In the Netherlands, no fewer than 360,000 people take anticoagulant medication, for example to reduce the risks of a heart attack or stroke. A quarter of those patients struggle with major swings in their blood values, making the drugs less effective and increasing the chances of serious side effects. UMCG researcher Nic Veeger has discovered that the first thirty days of the treatment can predict whether someone will react well to the drugs. In addition, a minor bleed shortly after the start of the treatment is an indication that a patient will have major problems later. Veeger will be awarded a PhD in Medical Sciences by the University of Groningen on 17 February 2010.
Long-term anticoagulant treatment uses vitamin K antagonists. Vitamin K is one of the main factors responsible for the creation of coagulants in the blood. Drugs that inhibit vitamin K (antagonists) could thus be good anticoagulants. Vitamin K antagonists were registered 60 years ago as anticoagulants. Now over 2% of the Dutch population takes these drugs, and their use is increasing. Ageing and the increase in obesity are playing roles in this.
Veeger’s research has revealed that three-quarters of the patients are helped significantly by vitamin K antagonists such as phenprocoumon and acenocoumarol. Although they have to go to the thrombosis centre for regular checkups (once or twice a month), the degree of coagulation in their blood remains between the target values for 45 to 65% of the time. For a quarter of the patients, the coagulation values are within the target area for no more than 45% of the time. These patients have an increased risk of thromboembolism (a blood clot, which could cause a stroke for example), or a serious bleed.
It is very important to establish quickly whether a patient belongs to the risk group or not. Veeger has discovered two good predictors. First, it has turned out that the first 30 days of the treatment provide a good indication for the course of the rest of the treatment. Second, it turns out that a small, insignificant bleed shortly after starting the treatment is a predictor of more major problems later in the process. Veeger: ‘With the help of these predictors, high-risk patients can be spotted early. It may be possible to achieve better results for this group too with the help of extra measures and perhaps even by adjusting the treatment.’
New anticoagulants are appearing on the international stage, and it is expected that some of them will quickly be allowed on to the Dutch market. Veeger: ‘It’s still early days, but patients who don’t react well to the existing drugs may benefit from these new ones.’ However, it’s not at all clear whether the new drugs will benefit all patients. Veeger: ‘Following your therapy closely is very important when using anticoagulants. We have a very efficient system of specialized Thrombosis Centres in the Netherlands and patient compliance is very high. With the new drugs the patients do not have to be checked by the thrombosis centres any more. Although this is a great advantage, the chances are high that patient compliance will decline. This would negatively affect the efficacy of the new drugs. That’s why we still have to investigate this aspect of the Dutch situation thoroughly.’
Previous research into the effectiveness of anticoagulants usually concentrated on the average risks among large numbers of patients. What is innovative about Veeger’s research is that it charted the risks for individual patients in the long term. Veeger analysed the blood value trends over a long period of time of about six thousand patients.
Nic Veeger (Zwolle, 1961) studied Physiotherapy and Movement Sciences in Groningen and Clinical Epidemiology in Rotterdam. He conducted his PhD research at the Haematology department of the University Medical Center Groningen (UMCG). Veeger’s supervisors were Prof. J.C. Kluin-Nelemans and Prof. J.L. Hillege. He currently works as a clinical epidemiologist at the UMCG Trial Coordination Center. His thesis is entitled ‘Individual Approach Towards Optimal Oral Anticoagulation’.
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