Simulating recurrent events that mimic actual data: a review of the literature with emphasis on event-dependence

We conduct a review to assess how the simulation of repeated or recurrent events are planned. For such multivariate time-to-events, it is well established that the underlying mechanism is likely to be complex and to involve in particular both heterogeneity in the population and event-dependence. In this respect, we particularly focused on these two dimensions of events dynamic when mimicking actual data. Next, we investigate whether the processes generated in the simulation studies have similar properties to those expected in the clinical data of interest. Finally we describe a simulation scheme for generating data according to the timescale of choice (gap time/ calendar) and to whether heterogeneity and/or event-dependence are to be considered. The main finding is that event-dependence is less widely considered in simulation studies than heterogeneity. This is unfortunate since the occurrence of an event may alter the risk of occurrence of new events.