Thromboembolic complications remain a major public health burden, making antithrombotic agents one of the most widely prescribed groups of medication, but the treatment is often challenging as it... Show moreThromboembolic complications remain a major public health burden, making antithrombotic agents one of the most widely prescribed groups of medication, but the treatment is often challenging as it at the same time increases risk of bleeding. With nationwide data from Statistics Netherlands, antithrombotic therapy and relevant clinical outcomes were comprehensively examined in the patient population of atrial fibrillation, overall or among those with comorbid cancer. The results suggest the patient population was increasingly receiving anticoagulants, driven by the newly introduced medication- direct oral anticoagulant and guided by the CHA2DS2-VASc score, and meanwhile the patient population experienced fewer ischemic stroke and major bleeding. In spite of these promising changes, suboptimal medication adherence and potential underuse of anticoagulants remain directions for further improvement. Antithrombotic agent use during pregnancy was also examined in the general Dutch pregnant population, which featured a surge in antiplatelet prescriptions, and risk of preeclampsia/eclampsia decreased and several newborn outcomes improved simultaneously. Together, the studies presented in this thesis provide an overview of antithrombotic therapy in the Netherlands in recent years, providing insights for further improving this treatment and relevant patient outcomes. Show less
This thesis addresses potential threats to the validity of observational epidemiological studies. Examples of these potential sources of bias are confounding, missing data, selection bias, and... Show moreThis thesis addresses potential threats to the validity of observational epidemiological studies. Examples of these potential sources of bias are confounding, missing data, selection bias, and measurement error. Although various methods have been developed to mitigate these biases, it is often unclear which methods can be used in which empirical settings. It is also common that issues discussed in methodological studies are overlooked in clinical research. Thus, we investigated problems ofmissing data, selection bias, and measurement error occurring in several specific observational settings and discuss how to optimally handle them. Show less
Breast cancer is a heterogeneous disease with substantial variability in outcome, risk factors and response to treatment. Therefore, a better understanding of the factors influencing breast cancer... Show moreBreast cancer is a heterogeneous disease with substantial variability in outcome, risk factors and response to treatment. Therefore, a better understanding of the factors influencing breast cancer outcome could lead to improved prognostication and better stratification of patients into treatment subgroups. To this end, we investigated the association of hereditary genetic variants and non-genetic breast cancer risk factors with breast cancer outcome, and assessed the evidence of potential differential associations across specific tumor subtypes and patient subgroups defined by clinic-pathological variables related to tumor biology and type of systemic treatment. We focused on two breast cancer outcomes, namely survival and risk of developing a second breast cancer in the contralateral breast (contralateral breast cancer).Based on data from a large international cohort of breast cancer patients, we found clear associations of several known lifestyle breast cancer risk factors with survival in breast cancer patients, independently from specific tumor subtype, and of coding hereditary genetic variants in five known breast cancer susceptibility genes with contralateral breast cancer risk. There was also evidence of association of coding hereditary genetic variants in three known breast cancer genes with breast cancer-specific survival (time to death due to breast cancer), although weaker than for contralateral breast cancer risk. These factors could be incorporated into prediction models for breast cancer outcome thereby potentially improving prognostic estimates and breast cancer counseling. In particular, the findings related to contralateral breast cancer risk are relevant to treatment decisions, follow-up and screening of breast cancer patients. Show less
Stroke is one of the leading causes of disability and death worldwide. Prevention of stroke is therefore essential. Effective prevention should be tailored to the clinical characteristics,... Show moreStroke is one of the leading causes of disability and death worldwide. Prevention of stroke is therefore essential. Effective prevention should be tailored to the clinical characteristics, lifestyle, and environment of the individual, among others. This is also known as precision prevention. An important example illustrating the need for precision prevention is the existence of sex differences in stroke occurrence. In practice, for predicting stroke risk, only traditional risk factors (such as smoking and hypertension) are included, and women-specific risk factors are not yet routinely included. As a result, women with an increased risk of stroke may be missed, which also prevents timely initiation of preventive treatments. In this thesis, I tried to lay the foundation for precision prevention of stroke in women.Part I discussed the pathophysiology underlying women-specific risk factors for stroke, and gender differences in the clinical presentation of stroke. I found that the mechanisms underlying the relationship between women-specific risk factors and stroke, in particular the relationship between migraine and cerebral infarctions, seem to be particularly significant in the childbearing phase of life.In Part II, I described how health data from the EHR can be used to develop prediction models for the risk of myocardial infarction or stroke specifically for women under 50 years of age, and found that women-specific risk factors can add value in the predictions. However, there is still a long way to go to actually implement these models in practice, such as testing them on new datasets, and complying with current laws and regulations for safe application. Show less
Studies in this thesis were performed in a secondary care cohort of patients with hand osteoarthritis. Several factors were investigated for their association with disease status and disease... Show moreStudies in this thesis were performed in a secondary care cohort of patients with hand osteoarthritis. Several factors were investigated for their association with disease status and disease progression after two years. These factors included comorbidity, illness perceptions and MRI-defined inflammatory features such as bone marrow lesions, synovitis and joint effusion. In the MRI studies we found that these MRI-features have a clinically relevant role for their association with pain (at the same moment and after two years) and progression of radiographic damage after two years. In the second part of this thesis we evaluated the clinimetric properties of two new instruments: self-reported painful joint count and semi-automatic joint space width measurements. Show less
The prevalence of musculoskeletal complaints in professional musicians is higher compared to the general population (Odds ratio 2.3): point prevalences in the literature range between 9% and 68%;... Show moreThe prevalence of musculoskeletal complaints in professional musicians is higher compared to the general population (Odds ratio 2.3): point prevalences in the literature range between 9% and 68%; year prevalences range between 41% and 93%. Female gender is the most important risk factor. Also among amateur musicians musculoskeletal complaints are frequent, the year prevalence of playing-related is 68%. Female gender, a sudden increase in playing time and playing a string instrument were the main risk factors. Among professional musicians with musculoskeletal complaints, the impact of these complaints on daily functioning is appreciated as more severe, compared non-musicians with musculoskeletal complaints. Also, healthcare usage is higher among musicians with these complaints. Musicians with complaints report worse illness perceptions compared to non-musicians with musculoskeletal complaints. In the last part of this thesis biomechanical aspects of violin playing are evaluated: Violinists with complaints show more activity of the superficial neck and shoulder muscles while playing the instrument, which is hypothesized to be the result of co-contraction. From a biomechanical point of view, playing without a shoulder rest, or with a shoulder rest with minimal height seems favourable, the latter being subjectively most comfortable by the violinists. Show less
This thesis aimed to identify possible risks associated with erythropoiesis-simulating agent (ESA) use. First, trends in anemia management are described, showing less ESA use in Swedish patients... Show moreThis thesis aimed to identify possible risks associated with erythropoiesis-simulating agent (ESA) use. First, trends in anemia management are described, showing less ESA use in Swedish patients with chronic kidney disease (CKD) and less ESA-treated patients had a hemoglobin above 12 g/dL. Furthermore it is shown that ESA- treated pre-dialysis patients in the Netherlands received more antihypertensive agents than patients without ESA, confirming the hypertensive effect of ESA. However, no relevant difference in routinely measured blood pressure was observed between patients with and without ESA treatment, thus the hypertensive effect of ESAs could be controlled in clinical practice. In addition, no excess of thrombotic events was shown in ESA-treated dialysis patients compared to patients without ESA treatment. In contrast, a higher risk of cardiovascular events with ESA use was indicated in Danish patients with multiple myeloma and myelodyslastic syndrome. Also, with two analytical approaches, a harmful effect of high ESA doses on mortality was indicated in Dutch dialysis patients. Last, it was shown that ESA resistance was associated with mortality in both hemodialysis and peritoneal dialysis patients. To conclude, treatment with high ESA doses was associated with a higher risk of mortality, but the mechanism is largely unknown. Show less
Currently, 35-45% of newly diagnosed breast cancer patients in developed countries is aged 65 years and older. Older women with breast cancer comprise a heterogeneous group due to large differences... Show moreCurrently, 35-45% of newly diagnosed breast cancer patients in developed countries is aged 65 years and older. Older women with breast cancer comprise a heterogeneous group due to large differences with regard to concomitant diseases, physiological reserve and functional status. Current guidelines for breast cancer are based on studies that were mostly performed in younger patients. Therefore, treatment of older women with breast cancer is not evidence-based, and it cannot be expected that clinical trials will fill this gap of knowledge in the near future. The aim of this thesis was to investigate several aspects of breast cancer treatment in older women. In Part I, several aspects of treatment in older breast cancer patients were assessed. Part II assessed methodological aspects of studying breast cancer in older patients. This thesis has shown that older patients are at increased risk for overdiagnosis of breast cancer due to population screening, with potential harmful effects due to the increased risk of complications of treatment. Despite changing treatment strategies, breast cancer prognosis of older women has not improved. Current treatment strategies and decisions tools are insufficient. Observational studies will become increasingly important in this patient population, the use of accurate methods will be essential. Show less
