Improving secondary prevention after transient ischaemic attack and minor ischaemic stroke

Stroke is the second most common cause of death worldwide and the leading cause of long-term neurological disability. In the UK, stroke accounts for approximately 6% of total National Health Service and Social Services expenditure. The burden of stroke is predicted to increase because of the ageing population. Whilst effective primary prevention is important, about 30% of strokes occur in individuals with a previous transient ischaemic attack (TIA) or minor stroke. Recent prospective studies have shown a high early risk of recurrent stroke in the days after TIA or minor stroke. The prompt use of preventative strategies has been shown to be highly effective in reducing this early risk of recurrence and there is now a consensus in favour of rapid access services and urgent secondary prevention after TIA. However, there are several areas where clinical practice still needs to be improved, including delays in seeking medical attention, the reliability of clinical diagnosis of TIA in the acute phase, prediction of stroke recurrence risk and the control of risk factors, particularly blood pressure (BP), in longer-term secondary prevention. My thesis will focus on these clinically important areas.
I have used data from a population-based study; the Oxford Vascular Study (OXVASC). OXVASC is a prospective, population-based incidence study of vascular disease in all territories in Oxfordshire, UK, which started in 2002 and is ongoing. The study population comprises approximately 91 000 individuals registered with nine general practices and uses multiple overlapping methods of “hot” and “cold” pursuit to identify all patients with acute vascular events.
The research described in this thesis has several clinically useful findings which address areas for improvement during the patient journey after TIA and minor ischaemic stroke. First, I have highlighted that despite public education campaigns, about 70% of patients still fail to correctly recognise TIA or minor stroke symptoms and about 30% delay seeking medical attention for over 24 hours. Second, I have shown that recurrent TIA within 7-days is not associated with a greater stroke risk than after a single TIA, other than in the capsular warning syndrome. Third, in patients with definite posterior circulation TIA or stroke, preceding transient isolated “brainstem” symptoms occur in 26%, which has implications for the current diagnostic criteria for TIA. Fourth, I have shown that the Face Arm and Speech Test does not reliably identify patients at high early risk of recurrent stroke after TIA and minor stroke and has limited potential to improve access to care. Fifth, I have shown that outpatient management of clinic-referred minor stroke is feasible and may be as safe as inpatient care. Sixth, that stroke recurrence risk after minor stroke is delayed compared with TIA, and is high during the subacute phase despite current best medical treatment. Seventh, I have assessed Bluetooth- based home BP monitoring after TIA or minor stroke as a way of achieving better BP control and shown that this method is feasible, irrespective of age, and patient satisfaction is high. Finally, I have studied the late outcomes after TIA and stroke in OXVASC in comparison with a similar cohort from the 1980’s. I have shown that the age and sex specific later risk of recurrent stroke after TIA and stroke in Oxfordshire has fallen. However, the risk of fatal recurrent stroke remains high in contrast with the risk of fatal cardiac events which is low.

Keywords: transient ischaemic attack
Stroke prevention
epidemiology
Advisor: Rothwell, P