Using Machine Learning to Improve the Prediction of Functional Outcome in Ischemic Stroke Patients

Ischemic stroke is a leading cause of disability and death worldwide among adults. The individual prognosis after stroke is extremely dependent on treatment decisions physicians take during the acute phase. In the last five years, several scores such as the ASTRAL, DRAGON, and THRIVE have been proposed as tools to help physicians predict the patient functional outcome after a stroke. These scores are rule-based classifiers that use features available when the patient is admitted to the emergency room. In this paper, we apply machine learning techniques to the problem of predicting the functional outcome of ischemic stroke patients, three months after admission. We show that a pure machine learning approach achieves only a marginally superior Area Under the ROC Curve (AUC) (<inline-formula><tex-math notation="LaTeX">$0.808\pm 0.085$</tex-math><alternatives><inline-graphic xlink:href="monteiro-ieq1-2811471.gif"/></alternatives></inline-formula>) than that of the best score (<inline-formula><tex-math notation="LaTeX">$0.771\pm 0.056$</tex-math><alternatives><inline-graphic xlink:href="monteiro-ieq2-2811471.gif"/></alternatives></inline-formula>) when using the features available at admission. However, we observed that by progressively adding features available at further points in time, we can significantly increase the AUC to a value above 0.90. We conclude that the results obtained validate the use of the scores at the time of admission, but also point to the importance of using more features, which require more advanced methods, when possible.