Childhood arterial ischaemic stroke incidence, presenting features, and risk factors: a prospective population-based study

Background 
Arterial ischaemic stroke is an important cause of acquired brain injury in children. Few prospective population-based studies of childhood arterial ischaemic stroke have been undertaken. We aimed to investigate the epidemiology and clinical features of childhood arterial ischaemic stroke in a population-based cohort.

Methods 
Children aged 29 days to less than 16 years with radiologically confirmed arterial ischaemic stroke occurring over a 1-year period (July 1, 2008, to June 30, 2009) residing in southern England (population denominator 5.99 million children) were eligible for inclusion. Cases were identified using several sources (paediatric neurologists and trainees, the British Paediatric Neurology Surveillance Unit, paediatricians, radiologists, physiotherapists, neurosurgeons, parents, and the Paediatric Intensive Care Audit Network). Cases were confirmed by personal examination of cases and case notes. Details of presenting features, risk factors, and investigations for risk factors were recorded by analysis of case notes. Capture recapture analysis was used to estimate completeness of ascertainment.

Findings 
We identified 96 cases of arterial ischaemic stroke. The crude incidence of childhood arterial ischaemic stroke was 1.60 per 100 000 per year (95% CI 1.30-1.96). Capture recapture analysis suggested that case ascertainment was 89% (95% CI 77-97) complete. The incidence of arterial ischaemic stroke was highest in children aged under 1 year (4.14 per 100 000 per year, 95% CI 2.36-6.72). There was no difference in the risk of arterial ischaemic stroke between sexes (crude incidence 1.60 per 100 000 per year [95% CI 1.18-2.12] for boys and 1.61 per 100 000 per year [1.18-2.14] for girls). Asian (relative risk 2.14, 95% CI 1.11-3.85; p=0.017) and black (2.28, 1.00-4.60; p=0.034) children were at higher risk of arterial ischaemic stroke than were white children. 82 (85%) children had focal features (most commonly hemiparesis) at presentation. Seizures were more common in younger children ( 5 years; p <00001). At least one risk factor for childhood arterial ischaemic stroke was identified in 80 (83%) cases.

Interpretation 
Age and racial group, but not sex, affected the risk of arterial ischaemic stroke in children. Investigation of such differences might provide causative insights.