AI in stroke: tool outperforms human emergency call handlers in identifying stroke

AI in stroke: A team of researchers from Denmark have developed a new artificial intelligence (AI) framework to address the number of strokes that go unrecognised by human emergency call handlers.[i] The framework outperformed emergency call handlers in recognising stroke for both sexes and across all age groups studied, indicating its potential as a supplementary tool for early and precise stroke identification in the future.

The retrospective study, presented on 18th May at the European Stroke Organisation Conference (ESOC) 2023, drew from the Danish Stroke Registry and a dataset of over 1.5 million calls made to the Copenhagen Emergency Medical Services between 2015 and 2020, which included over 7000 stroke-related calls. Researchers utilised this data to train an AI framework to firstly transcribe the call audio and then predict the risk of stroke based on the transcribed text.

The results, which were evaluated on calls from 2021, revealed that the AI framework performed more effectively than emergency call handlers in identifying stroke cases. The AI framework achieved a recall (sensitivity) of 63.0% and a precision (positive predictive value) of 24.9%, which resulted in an F1 score of 35.7.* In contrast, emergency call handlers had a recall of 52.7% and precision of 17.1%, resulting in an F1 score of 25.8.

Dr Jonathan Wenstrup, one of the lead authors of the study from Copenhagen University Hospital, commented, “As one of the first points of contact for patients seeking medical assistance, emergency call handlers play a critical role in facilitating early and accurate stroke recognition. Many stroke cases can go undetected at this stage, leading to delays in treatment that can have potentially life-threatening consequences for patients.” 

Across Europe, stroke is the second leading cause of death and a major cause of adult disability, affecting over 1 million people each year.[ii],[iii] As populations continue to grow and age, the number of people living with stroke is projected to increase by 27% between 2017 and 2047 in the European Union (EU).iii Despite this, many strokes can be prevented, and if treated early, the likelihood of a positive outcome can be greatly improved.[iv],[v]

“As with any new tool, further research and development are necessary to improve the framework’s accuracy and expand its capabilities. In the future, it may be possible to train the framework directly from the call audio, bypassing the transcription step, as well as incorporating non-word audio – such as a slurred voice – into the training data. However, given the promising results of this study, it is already clear that technologies like this have the capability to completely transform stroke diagnosis and care.”

With the implementation of this new, cost-effective supporting tool, we can enhance stroke identification by call handlers and ensure more patients receive appropriate and timely care, ultimately improving patient outcomes

Dr Jonathan Wenstrup

*Key terms defined

  1. Recall (sensitivity): A measure of the proportion of actual positive cases that are correctly identified
  2. Precision (positive predictive value): A measure of the proportion of predicted positive cases that are actually positive
  3. F1: A harmonic mean of precision and recall, which combines both metrics into a single score


[i] Havtorn, J.D., Wenstrup J., Borgholt L., et al. A retrospective study on deep learning-enabled stroke recognition for a medical help line. Presented at the European Stroke Organisation Conference; 24 May 2023; Munich, Germany.

[ii] OECDiLibrary. Mortality following stroke. Available at:,diseases%E2%80%9D%20in%20Chapter%203) (Accessed: May 2023).

[iii] Wafa HA, et al. Burden of stroke in Europe: Thirty-year projections of incidence, prevalence, deaths, and disability-adjusted life years. Stroke. 2020;51(8):2418–2427.

[iv] American Stroke Association. Preventing Another Stroke. Available at: (Accessed: May 2023).

[v] American Stroke Association. Why Getting Quick Stroke Treatment is Important. Available at: (Accessed: May 2023).