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Summary. Subclavian vein thrombosis is a well-recognized complication following central venous catheter insertion and is associated with significant morbidity. The factor V Leiden mutation is an important risk factor for deep venous thrombosis and pulmonary embolism. Whether this mutation also predisposes patients fitted with a central venous catheter to subclavian vein thrombosis is not known. The occurrence of central venous catheter-associated thrombosis was investigated in 277 consecutive patients receiving an allogeneic bone marrow transplantation. All patients received a tunnelled double or triple catheter positioned in the subclavian vein. Catheter-associated thrombosis was diagnosed on the basis of clinical signs of thrombosis, i.e. swelling and/or redness of the limb or venous engorgement and was confirmed with a colour-flow Doppler ultrasound. Thirteen patients were heterozygous for the factor V Leiden mutation. Seven of these patients had a subclavian vein thrombosis (54%), while this occurred in only 9% of the factor V Leiden-negative patients, corresponding with a relative risk of 7·7 (95% CI 3·3–17·9). Factor V Leiden is attributable for 17·3% of all thrombosis in patients with central venous catheters. The majority of patients with the factor V Leiden mutation with a central venous catheter will develop thrombosis. Patients with a factor V Leiden mutation should receive adequate thrombosis prophylaxis upon catheter introduction and the catheter should be removed immediately after the treatment. Based on this very high risk, we advise testing for factor V Leiden in all bone marrow transplantation patients receiving a central venous catheter.
Patients undergoing allogeneic bone marrow transplantation require long-term venous access for the administration of medication, blood products, parenteral hyperalimentation and for blood sampling. For this purpose central venous catheters (CVCs) with a double or triple lumen, mostly Hickman catheters, are implanted. One of the major complications is thrombosis of one of the subclavian veins. Routine venography of asymptomatic patients with an autologous or allogeneic bone marrow transplantation reveals a thrombosis rate that varies from 4% to 42% (Ross et al, 1982; Bozzetti et al, 1983; Haire et al, 1990; Conlan et al, 1991; Boraks et al, 1998). Low-dose warfarin may prevent venous thromboembolism in cancer patients fitted with a central venous catheter (Bern et al, 1990; Boraks et al, 1998). Nevertheless, in a recent study, we did not observe a positive effect of prophylactic low-molecular-weight heparin prophylactic treatment in 382 patients receiving an autologous or allogeneic bone marrow transplantation (Lagro et al, 2000).
Factor V Leiden is currently the most frequent identifiable risk factor for venous thrombosis. Approximately 20% of patients with venous thrombosis are factor V Leiden carriers (Dahlback et al, 1993; Koster et al, 1993a; Svensson & Dahlback, 1994; Voorberg et al, 1994). Factor V Leiden is caused by a guanine to adenine point mutation at nucleotide 1691 of the factor V gene (Bertina et al, 1994). This mutation leads to substitution of the arginine residue at position 506 of the protein by glutamine, which makes a cleavage site in coagulation factor V inaccessible for activated protein C. The frequency of the factor V Leiden mutation in the general population of the Netherlands is 3–5% (Koster et al, 1993b).
This study was undertaken to analyse the influence of the pro-thrombotic factor V Leiden mutation on the frequency of central venous catheter-associated thrombosis in patients receiving an allogeneic bone marrow transplantation.
Patients and methods
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- Patients and methods
Between January 1991 and December 2000, all 299 consecutive patients who underwent allogeneic bone marrow transplantation at the University Hospital Utrecht were included. Pre-bone marrow transplantation DNA was present in 277 patients (93%). The transplantations were performed for different indications as shown in Table I. One hundred and seventy patients were also included in a previous study (Lagro et al, 2000).
Table I. Underlying diseases and kind of bone marrow transplantation in 277 patients.
|Acute myeloid leukaemia||63||(23)|
|Acute lymphoid leukaemia||45||(16)|
|Chronic myeloid leukaemia||63||(23)|
|Type of transplantation|
| Allogenic bone marrow transplantation||227||(82)|
| Allogeneic bone marrow transplantation/ unrelated/HLA-mismatch||50||(18)|
Patients received a tunnelled Hickman catheter (Bard Benelux NV, Nieuwegein, The Netherlands), which was inserted under sterile conditions in the operating room by a rotating group of residents supervised by one of three experienced surgeons. All sibling human leucocyte antigen (HLA)-identical transplanted patients received a double lumen, while patients receiving a HLA-mismatched or unrelated donor transplantation received a triple-lumen catheter. A standard introductory technique was used, consisting of direct puncture of the infraclavicular vein, introduction of a guide wire, radiological confirmation of correct wire position, dilatation of the introductory route, creation of a subcutaneous tunnel and introduction of the catheter with the tip positioned in the superior vena cava. Each lumen was tested for adequate aspiration and infusioncharacteristics, and flushed with heparin-saline (100 IU/ml). Postoperative chest radiography was performed routinely to detect inadvertent pneumothorax and to confirm correct catheter placement. Since January 1996, all patients received thrombosis prophylaxis: a dose of 5700 IU/d of nadroparin s.c. before insertion of the CVC and for a period of 10 d.
All patients received 2 g of cephalotin intravenously 1 h before insertion of the catheter. Catheters were flushed once a day and after every blood withdrawal, administration of medicines and blood products, with 9 ml of 0·9% saline solution followed by 7 ml of heparin (100 IU/ml).
Conditioning therapy consisted of cyclophosphamide and total body irradiation. All patients with a matched-unrelated bone marrow transplantation received low-dose heparin (100 IU/kg; for a period of 4 weeks, starting 5 d before the transplantation) for the prevention of veno-occlusive disease of the liver.
We analysed all catheter-associated thrombosis. In all cases of clinical signs of thrombosis, i.e. swelling and or redness of the limb or venous engorgement, a colour-flow Doppler imaging was performed (Prandoni et al, 1997). In case of persistent clinical signs and a negative ultrasound, the ultrasound was repeated. In patients with a documented thrombus, the catheter was removed and heparin was given intravenously for 5 d, followed by anticoagulant therapy for a period of 3 months. In the case of pulmonary symptoms, radionuclide lung scanning was performed.
Factor V Arg506/Gln506 genotype was determined by polymerase chain reaction (PCR) (Bertina et al, 1994) and hybridization with allele specific oligonucleotides. The allele specific oligonucleotide for factor V Arg506 was 3′-TGGACAGGCAAGGAATAC-5′, and for Factor V Gln506 3′-GGACAGGCGAGGAATAC-5′. Dots were visualized on radiograph films (DuPont, Brussels, Belgium) after overnight radiation (Roest et al, 1999). Some samples were retested by restriction fragment-length polymorphism (RFLP) (Koeleman et al, 1994). The investigator was blinded for presence of thrombotic complications. The physician was not aware of the factor V Leiden status.
A chi-square test was used to compare the frequency of thrombosis in patients with or without low-dose heparin infusion/low-molecular-weight heparin prophylaxis or with double or triple central venous catheters. Freedom from thrombosis was determined on the basis of Kaplan–Meier event-free survival curves. The differences between the groups were evaluated with the log-rank test. The relative risk of thrombosis between factor V Leiden heterozygotes and wild types was obtained using a Cox-proportional hazard model. The endpoint in this model was subclavian vein thrombosis and patients were censored when they died or the catheter was removed. The influence of low-molecular-weight heparin, low-dose heparin and type of catheter on the risk ratio were tested with multivariate analysis. The population-attributable risk was calculated as a parameter for the fraction of thrombotic complications that was attributable to the factor V Leiden mutation (Mietinen, 1974).
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Thirty-three of 277 (12%) patients developed clinical signs of a central venous catheter-associated thrombosis, confirmed by ultrasound (Table II). In two of these patients, the thrombosis was associated with pulmonary embolism. Thirteen patients (4·8%) were found to be heterozygous for the factor V Leiden mutation. No patients were found to be homozygous for the factor V Leiden mutation. Seven out of the 13 factor V Leiden-positive patients (54%) developed a catheter-associated thrombosis, while 9·8% (26 out of 264) of the factor V wild types developed thrombosis (Table II). The mean time to thrombosis in the factor V Leiden-positive patients was 36 ± 37 d compared with 30 ± 24 d in the patients without the mutation (NS). The population-attributable risk of factor V Leiden to thrombosis was 17·3%.
Table II. Central venous catheter thrombosis in allogeneic bone marrow transplantation.
|Factor V Leiden||Catheter-associated thrombosis|
Nine patients out of 94 (11%) without low-molecular-weight heparin prophylaxis developed thrombosis compared with 23 out of 183 receiving low-molecular-weight heparin or low-dose heparin (13%; P = 0·6). The incidence of thrombosis in patients receiving a double- or triple-lumen catheter, was not significantly different: 25 out of 227 double-lumen catheter (11%) vs eight out of 42 triple-lumen catheter (16%). The median time to thrombosis from insertion of the central venous catheter was 32 ± 31 d (range 1–127) and was not influenced by low-molecular-weight heparin prophylaxis, low-dose heparin infusion or the type of catheter (double or triple lumen) (data not shown).
Figure 1 shows the time to thrombosis. The relative risk for thrombosis between the factor V Leiden mutation and the factor V wild types was 7·7 (95% CI 3·3–17·9). Adjustment for low-molecular-weight heparin or low-dose heparin did not affect the risk rates.
Figure 1. Kaplan–Meier event-free survival curves comparing the cumulative percentages of patients in the two groups who did not develop catheter-associated subclavian vein thrombosis.
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This study shows that the pro-thrombotic factor V Leiden mutation is a risk factor for central venous catheter-associated thrombosis in patients receiving an allogeneic bone marrow transplantation. Fifty-four per cent of the factor V Leiden carriers developed subclavian vein thrombosis, compared with 9% of the factor V wild types. The factor V Leiden was responsible for 17·3% of all catheter-associated thromboses. Factor V Leiden carriers had a 7·7-fold increased risk of subclavian vein thrombosis after an allogeneic bone marrow transplantation.
Central venous catheter-associated thrombosis is a serious complication in patients receiving a bone marrow transplantation. There is a high morbidity associated with venous thrombosis and, in addition, a small risk of pulmonary embolism. The catheter needs to be removed in a critical phase when the patient is still aplastic, needs parenteral hyperalimentation, intravenous medication, blood products and frequent blood sampling.
Low-molecular-weight heparin prophylaxis has been used in our hospital since January 1996 for prevention of thrombosis. A previous analysis showed that 10 d of low-molecular-weight heparin prophylactic treatment did not decrease the rate of catheter-associated thrombosis (Lagro et al, 2000). In the current study, we confirmed the lack of a protective role for low-molecular-weight heparin treatment. Low-molecular-weight heparin was given in the first 10 d after catheter introduction. Most of the thrombosis occurred after the first 10 d and prolonged prophylaxis could be beneficial. We did not observe a difference in the rate of thrombosis between the type of catheter: Hickman double or triple lumen. All patients with a triple-lumen catheter received low-dose heparin for 4 weeks infused via the catheter. This regimen also did not prevent the development of thrombosis.
The relative risk of thrombosis between carriers and wild types was independent of prophylactic low-molecular-weight heparin or low-dose heparin treatment. A comparable relative risk between factor V Leiden and venous thrombosis has been observed in the general population: factor V Leiden mutation was associated with an sevenfold increased risk of venous thrombosis in the heterozygotes and an 80-fold increased risk in homozygotes (Koster et al, 1993a; Rosendaal et al, 1995). However, the impact of factor V Leiden was much higher in patients receiving a central venous catheter, because the absolute risk of catheter-associated thrombosis was extremely high (54%) in those patients.
The factor V Leiden analysis was performed in DNA isolated from patients' leucocytes, collected prior to the allogeneic bone marrow transplantation and stored for analysis. Screening for factor V Leiden involves a combination of coagulation and genetic assays (Dahlback et al, 1993; Bertina et al, 1994). The conventional plasma-activated protein C resistance assay will detect circulating factor V synthesized by the liver. Confirmatory genetic analysis employs DNA extracted from peripheral blood leucocytes. This strategy is not applicable to patients who undergo allogeneic bone marrow transplantation because leucocytes are derived from the donor and are therefore not suitable for factor V Leiden mutation confirmation (Parker et al, 2001). Pre-transplantation stored leucocytes/DNA or DNA from buccal mucosa should be used for the genetic test.
New approaches to prevent central venous catheter-associated thrombosis are mandatory. Thrombosis was observed at a mean of 35 d after insertion of the catheter, so adequate anticoagulation should last at least 6 weeks. However, during this period the patient is at risk of bleeding and infection. Nevertheless, in factor V Leiden-positive patients, anti-thrombotic prophylaxis is necessary. Coagulation test-controlled heparin infusion through the catheter or prolonged low-molecular-weight heparin treatment are possible strategies. The catheter should be removed as soon as possible. As a result of the very high risk of thrombosis in factor V Leiden carriers, placebo-controlled prophylactic studies should not be performed. Further studies should focus on different anticoagulant strategies.
In conclusion, more than half of the patients with the factor V Leiden receiving an allogeneic bone marrow transplantation developed subclavian vein thrombosis. We recommend thrombosis prophylaxis and immediate catheter removal after treatment. We advise testing for the factor V Leiden in all patients receiving an allogeneic bone marrow transplantation.