Homocysteine is a risk factor for venous thrombosis. Elevated concentrations can be treated with folic acid, vitamin B6 and vitamin B12. The main study (chapter 9) in this thesis is a randomized... Show moreHomocysteine is a risk factor for venous thrombosis. Elevated concentrations can be treated with folic acid, vitamin B6 and vitamin B12. The main study (chapter 9) in this thesis is a randomized placebo-controlled trial in which patients with a first event of deep-vein thrombosis or pulmonary embolism are treated with above mentioned vitamins or a placebo. There was no effect of vitamin treatment on recurrent thrombosis. A case-control study is described whichs shows that elevated homocysteine concentrations are a risk factor for venous thrombosis and pulmonary embolism in elderly patients (chapter 7). Two studies deal with acidic citrate as an anticoagulant in blood collection tubes. We show that acidic citrate stabilizes homocysteine concentrations at room temperature (chapter 3) and that the homocysteine concentrations measured in blood collection tubes with acidic citrate as anticoagulant correlate well with the concentrations measured in blood tubes with EDTA as anticoagulant (chapter 4). One study compared patients on and off anticoagulant therapy. There was no influence of coumarin derivatives on plasma homocysteine concentrations (chapter 5). The endogeous thrombin potential is not different in patients with high homocysteine concentrations in comparison to patients with low homocysteine concentrations (chapter 6). Show less
The studies described in this thesis had two main aims: 1) To study the quality of life of patients with venous thrombosis and to examine the role of illness perceptions in explaining the quality... Show moreThe studies described in this thesis had two main aims: 1) To study the quality of life of patients with venous thrombosis and to examine the role of illness perceptions in explaining the quality of life of these patients. 2) To assess the psychological consequences of genetic testing for thrombophilia, using the Common-Sense Model (Leventhal et al.., 1984) as a theoretical framework.The studies performed to assess aim 1 form the first part of the thesis and show that the effect of venous thrombosis on quality of life should not be underestimated, even some years after the venous thrombosis. Furthermore, results give an indication that besides the presence of the postthrombotic syndrome, illness perceptions may help to explain quality of life in patients with venous thrombosis.In the second part of the thesis aim 2 is addressed. Genetic testing for thrombophilia does not have many adverse psychological consequences. However, certain vulnerable individuals may still experience considerable worry about getting venous thrombosis. Furthermore, results indicate that the Common-Sense Model can act as a useful framework to enhance understanding of how factors contribute to influence psychological response to risk of disease. Show less
Venous thrombosis is a well-known complication of central vein catheters (CVCs), which may cause serious morbidity and may result in potentially lethal complications such as pulmonary embolism. In... Show moreVenous thrombosis is a well-known complication of central vein catheters (CVCs), which may cause serious morbidity and may result in potentially lethal complications such as pulmonary embolism. In this thesis the general risk of CVC related thrombosis has been assessed, i.e., what is the overall risk of developing CVC related thrombosis? Which patients are prone to develop thrombosis with its associated morbidity? Are we able to predict this risk by routine surveillance in "high-risk" patients? Better knowledge of the incidence of CVC related thrombosis and identification of high-risk groups will assist clinicians in decision making about CVC use in the various patient-groups and in whom anticoagulant prophylaxis may be warranted. In summary, the a priori determination of common inherited and acquired risk factors may form a basis to guide (prophylactic) treatment decisions. Vulnerable patients may benefit the most, i.e. those who have a high risk of clinically manifest thrombosis, and who are at risk of hemorrhage, such as patients who undergo intensive chemotherapy. Besides, surveillance of these patients with screening by ultrasound, or alternatively surveillances cultures, may be useful to identify patients at high or low risk for clinically manifest CVC related thrombosis, and focused early intervention may be initiated. Show less
