ID, time, event, group and x1,
where
ID: Subjects identification;
time: Event or censoring time;
event: Event indicator, 1 = event, 0 = censored;
group: Treatment group indicator;
x1: Continuous variable.
Fu, H., Luo, L., & Qu Y. (2014). Hypoglycemic Events Analysis via Recurrent Time-to-Event (HEART) Models. Journal of biopharmaceutical statistics, Epub 2014 Dec 1.