Résumé
Logistic regression is a common classification method in supervised learning. Surprisingly, there are very few solutions for performing logistic regression with missing values in the covariates. A complete approach based on a stochastic approximation version of the EM algorithm is proposed in order to perform statistical inference with missing values, including the estimation of the parameters and their variance, derivation of confidence intervals, and also a model selection procedure. The problem of prediction for new observations on a test set with missing covariate data is also tackled. Supported by a simulation study in which the method is compared to previous ones, it has proved to be computationally efficient, and has good coverage and variable selection properties. The approach is then illustrated on a dataset of severely traumatized patients from Paris hospitals by predicting the occurrence of hemorrhagic shock, a leading cause of early preventable death in severe trauma cases. The aim is to improve the current red flag procedure, a binary alert identifying patients with a high risk of severe hemorrhage. The method is implemented in the R package misaem.