ArticlesPopulation-based study of event-rate, incidence, case fatality, and mortality for all acute vascular events in all arterial territories (Oxford Vascular Study)
Introduction
Arterial disease, due usually to atherosclerosis, is the most prevalent chronic disease in the developed world,1, 2 and is rapidly increasing in importance in the developing world.3, 4 Although atherosclerotic arterial disease can cause stable or slowly progressive clinical syndromes, such as stable angina and intermittent claudication, the main clinical burden consists of acute, usually ischaemic, vascular events. Acute arterial vascular events are the leading cause of premature death and disability in the developed world.1, 2 However, although acute coronary, cerebrovascular, and peripheral vascular events share the same underlying pathologies, risk factors, and preventive treatments, they are rarely studied concurrently. No large, prospective population-based study of the incidence and outcome of all acute symptomatic vascular events in all arterial territories and all age groups in the same population at the same time has been undertaken. Routinely collected mortality data are of limited value and can be biased,5, 6 and previous epidemiological studies, such as the WHO MONICA Project,7, 8 have included only certain types of events and have usually been limited to individuals younger than 65 years.
Therefore, we have virtually no reliable information about the comparative epidemiology or the relative clinical burdens of different acute vascular syndromes in the same population. Previous data would be of only limited value, in view of the changes in mortality and case fatality due to stroke and acute coronary events that have occurred in recent decades,9, 10, 11, 12 and the probable effect of the ageing population. Moreover, changes in the diagnostic criteria for acute coronary syndromes13, 14, 15 will have substantially altered estimates of incidence, event rates, and case fatality. To measure the current burden of all acute cardiovascular events and comparative epidemiology of events in different arterial territories, we prospectively studied event rates, incidence, 30-day case-fatality rates, and mortality rates of all acute symptomatic arterial vascular events presenting to medical attention in a subpopulation of Oxfordshire, UK, in 2002–05 (Oxford Vascular Study [OXVASC]). We report these rates by age, sex, and arterial territory.
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Patients
The OXVASC study population consisted of all 91 106 individuals, irrespective of age, registered with 63 family physicians in nine general medical practices in Oxfordshire, UK. In the UK, general practices provide primary health care for registered individuals and hold a lifelong record of all medical consultations (from the National Health Service [NHS] and private health care), and details of treatments, blood pressure, and investigations. In Oxfordshire, an estimated 97% of the true
Results
The age and sex structure of our study population (table 1), which was the mean of the three mid-year-population age and sex structures of our study practices, closely resembles that of the entire UK population. 2024 acute vascular events in 1657 individuals were ascertained during the study, of which 1793 (89%) were definite events, 169 (8%) were probable events, and 62 (3%) were unclassifiable deaths. With the exclusion of out-of-hospital deaths, the first method of ascertainment was by hot
Discussion
OXVASC is a comprehensive population-based study of the acute manifestations of vascular disease in all arterial territories without exclusions by age, which has enabled us to document the high rates of acute vascular events that occur outside the coronary arterial territory and the steep rise in event rates with age in all territories. In particular, we have shown that acute cerebrovascular events are at least as frequent as acute coronary events, and that the widespread assumption that
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