Factor V Leiden (G1691A) and Prothrombin Gene G20210A Mutations as Potential Risk Factors for Venous Thromboembolism after Total Hip or Total Knee Replacement Surgery

Risk of recurrent venous thromboembolism or bleeding in relation to thrombophilic risk factors in patients receiving ximelagatran or placebo for long-term secondary prevention of venous thromboembolism

The impact of prothrombotic abnormalities on the risk of recurrent venous thromboembolism (VTE) and bleeding in patients receiving long-term anticoagulation remains unclear. This analysis evaluated the influence of potential prothrombotic risk factors (antithrombin, protein C, protein S, factor V Leiden mutation, prothrombin gene G20210A mutation, cardiolipin antibodies, number of risk factors) on the risk of recurrent VTE or bleeding during treatment with oral ximelagatran (24 mg twice daily) or placebo for 18 months [THRombin Inhibitor in Venous thromboEmbolism (THRIVE) III trial]. Of the 1223 patients in the intention-to-treat population, prothrombotic state was analysed in 559 patients receiving ximelagatran and 540 patients receiving placebo. It is possible that patients at a high risk of recurrent VTE were poorly represented in this analysis because of selection bias. Prothrombotic risk factors were reported in 41% of patients (8% had > or = 2 factors). No significant interactions were found between ximelagatran treatment and potential prothrombotic risk factors for the risk of recurrent VTE or bleeding by Cox proportionate hazard modelling. There was no clear evidence for a higher risk of recurrent VTE or bleeding across subgroups according to the potential prothrombotic factors analysed in this study.

The John Charnley Award: heritable thrombophilia and development of thromboembolic disease after total hip arthroplasty

We retrospectively assessed whether heritable thrombophilia-hypofibrinolysis was more common in patients developing venous thromboembolism after total hip replacement than among control patients who did not develop venous thromboembolism, as an approach to better identify causes of venous thromboembolism after total hip arthroplasty. Twenty patients with proximal deep venous thrombosis after THA and 23 patients with symptomatic pulmonary embolism were compared with 43 control patients who did not have postoperative venous thromboembolism. Five of 42 patients with venous thromboembolism (12%) and 0 of 43 control patients (0%) had antithrombin III deficiency (< 75%). Nine of 42 patients with venous thromboembolism (21%) and 2 of 43 control patients (4.7%) had protein C deficiency (< 70%). Ten of 43 patients with venous thromboembolism (9 heterozygous, 1 homozygous; 23%) and 1 of 43 control patients (heterozygous; 2%) had the prothrombin gene mutation. Patients who had venous thromboembolism after total hip arthroplasty were more likely than matched control patients to have heritable thrombophilia with antithrombin III or protein C deficiency, or homo-heterozygosity for the prothrombin gene mutation. Screening for these three tests of heritable thrombophilia before total hip arthroplasty should improve the identification of patients with a reduced risk of venous thromboembolism who may need only mild thromboprophylaxis, and of those patients with heritable thrombophilia in whom prophylaxis should be more aggressive.

LEVEL OF EVIDENCE

Prognostic study, Level II-1 (lesser-quality RCT). See the Guidelines for Authors for a complete description of levels of evidence.

Venous thromboembolic prophylaxis after elective total hip arthroplasty

Elective total hip arthroplasty is a common orthopaedic procedure that has been proven to relieve pain and reliably improves the quality of life of its patients. However, patients having a total hip arthroplasty are among those at greatest risk for venous thromboembolic disease. Therefore, most orthopaedic surgeons use routine prophylaxis. Although several agents have been shown to reduce the risk of thromboembolic disease, there is no clear preference for a particular agent in elective total hip arthroplasty. This evidence-based review focuses on the efficacy and safety of the agents that currently are used for prophylaxis against deep venous thrombosis. These agents include warfarin, low-molecular-weight heparin, fondaparinux, aspirin, and mechanical devices. Furthermore, the influence of shorter hospital stays on duration of prophylaxis and screening will be discussed. The most effective prophylactic agents for patients after total hip arthroplasty include low-molecular-weight heparin, warfarin, and fondaparinux. Pneumatic compression devices have been proven to reduce distal thromboembolic events but multi-center, randomized studies need to be done to determine the efficacy of mechanical prophylaxis with short hospital stays. The selection of a prophylaxis regimen is a balance between efficacy and safety, and individual patient factors can influence the prophylaxis regimen that is used.

Living-donor kidney transplantation: a review of the current practices for the live donor

The first successful living-donor kidney transplant was performed 50 yr ago. Since then, in a relatively brief period of medical history, living kidney transplantation has become the preferred treatment for those with ESRD. Organ replacement from either a live or a deceased donor is preferable to dialysis therapy because transplantation provides a better quality of life and improved survival. The advantages of live versus deceased donor transplantation now are readily apparent as it affords earlier transplantation and the best long-term survival. Live kidney donation has also been fostered by the technical advance of laparoscopic nephrectomy and immunologic maneuvers that can overcome biologic obstacles such as HLA disparity and ABO or cross-match incompatibility. Congressional legislation has provided an important model to remove financial disincentives to being a live donor. Federal employees now are afforded paid leave and coverage for travel expenses. Candidates for renal transplantation are aware of these developments, and they have become less hesitant to ask family members, spouses, or friends to become live kidney donors. Living donation as practiced for the past 50 yr has been safe with minimal immediate and long-term risk for the donor. However, the future experience may not be the same as our society is becoming increasingly obese and developing associated health problems. In this environment, predicting medical futures is less precise than in the past. Even so, isolated abnormalities such as obesity and in some instances hypertension are no longer considered absolute contraindications to donation. These and other medical risks bring additional responsibility in such circumstances to track the unknown consequences of a live-donor nephrectomy.

A single-centre prospective study of clinical and haemostatic risk factors for venous thromboembolism following lower limb arthroplasty

Previous studies report conflicting results concerning the potential significance of thrombophilic genotypes in postarthroplasty venous thromboembolism (VTE). This study assessed thrombophilic genotypes, haemostatic and clinical variables as independent risk factors for VTE postarthroplasty. A total number of 569 patients undergoing elective lower limb arthroplasty at a single centre were prospectively studied. All patients were interviewed and had blood samples collected preoperatively. Bilateral lower limb ultrasonography was performed at day 7 +/- 2 postoperatively in all patients (ventilation/perfusion lung scanning in symptomatic patients only). The incidence of inhospital postoperative VTE was 26%. In univariate analysis - increased age, knee arthroplasty, recent surgery, general anaesthesia, shorter operation time, non-receipt of blood transfusion and differences in surgical practice (including use of pneumatic calf compression, surgical drains and postoperative bandaging techniques) were significantly associated with VTE. Factor V Leiden, prothrombin G20210A and MTHFR C677T mutations were not significant risk factors for VTE, and of all haemostatic variables tested, only median activated partial thromboplastin time showed significant difference between VTE and non-VTE patients (34 s vs. 33 s). Multiple logistic regression analysis demonstrated that increased age, knee arthroplasty and individual surgeon's routine practices were the only significant independent risks for VTE; hence routine preoperative blood screening for a potential hypercoaguable state is not indicated in this surgical setting.

Factor V Leiden and perioperative risk

Factor V Leiden (FVL) is the most common known inherited cause of thrombophilia; it is present in approximately 5% of the Caucasian population. Although the risk of venous thrombosis associated with this polymorphism in various medical settings is well described, its effect on perioperative risk is only beginning to be explored. Specifically, there are few studies addressing the potential risks of FVL in the surgical population, in which both hemorrhagic and thrombotic complications convey substantial clinical and economic significance. There are speculations and unproven hypotheses regarding FVL in this population, and these therefore highlight the need to comprehensively address this issue. This review will describe the physiology of the FVL mutation, briefly clarify its risk in the nonsurgical setting, and assess current data regarding FVL in noncardiac and cardiac surgery. Finally, a summary of current clinical evidence and a plan for more detailed investigation of this potentially significant risk factor will be proposed.

Risk factors for venous thromboembolism after total hip and knee replacement surgery

Elective total hip and total knee arthroplasty surgeries are associated with an extraordinarily high incidence of asymptomatic venous thromboembolism (VTE). Symptomatic deep vein thrombosis (DVT) or pulmonary embolism (PE) is diagnosed in only 2%-4% of these patients. A number of studies have defined the incidence and time course of symptomatic thromboembolism after these procedures. Knee arthroplasty is associated with a very high incidence of asymptomatic calf vein thrombosis, with almost all symptomatic VTE events diagnosed in the first 21 days after surgery. Hip arthroplasty, however, is associated with a higher incidence of asymptomatic proximal thrombi and a modestly higher incidence of symptomatic VTE events, many diagnosed up to 6 or 8 weeks after hospital discharge. Extended medical thromboprophylaxis has been shown to reduce the incidence of symptomatic and asymptomatic VTE among hip arthroplasty patients but not among knee arthroplasty patients. Risk factors for VTE after knee arthroplasty are not well defined. Important risk factors that have been shown to be associated with the development of VTE after hip surgery include (1) a history of prior VTE, (2) obesity (body mass index > 25), (3) delay in ambulation after surgery, and (4) female sex. Factors associated with lower risk include (1) Asian/Pacific Islander ethnicity, (2) use of pneumatic compression among non-obese patients after surgery, and (3) extended thromboprophylaxis after hospital discharge.