national cardiac arrest study done in the United Kingdom led to development of a predictive model to predict the survival-to-discharge outcome following IHCA, which included factors such as age, prior length of stay, reason for admission, arrest location, and arrest rhythm.16 One of the predictors was whether the patient deterioration was documented, but this predictor was not entered into the final risk model. In this study, only 5% of the population were reported as deteriorating and the study did not describe how the patient deteriorated. More than half of the patients experienced the cardiac arrest in a ward, making immediate detection and response difficult. As is widely acknowledged, it is difficult in large dataset-based studies to capture detailed information about changes in vital signs, and the strength of our study is that MEWS could describe detailed changes in vital signs.