Management of transient ischaemic attack

Stroke is the second biggest killer worldwide accounting for over 10% of global mortality. Previous population based data indicate that Transient Ischaemic Attacks (TIA) may precede stroke in 10 to 25% of cases, providing a critical warning. Without appropriate therapy, the risk of stroke in the first 90 days following TIA ranges from 10% to 17%, half of which occurs in the first 48 hours. Over the past decade, significant attention has been given to optimising TIA care in order to limit subsequent stroke risk. However, there has been a paucity of evidence with regard to the most effective way in which to deliver this care. Prior to the conduct of this thesis, there was uncertainty regarding how best to stratify stroke risk after TIA, and whether such patients could be managed safely without hospital admission. This body of work aimed to evaluate several aspects of TIA management. Specifically, 3 key components were studied: 1) processes for stroke risk stratification following TIA, 2) models of TIA care in tertiary hospitals and 3) the economic implications of TIA hospital care. These evaluations were performed with particular reference to the Monash TIA Triaging Treatment Pathway (M3T), a novel model of TIA care which does not require routine hospital admission. The aim of M3T is to expedite urgent investigations and initiate treatment for TIA patients in the emergency department. Patients are subsequently reviewed in the TIA clinic with urgency of follow-up appointment determined according to the underlying vascular mechanism. The analyses in this thesis were performed in a sample of patients with suspected TIA (n=488) presenting to the emergency department of Monash Medical Centre (a tertiary hospital in Melbourne, Australia) between 2004 and 2007. First, the ABCD2 score, a commonly used risk stratification tool, was evaluated for its ability to predict stroke within 90 days of TIA in the M3T cohort, followed by a meta-analysis of all published data. The results indicated that the score performed poorly in assigning individual risk, with a significant proportion of high risk patients assigned a low risk score. Secondly, the non-admission based M3T model was found to be safe and effective with a 90-day stroke outcome of just 2.36% (95% Confidence Interval 1.15% to 4.8%), similar to the outcomes seen with other international models of rapid TIA care from around the world. Finally, a detailed economic evaluation using microcosting methodology found M3T to be substantially cost-saving with an annual saving of AUD578,069.00 compared with usual routine admission. These are the first analyses to demonstrate the safety, effectiveness and economic merit of a nonadmission based TIA model of care in Australia, which prioritises urgent therapies according to the underlying vascular mechanism. In the current climate of uncertain health funding, these findings suggest that reallocation of hospital resources to clinic based TIA services is a feasible option. If such a model of care is led and carefully supervised by specialist clinicians, it can be beneficial to both patient safety and hospital budgets.Awards: Winner of the School of Clinical Sciences Head of School’s PhD Excellence in 2014