Excess stroke incidence in young Aboriginal people in South Australia: Pooled results from two population-based studies.

Background Retrospective data indicate increased stroke incidence in Aboriginal/Torres Strait Islander (Indigenous) Australians, possibly with poorer outcomes. We present the first prospective population-based stroke incidence study in Indigenous Australians. Methods We pooled data from ASCEND and SEARCH, two prospective "ideal" South Australian stroke incidence studies, ASCEND conducted in urban Northwestern Adelaide (2009-2010) and SEARCH in five South Australian rural centers (2009-2011). We calculated age-standardized incidence for Aboriginal and non-Aboriginal people. Results The study population comprised 261,403 inhabitants. Among 432 first-ever strokes, 13 were in Aboriginal people (median age 51 vs. 78 years for non-Aboriginal people, p < 0.001). Age-standardized stroke incidence per 100,000 in Aboriginal patients (116, 95% CI: 95-137) was nearly two-fold that of non-Aboriginal patients (67, 95% CI: 51-84). Age-stratified excess incidence in Aboriginal people was restricted to those aged < 55 years (incidence rate ratio (IRR) 3.5, 95% CI: 2-7), particularly for intracerebral hemorrhage (IRR: 16, 95% CI: 4-61). Conclusion The excess stroke incidence in Aboriginal South Australians appears substantial, especially in those aged <55 years. Further work is required to delineate and address disparities.

Determining the Number of Ischemic Strokes Potentially Eligible for Endovascular Thrombectomy: A Population-Based Study.

BACKGROUND AND PURPOSE: Endovascular thrombectomy (ET) is standard-of-care for ischemic stroke patients with large vessel occlusion, but estimates of potentially eligible patients from population-based studies have not been published. Such data are urgently needed to rationally plan hyperacute services. Retrospective analysis determined the incidence of ET-eligible ischemic strokes in a comprehensive population-based stroke study (Adelaide, Australia 2009-2010). METHODS: Stroke patients were stratified via a prespecified eligibility algorithm derived from recent ET trials comprising stroke subtype, pathogenesis, severity, premorbid modified Rankin Score, presentation delay, large vessel occlusion, and target mismatch penumbra. Recognizing centers may interpret recent ET trials either loosely or rigidly; 2 eligibility algorithms were applied: restrictive (key criteria modified Rankin Scale score 0-1, presentation delay <3.5 hours, and target mismatch penumbra) and permissive (modified Rankin Scale score 0-3 and presentation delay <5 hours). RESULTS: In a population of 148 027 people, 318 strokes occurred in the 1-year study period (crude attack rate 215 [192-240] per 100 000 person-years). The number of ischemic strokes eligible by restrictive criteria was 17/258 (7%; 95% confidence intervals 4%-10%) and by permissive criteria, an additional 16 were identified, total 33/258 (13%; 95% confidence intervals 9%-18%). Two of 17 patients (and 6/33 permissive patients) had thrombolysis contraindications. Using the restrictive algorithm, there were 11 (95% confidence intervals 4-18) potential ET cases per 100 000 person-years or 22 (95% confidence intervals 13-31) using the permissive algorithm. CONCLUSIONS: In this cohort, ≈7% of ischemic strokes were potentially eligible for ET (13% with permissive criteria). In similar populations, the permissive criteria predict that ≤22 strokes per 100 000 person-years may be eligible for ET.

Adelaide stroke incidence study: declining stroke rates but many preventable cardioembolic strokes.

BACKGROUND AND PURPOSE: Stroke incidence rates are in flux worldwide because of evolving risk factor prevalence, risk factor control, and population aging. Adelaide Stroke Incidence Study was performed to determine the incidence of strokes and stroke subtypes in a relatively elderly population of 148 000 people in the Western suburbs of Adelaide. METHODS: All suspected strokes were identified and assessed in a 12-month period from 2009 to 2010. Standard definitions for stroke and stroke fatality were used. Ischemic stroke pathogenesis was classified by the Trial of ORG 10172 in Acute Stroke Treatment criteria. RESULTS: There were 318 stroke events recorded in 301 individuals; 238 (75%) were first-in-lifetime events. Crude incidence rates for first-ever strokes were 161 per 100 000 per year overall (95% confidence interval [CI], 141-183), 176 for men (95% CI, 147-201), and 146 for women (95% CI, 120-176). Adjusted to the world population rates were 76 overall (95% CI, 59-94), 91 for men (95% CI, 73-112), and 61 for women (95% CI, 47-78). The 28-day case fatality rate for first-ever stroke was 19% (95% CI, 14-24); the majority were ischemic (84% [95% CI, 78-88]). Intracerebral hemorrhage comprised 11% (8-16), subarachnoid hemorrhage 3% (1-6), and 3% (1-6) were undetermined. Of the 258 ischemic strokes, 42% (95% CI, 36-49) were of cardioembolic pathogenesis. Atrial fibrillation accounted for 36% of all ischemic strokes, of which 85% were inadequately anticoagulated. CONCLUSIONS: Stroke incidence in Adelaide has not increased compared with previous Australian studies, despite the aging population. Cardioembolic strokes are becoming a higher proportion of all ischemic strokes.

Ischaemic stroke among young people aged 15 to 50 years in Adelaide, South Australia.

OBJECTIVES: To report risk factors, aetiology and neuroimaging features among a large series of young Australian patients who were admitted to hospital for a first-ever occurrence of ischaemic stroke; to analyse the effect of age, sex and ethnicity on the presence of risk factors; and to compare Australian and overseas data. DESIGN, SETTING AND PATIENTS: Retrospective evaluation of data for all patients aged from 15 to 50 years who were admitted to a public hospital in Adelaide, South Australia, from January 2006 to June 2010 with a primary diagnosis of ischaemic stroke. RESULTS: Among 326 patients (184 males), the most frequent stroke risk factors overall were dyslipidaemia (187), smoking (161), hypertension (105) and obesity (92). Fifty-one patients used illicit drugs, mostly comprising marijuana and amphetamines. The most frequent stroke aetiologies overall were cardioembolism (85), arterial dissection (49), and small-vessel occlusion (31). Cardioembolism was highly prevalent among our study population compared with patients in other countries. Neuroimaging showed that more patients in our study had strokes that involved both vascular territories concurrently (9%) compared with patients in other countries. CONCLUSIONS: Risk factors, aetiology and features of ischaemic stroke among young people in Adelaide differ significantly from published data for young patients around the world. Patients in Adelaide are more likely to be obese, to be misusing marijuana and amphetamines, to suffer a cardioembolic event and to have a stroke that concurrently affects both the anterior and posterior cerebral circulation.

A population-based study of thrombolysis for acute stroke in South Australia.

OBJECTIVE: To report the rate of thrombolysis for treating acute stroke in South Australia from October 2007 to September 2009. We hypothesised that the rate of thrombolytic therapy would be related to distance from an acute stroke unit. DESIGN, SETTING AND PATIENTS: An observational, population-based, retrospective review of case notes and imaging, using multiple case-ascertainment methods. Patients administered a thrombolytic agent by any method for suspected ischaemic stroke in urban, rural, public and private hospitals in SA (covering a population of 1.5 million people) were included. MAIN OUTCOME MEASURES: Absolute and relative contraindications for thrombolysis administration in each case, according to the 2007 National Stroke Foundation guidelines; incidence of haemorrhage; and population thrombolysis rates according to distance from an acute stroke unit. RESULTS: A total of 158 cases of thrombolytic therapy for suspected acute ischaemic stroke were identified in 157 patients. Fifteen patients (10%) had symptomatic intracranial haemorrhage, of whom eight (5%) died within 3 months. Seven patients had symptomatic extracranial haemorrhage. Five patients (3%) received thrombolysis despite absolute contraindications. Patients living closer to stroke units were more likely to receive thrombolysis. CONCLUSIONS: Rates of symptomatic haemorrhage after thrombolysis were similar to those in voluntary registries. A large proportion of South Australians are currently missing out on acute stroke therapy as a result of poor access to acute stroke units in both urban and rural settings. It is estimated that fewer than 2% of ischaemic stroke patients are administered thrombolysis in SA.