis compared to patients who receive low molecular weight heparin or warfarin prophylaxis. If this hypothesis is true, then clearly no prophylaxis would be most appropriate since the prophylaxis expense and risk of bleeding would be minimized; for similar reasons, aspirin prophylaxis would be a close alternative. Unfortunately, there are no data to support this hypothesis, and a great deal of data suggest the contrary.

No clinical trials have been reported in which no prophylaxis or aspirin was compared to low molecular weight heparin or warfarin as prophylaxis against fatal pulmonary embolism after THR or TKR. Consequently, Dr. Lotke’s hypothesis has never been adequately tested. Because such a trial would require a very large sample size, the total deep vein thrombosis prevalence as determined by mandatory venography has been used as a surrogate outcome measure. Among control or placebo patients undergoing THR or TKR, the total deep vein thrombosis prevalence is 51% and 61%, respectively.1 Among THR and TKR patients receiving aspirin prophylaxis, the total deep vein thrombosis prevalence for control and placebo patients is 52% and 74%, respectively, providing relative risk reductions of essentially zero for each type of surgery. In contrast, low molecular weight heparin or warfarin prophylaxis provide relative risk reductions of 71% and 57%, respectively, for THR and 49% and 20%, respectively, for TKR. Whereas most of these thrombi are small, asymptomatic, and confined to the deep veins of the calf, in the absence of prophylaxis, between 23% and 36% of THR patients, and between 9% and 20% of TKR patients, have proximal deep vein thrombosis, which imparts a substantially greater risk for symptomatic venous thromboembolism and fatal pulmonary embolism. Although isolated calf vein thrombosis can propagate to involve the proximal deep veins, most such thrombi resolve without apparent clinical sequelae. Consequently, using the prevalence of total deep vein thrombosis (as determined by mandatory venography at the time of hospital discharge) as the primary outcome measure tends to magnify the severity of the problem. Nevertheless, this outcome measure remains appropriate for comparing the efficacy of different prophylaxis methods.

We agree with Dr. Lotke that the benefits (effectiveness) of any prophylaxis regimen should be weighed against the costs, both in terms of the bleeding complications and the costs of failed prophylaxis (eg, venous thromboembolism and death). This comparison is best performed via a formal cost-effectiveness analysis.2 All cost-effectiveness analyses comparing prophylaxis to no prophylaxis have found some form of prophylaxis to be more cost effective.35 Only one cost-effectiveness analysis has addressed aspirin prophylaxis in major orthopedic surgery of the leg, and this was confined to patients undergoing THR.3In this analysis, aspirin was marginally more cost effective than warfarin. However, the estimated risk of venous thromboembolism among patients receiving aspirin prophylaxis was substantially lower than the risk reported in subsequent studies. There are no cost-effectiveness analyses of aspirin prophylaxis among patients undergoing TKR. Warfarin prophylaxis is more cost effective than no prophylaxis among patients undergoing THR or TKR, or surgery for hip fracture.4 Similarly, low molecular weight heparin is more cost effective than no prophylaxis among patients undergoing THR.5Finally, either low molecular weight heparin or warfarin are more cost effective in multiple other analyses of either THR610 or TKR.10

Based on the available evidence, we continue to recommend some form of prophylaxis over no prophylaxis for major orthopedic surgery of the leg; low molecular weight heparin or warfarin prophylaxis for elective THR; and low molecular weight heparin, warfarin, or intermittent pneumatic compression for elective TKR.1

References
Claggett, GP, Anderson, FA, Jr, Geerts, W, et al Prevention of venous thromboembolism.Chest1998;114 (suppl),5315-5605
 
Eddy, DM Principles for making difficult decisions in difficult times.JAMA1994;271,1792-1798. [CrossRef]
 
Salzman, EW, Davies, GC Prophylaxis of venous thromboembolism.Ann Surg1980;191,207-218. [CrossRef]
 
Oster, G, Tuden, R, Colditz, G A cost-effectiveness analysis of prophylaxis against deep-vein thrombosis in major orthopedic surgery.JAMA1987;257,203-208. [CrossRef]
 
Bergqvist, D, Lindgren, B, Mätzsch, T Comparison of the cost of preventing postoperative deep vein thrombosis with either unfractionated or low molecular weight heparin.Br J Surg1996;83,1548-1552. [CrossRef]
 
Anderson, DR, O’Brien, BJ, Levine, MN, et al Efficacy and cost of low-molecular-weight heparin compared with standard heparin for the prevention of deep vein thrombosis after total hip arthroplasty.Ann Intern Med1993;119,1105-1211. [CrossRef]
 
Drummond, M, Aristides, M, Davies, L, et al Economic evaluation of standard heparin and enoxaparin for prophylaxis against deep vein thrombosis in elective hip surgery.Br J Surg1994;81,1742-1746. [CrossRef]
 
O’Brien, BJ, Anderson, DR, Goeree, R Cost-effectiveness of enoxaparin versus warfarin prophylaxis against deep-vein thrombosis after total hip replacement.Can Med Assoc J1994;150,1083-1090
 
Menzin, J, Colditz, GA, Regan, MN, et al Cost-effectiveness of enoxaparin versus low-dose warfarin in the prevention of deep-vein thrombosis after total hip replacement surgery.Arch Intern Med1995;155,757-764. [CrossRef]
 
Hull, RC, Raskob, GE, Pineo, GF, et al Subcutaneous low-molecular-weight heparin vs warfarin for prophylaxis of deep vein thrombosis after hip or knee implantation: an economic perspective.Arch Intern Med1997;157,298-303. [CrossRef]
 

Figures

Tables

References

Clagett, GP, Anderson, FA, Jr, Geerts, W, et al (1998) Prevention of venous thromboembolism.Chest114(suppl),531S-560S
 
Ansari, S, Warwick, D, Ackroyd, CT, et al Incidence of fatal pulmonary embolism after 1390 knee arthroplasties without routine prophylactic anticoagulation, except in high-risk cases.J Arthroplasty1997;12,599-602. [CrossRef]
 
Warwick, D, Williams, MH, Banister, GC Death in throm-boembolic disease after total joint hip replacement.J Bone Joint Surg Br1995;77,6-10
 
Sarmiento, A, Goswami, ADK Thromboembolic prophylaxis with use of aspirin, exercise, and grade elastic stockings, or intermittent compression devices in patients managed with total hip arthroplasty.J Bone Joint Surg Am1999;81A,339-346
 
Claggett, GP, Anderson, FA, Jr, Geerts, W, et al Prevention of venous thromboembolism.Chest1998;114 (suppl),5315-5605
 
Eddy, DM Principles for making difficult decisions in difficult times.JAMA1994;271,1792-1798. [CrossRef]
 
Salzman, EW, Davies, GC Prophylaxis of venous thromboembolism.Ann Surg1980;191,207-218. [CrossRef]
 
Oster, G, Tuden, R, Colditz, G A cost-effectiveness analysis of prophylaxis against deep-vein thrombosis in major orthopedic surgery.JAMA1987;257,203-208. [CrossRef]
 
Bergqvist, D, Lindgren, B, Mätzsch, T Comparison of the cost of preventing postoperative deep vein thrombosis with either unfractionated or low molecular weight heparin.Br J Surg1996;83,1548-1552. [CrossRef]
 
Anderson, DR, O’Brien, BJ, Levine, MN, et al Efficacy and cost of low-molecular-weight heparin compared with standard heparin for the prevention of deep vein thrombosis after total hip arthroplasty.Ann Intern Med1993;119,1105-1211. [CrossRef]
 
Drummond, M, Aristides, M, Davies, L, et al Economic evaluation of standard heparin and enoxaparin for prophylaxis against deep vein thrombosis in elective hip surgery.Br J Surg1994;81,1742-1746. [CrossRef]
 
O’Brien, BJ, Anderson, DR, Goeree, R Cost-effectiveness of enoxaparin versus warfarin prophylaxis against deep-vein thrombosis after total hip replacement.Can Med Assoc J1994;150,1083-1090
 
Menzin, J, Colditz, GA, Regan, MN, et al Cost-effectiveness of enoxaparin versus low-dose warfarin in the prevention of deep-vein thrombosis after total hip replacement surgery.Arch Intern Med1995;155,757-764. [CrossRef]
 
Hull, RC, Raskob, GE, Pineo, GF, et al Subcutaneous low-molecular-weight heparin vs warfarin for prophylaxis of deep vein thrombosis after hip or knee implantation: an economic perspective.Arch Intern Med1997;157,298-303. [CrossRef]
 
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