Plot of the association between the number of previous COVID-19 tracheal intubations before current intubation episode and the likelihood of successfully intubating at first attempt (predicted success computed from the mixed-effects logistic regression model). In this plot, the other model covariates are set to the mean (for numeric variables) or set to their reference level (for categorical variables). The black line indicates the prediction estimate for a given number of previous COVID-19 tracheal intubations adjusted for other covariates, and the gray area indicates the 95% CI of the prediction estimate.