R package AHR. Methods for estimation of multivariate average hazard ratios as defined by Kalbfleisch and Prentice. The underlying survival functions of the event of interest in each group can be estimated using either the (weighted) Kaplan-Meier estimator or the Aalen-Johansen estimator for the transition probabilities in Markov multi-state models. Right-censored and left-truncated data is supported. Moreover, the difference in restricted mean survival can be estimated.