2.5. Data analysis

We evaluated the effects of adding esmolol to the prehospital protocol between December 10, 2018 and June 10, 2020. A historical control period between June 10, 2017 and December 9, 2018 was selected for secondary comparisons of the proportion of patients with prehospital ROSC, 24‐hour survival, and survival to hospital discharge.

Descriptive statistics were calculated with frequencies and percentages for categorical variables and continuous variables summarized using medians and interquartile ranges (IQR). Patient and encounter characteristics were compared between the cohort of patients receiving esmolol and those in the control period using Wilcoxon Rank Sum tests for non‐normally distributed continuous variables and chi‐square tests for categorical variables. Comparisons of the proportion of patients experiencing prehospital ROSC, surviving to 24 hours after hospital arrival, and surviving to hospital discharge between patients receiving esmolol and those in the historical control period were made using chi‐square tests. For all comparative tests, we set an alpha level of 0.05 as the threshold for determining statistical significance. Multivariable logistic regression modeling was used to assess the association between esmolol and outcome variables while controlling for patient age, sex, and initial rhythm. All analyses were completed using Stata IC Version 15.1 (StataCorp LLC, College Station, TX).