OXVASC Oxford Vascular

OXVASC, Oxford Vascular Study OCSP, Oxford Community Stroke Project Cl, confidence interval. 

The incidence of new cases of first-ever TIA or stroke can only be reliably assessed in prospective population-based studies (Sudlow and Warlow 1996 Feigin et al. 2003 Rothwell et al. 2004) since hospital-based studies are subject to referral bias (Table 1.4). One of the most comprehensive population-based studies of stroke and TIA incidence is the Oxford Vascular Study, OXVASC, which has near-complete case ascertainment of all patients, irrespective of age, in a population of 91 000 defined by registration with nine general practices in Oxfordshire, UK (Coull et al 2004). This is in contrast to previous studies, such as the MONICA project and the Framingham study, which had an age cut-off at 65 or 75 years or relied on voluntary participation. 

Table 8.2. Numbers of patients referred to dedicated TIA clinics" in whom a non-neurovascular diagnosis was eventually made in Oxford Vascular Study (OXVASC 2002-2004) and the Oxford Community Stroke Project (OCSP 1981-1986)...

Fig. 10.1. Numbers of patients referred to the Oxford Vascular Study (OXVASC) between 2002 and 2007 with suspected transient ischemic attack (TIA) or minor stroke showing clinical diagnosis (before imaging) and revised...

Table 10.3. Rates of infarction, primary hemorrhage or hemorrhagic infarction on CT scan among subjects with probable or definite transient ischemic attack or minor stroke in the Oxford Vascular Study (OXVASC)...

Comparable risks of stroke after TIA were measured in population-based studies in Oxfordshire, UK (Lovett et al. 2003 Coull et al. 2004). In a cohort of 249 consecutive patients with a TIA ascertained in the Oxford Vascular Study (OXVASC) over a 30-month period, stroke risks at two and seven days were 6.8% (95% confidence interval [Cl], 3.7-10.0) and 12.0% (95% Cl, 8.0-16.1), respectively (Rothwell et al. 2007). Although this cohort was smaller than the Californian cohort, it had the advantages of being population based and, therefore, included patients who were treated as inpatients, as outpatients and managed solely in primary care diagnoses were made by an experienced stoke physician and follow-up was face to face with independent adjudication of outcome events. 

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