Risk prediction and risk reduction in patients with manifest arterial disease

Abstract

Risicovoorspelling en risicoverlaging bij patienten met manifest vaatlijden Engelstalig abstract The number of patients with clinical manifest arterial disease is increasing because of the aging of the population. Patients with manifest arterial disease have an increased risk of a new vascular event in the same or different arterial bed. Medical treatment of vascular risk factors (hypertension, hyperlipidemia, diabetes mellitus) and lifestyle changes (healthy diets, exercise, quit smoking) can reduce the future risk. Studies presented in this thesis not only confirm the high prevalence of vascular risk factors in patients with manifest arterial disease, but also demonstrate the relevance of non-invasive screening on asymptomatic arterial disease. Standard screening for asymptomatic arterial disease identified a limited number of vascular abnormalities that necessitated immediate medical attention. But the screening revealed a high prevalence of peripheral arterial disease and carotid artery stenosis. Furthermore we found that the presence of asymptomatic carotid artery stenosis was associated with a 50% increased risk of recurrent vascular events (hazard ratio (HR) 1.5, 95% CI 1.1 - 2.1) in patients with clinical manifest arterial disease or type 2 diabetes but without a history of cerebral ischemia. Thus, the presence of asymptomatic carotid artery stenosis of ? 50% indicates higher risk in patients already known to be at high risk. We evaluated new strategies aiming at better risk factor-management in order to delay or to prevent progression of atherosclerosis. An additional letter to the treating specialist with medical treatment recommendations in case of new or poorly controlled risk factors resulted in marginal increase in medication use compared with trends in medication use in usual care. The extra care given by a nurse practitioner in addition to usual care and on top of a vascular screening and prevention program resulted in achievement of more treatment goals for systolic blood pressure (odds ratio (OR) 2.7, 95% CI 1.3 - 5.4), total cholesterol (OR 3.3, 95% CI 1.5 - 7.3), LDL-cholesterol (OR 3.5, 95% CI 1.5 - 8.6), and BMI (OR 4.0, 95% CI 1.2 - 13.1) compared to usual care alone. Another way to achieve effective and efficient risk factor-management may be nurse practitioner guided treatment by Internet-communication with individual patients in addition to usual care. Goal setting to change behavior and the online-relationship between a nurse practitioner and a patient can continue for many years because of the repeated episodic nature of the atherosclerotic vascular disease process. The other part of this thesis concerns about risk prediction. The existing prediction models, intended for patients without cardiovascular disease or diabetes, underestimated the predicted risk in our cohort of patients with clinical manifestations of arterial disease. A new prediction model including traditional risk factors, history and extent of atherosclerosis showed that prediction of recurrent vascular events is possible after 1-year of follow-up but not at 3 or 5-years in patients with symptomatic cardiovascular disease. Indicators for a higher cardiovascular risk in patients with symptomatic peripheral arterial disease are older age (HR 1.85, 95% CI 1.48 - 2.30), impaired renal function (HR 0.79, 95% CI 0.69 - 0.91), elevated homocysteine levels (HR 1.03, 95% CI 1.02 - 1.05), and a history of coronary heart disease (HR 2.30, 95% CI 1.51 - 3.51).