Background: The impact of sudden catastrophic events such as terror attacks on stroke is unclear. We investigated the association between the 2019 March 15 Christchurch terror attack and ischaemic stroke admissions and reperfusion therapies.

Methods: We used a Bayesian Poisson model to estimate the effect of the terror attack on ischaemic stroke admissions, the numbers of intracranial large vessel occlusion (LVO) and reperfusion therapy, in the week after the attack compared with weekly data from 1st January 2018 until 21st April 2019. These analyses were repeated for the rest of New Zealand with Christchurch data omitted. The probability of the rate observed in the week following the terror attack being higher than the background rate was calculated for each measure, with a probability higher than 99.5% providing strong evidence of an effect.

Results: In the week starting on Monday, three days after the terror attack, there was an increase in the number of patients with intracranial LVOs (10, background mean rate=2.4, probability P>99.9%) and those receiving reperfusion therapy (9, mean rate=2.6, P=99.9%), compared with the baseline rates. There was no difference in the total number of ischemic stroke admissions (26, mean rate=27). There was no strong evidence of a change in the numbers of reperfusion therapies or ischaemic stroke admissions in the rest of New Zealand.

Conclusion: Sudden catastrophic events such as terror attacks may increase the numbers of patients developing intracranial LVO requiring stroke reperfusion therapies within the affected community.